[RFC PATCH v6 10/11] media: imx-asrc: Add memory to memory driver

[Hans Verkuil]

On 13/10/2023 10:31, Shengjiu Wang wrote:
> Implement the ASRC memory to memory function using
> the v4l2 framework, user can use this function with
> v4l2 ioctl interface.
> 
> User send the output and capture buffer to driver and
> driver store the converted data to the capture buffer.
> 
> This feature can be shared by ASRC and EASRC drivers
> 
> Signed-off-by: Shengjiu Wang <shengjiu.wang at nxp.com>
> ---
>  drivers/media/platform/nxp/Kconfig    |   12 +
>  drivers/media/platform/nxp/Makefile   |    1 +
>  drivers/media/platform/nxp/imx-asrc.c | 1248 +++++++++++++++++++++++++
>  3 files changed, 1261 insertions(+)
>  create mode 100644 drivers/media/platform/nxp/imx-asrc.c
> 
> diff --git a/drivers/media/platform/nxp/Kconfig b/drivers/media/platform/nxp/Kconfig
> index 40e3436669e2..8234644ee341 100644
> --- a/drivers/media/platform/nxp/Kconfig
> +++ b/drivers/media/platform/nxp/Kconfig
> @@ -67,3 +67,15 @@ config VIDEO_MX2_EMMAPRP
>  
>  source "drivers/media/platform/nxp/dw100/Kconfig"
>  source "drivers/media/platform/nxp/imx-jpeg/Kconfig"
> +
> +config VIDEO_IMX_ASRC
> +	tristate "NXP i.MX ASRC M2M support"
> +	depends on V4L_MEM2MEM_DRIVERS
> +	depends on MEDIA_SUPPORT
> +	select VIDEOBUF2_DMA_CONTIG
> +	select V4L2_MEM2MEM_DEV
> +	help
> +	    Say Y if you want to add ASRC M2M support for NXP CPUs.
> +	    It is a complement for ASRC M2P and ASRC P2M features.
> +	    This option is only useful for out-of-tree drivers since
> +	    in-tree drivers select it automatically.
> diff --git a/drivers/media/platform/nxp/Makefile b/drivers/media/platform/nxp/Makefile
> index 4d90eb713652..1325675e34f5 100644
> --- a/drivers/media/platform/nxp/Makefile
> +++ b/drivers/media/platform/nxp/Makefile
> @@ -9,3 +9,4 @@ obj-$(CONFIG_VIDEO_IMX8MQ_MIPI_CSI2) += imx8mq-mipi-csi2.o
>  obj-$(CONFIG_VIDEO_IMX_MIPI_CSIS) += imx-mipi-csis.o
>  obj-$(CONFIG_VIDEO_IMX_PXP) += imx-pxp.o
>  obj-$(CONFIG_VIDEO_MX2_EMMAPRP) += mx2_emmaprp.o
> +obj-$(CONFIG_VIDEO_IMX_ASRC) += imx-asrc.o
> diff --git a/drivers/media/platform/nxp/imx-asrc.c b/drivers/media/platform/nxp/imx-asrc.c
> new file mode 100644
> index 000000000000..373ca2b5ec90
> --- /dev/null
> +++ b/drivers/media/platform/nxp/imx-asrc.c
> @@ -0,0 +1,1248 @@
> +// SPDX-License-Identifier: GPL-2.0
> +//
> +// Copyright (C) 2014-2016 Freescale Semiconductor, Inc.
> +// Copyright (C) 2019-2023 NXP
> +//
> +// Freescale ASRC Memory to Memory (M2M) driver
> +
> +#include <linux/dma/imx-dma.h>
> +#include <linux/pm_runtime.h>
> +#include <media/v4l2-ctrls.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-event.h>
> +#include <media/v4l2-fh.h>
> +#include <media/v4l2-ioctl.h>
> +#include <media/v4l2-mem2mem.h>
> +#include <media/videobuf2-dma-contig.h>
> +#include <sound/dmaengine_pcm.h>
> +#include <sound/fsl_asrc_common.h>
> +
> +#define V4L_CAP OUT
> +#define V4L_OUT IN
> +
> +#define ASRC_xPUT_DMA_CALLBACK(dir) \
> +	(((dir) == V4L_OUT) ? asrc_input_dma_callback \
> +	: asrc_output_dma_callback)
> +
> +#define DIR_STR(dir) (dir) == V4L_OUT ? "out" : "cap"
> +
> +#define ASRC_M2M_BUFFER_SIZE (512 * 1024)
> +#define ASRC_M2M_PERIOD_SIZE (48 * 1024)
> +#define ASRC_M2M_SG_NUM (20)

Where do all these values come from? How do they relate?
Some comments would be welcome.

Esp. ASRC_M2M_SG_NUM is a bit odd.

> +
> +struct asrc_fmt {
> +	u32	fourcc;
> +	snd_pcm_format_t     format;

Do you need this field? If not, then you can drop the whole
struct and just use u32 fourcc in the formats[] array.

> +};
> +
> +struct asrc_pair_m2m {
> +	struct fsl_asrc_pair *pair;
> +	struct asrc_m2m *m2m;
> +	struct v4l2_fh fh;
> +	struct v4l2_ctrl_handler ctrl_handler;
> +	int channels[2];
> +	struct v4l2_ctrl_fixed_point src_rate;
> +	struct v4l2_ctrl_fixed_point dst_rate;
> +
> +};
> +
> +struct asrc_m2m {
> +	struct fsl_asrc_m2m_pdata pdata;
> +	struct v4l2_device v4l2_dev;
> +	struct v4l2_m2m_dev *m2m_dev;
> +	struct video_device *dec_vdev;
> +	struct mutex mlock; /* v4l2 ioctls serialization */
> +	struct platform_device *pdev;
> +};
> +
> +static struct asrc_fmt formats[] = {
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_S8,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_S16_LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_U16_LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_S24_LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_S24_3LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_U24_LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_U24_3LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_S32_LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_U32_LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_S20_3LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_U20_3LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_FLOAT_LE,
> +	},
> +	{
> +		.fourcc = V4L2_AUDIO_FMT_IEC958_SUBFRAME_LE,
> +	},
> +};
> +
> +#define NUM_FORMATS ARRAY_SIZE(formats)
> +
> +static snd_pcm_format_t convert_fourcc(u32 fourcc) {
> +
> +	return (__force snd_pcm_format_t)v4l2_fourcc_to_audfmt(fourcc);

Is this cast something that should be done in the v4l2_fourcc_to_audfmt
define instead?

> +}
> +
> +static u32 find_fourcc(snd_pcm_format_t format)
> +{
> +	struct asrc_fmt *fmt;
> +	unsigned int k;
> +
> +	for (k = 0; k < NUM_FORMATS; k++) {
> +		fmt = &formats[k];
> +		fmt->format = convert_fourcc(fmt->fourcc);
> +		if (fmt->format == format)
> +			break;
> +	}
> +
> +	if (k == NUM_FORMATS)
> +		return 0;
> +
> +	return formats[k].fourcc;
> +}
> +
> +static snd_pcm_format_t find_format(u32 fourcc)
> +{
> +	struct asrc_fmt *fmt;
> +	unsigned int k;
> +
> +	for (k = 0; k < NUM_FORMATS; k++) {
> +		fmt = &formats[k];
> +		if (fmt->fourcc == fourcc)
> +			break;
> +	}
> +
> +	if (k == NUM_FORMATS)
> +		return 0;
> +
> +	formats[k].format = convert_fourcc(formats[k].fourcc);
> +
> +	return formats[k].format;

I don't really thing the format field makes any sense. You just
keep setting it.

> +}
> +
> +static int asrc_check_format(struct asrc_pair_m2m *pair_m2m, u8 dir, u32 format)
> +{
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct fsl_asrc_m2m_pdata *pdata = &m2m->pdata;
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	u64 format_bit = 0;
> +	int i;
> +
> +	for (i = 0; i < NUM_FORMATS; ++i) {
> +		if (formats[i].fourcc == format) {
> +			formats[i].format = convert_fourcc(formats[i].fourcc);
> +			format_bit = pcm_format_to_bits(formats[i].format);
> +			break;
> +		}
> +	}
> +
> +	if (dir == IN && !(format_bit & pdata->fmt_in))
> +		return find_fourcc(pair->sample_format[V4L_OUT]);
> +	else if (dir == OUT && !(format_bit & pdata->fmt_out))
> +		return find_fourcc(pair->sample_format[V4L_CAP]);
> +	else
> +		return format;
> +}
> +
> +static int asrc_check_channel(struct asrc_pair_m2m *pair_m2m, u8 dir, u32 channels)
> +{
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct fsl_asrc_m2m_pdata *pdata = &m2m->pdata;
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +
> +	if (channels < pdata->chan_min || channels > pdata->chan_max)
> +		return pair->channels;
> +	else
> +		return channels;
> +}
> +
> +static int asrc_check_rate(struct asrc_pair_m2m *pair_m2m, u8 dir, u32 rate)
> +{
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct fsl_asrc_m2m_pdata *pdata = &m2m->pdata;
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +
> +	if (rate < pdata->rate_min || rate > pdata->rate_max)
> +		return pair->rate[dir];
> +	else
> +		return rate;
> +}
> +
> +static inline struct asrc_pair_m2m *asrc_m2m_fh_to_ctx(struct v4l2_fh *fh)
> +{
> +	return container_of(fh, struct asrc_pair_m2m, fh);
> +}
> +
> +/**
> + * asrc_read_last_fifo: read all the remaining data from FIFO
> + *	@pair: Structure pointer of fsl_asrc_pair
> + *	@dma_vaddr: virtual address of capture buffer
> + *	@length: payload length of capture buffer
> + */
> +static void asrc_read_last_fifo(struct fsl_asrc_pair *pair, void *dma_vaddr, u32 *length)
> +{
> +	struct fsl_asrc *asrc = pair->asrc;
> +	enum asrc_pair_index index = pair->index;
> +	u32 i, reg, size, t_size = 0, width;
> +	u32 *reg32 = NULL;
> +	u16 *reg16 = NULL;
> +	u8  *reg24 = NULL;
> +
> +	width = snd_pcm_format_physical_width(pair->sample_format[V4L_CAP]);
> +	if (width == 32)
> +		reg32 = dma_vaddr + *length;
> +	else if (width == 16)
> +		reg16 = dma_vaddr + *length;
> +	else
> +		reg24 = dma_vaddr + *length;
> +retry:
> +	size = asrc->get_output_fifo_size(pair);
> +	if (size + *length > ASRC_M2M_BUFFER_SIZE)
> +		goto end;
> +
> +	for (i = 0; i < size * pair->channels; i++) {
> +		regmap_read(asrc->regmap, asrc->get_fifo_addr(OUT, index), &reg);
> +		if (reg32) {
> +			*(reg32) = reg;
> +			reg32++;
> +		} else if (reg16) {
> +			*(reg16) = (u16)reg;
> +			reg16++;
> +		} else {
> +			*reg24++ = (u8)reg;
> +			*reg24++ = (u8)(reg >> 8);
> +			*reg24++ = (u8)(reg >> 16);
> +		}
> +	}
> +	t_size += size;
> +
> +	/* In case there is data left in FIFO */
> +	if (size)
> +		goto retry;
> +end:
> +	/* Update payload length */
> +	if (reg32)
> +		*length += t_size * pair->channels * 4;
> +	else if (reg16)
> +		*length += t_size * pair->channels * 2;
> +	else
> +		*length += t_size * pair->channels * 3;
> +}
> +
> +static int asrc_m2m_start_streaming(struct vb2_queue *q, unsigned int count)
> +{
> +	struct asrc_pair_m2m *pair_m2m = vb2_get_drv_priv(q);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct fsl_asrc *asrc = pair->asrc;
> +	struct device *dev = &m2m->pdev->dev;
> +	struct vb2_v4l2_buffer *buf;
> +	bool request_flag = false;
> +	int ret;
> +
> +	dev_dbg(dev, "Start streaming pair=%p, %d\n", pair, q->type);
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to power up asrc\n");
> +		goto err_pm_runtime;
> +	}
> +
> +	/* Request asrc pair/context */
> +	if (!pair->req_pair) {
> +		/* flag for error handler of this function */
> +		request_flag = true;
> +
> +		ret = asrc->request_pair(pair->channels, pair);
> +		if (ret) {
> +			dev_err(dev, "failed to request pair: %d\n", ret);
> +			goto err_request_pair;
> +		}
> +
> +		ret = asrc->m2m_prepare(pair);
> +		if (ret) {
> +			dev_err(dev, "failed to start pair part one: %d\n", ret);
> +			goto err_start_part_one;
> +		}
> +
> +		pair->req_pair = true;
> +	}
> +
> +	/* Request dma channels */
> +	if (V4L2_TYPE_IS_OUTPUT(q->type)) {
> +		pair->dma_chan[V4L_OUT] = asrc->get_dma_channel(pair, IN);
> +		if (!pair->dma_chan[V4L_OUT]) {
> +			dev_err(dev, "[ctx%d] failed to get input DMA channel\n", pair->index);
> +			ret = -EBUSY;
> +			goto err_dma_channel;
> +		}
> +	} else {
> +		pair->dma_chan[V4L_CAP] = asrc->get_dma_channel(pair, OUT);
> +		if (!pair->dma_chan[V4L_CAP]) {
> +			dev_err(dev, "[ctx%d] failed to get output DMA channel\n", pair->index);
> +			ret = -EBUSY;
> +			goto err_dma_channel;
> +		}
> +	}
> +
> +	v4l2_m2m_update_start_streaming_state(pair_m2m->fh.m2m_ctx, q);
> +
> +	return 0;
> +
> +err_dma_channel:
> +	if (request_flag && asrc->m2m_unprepare)
> +		asrc->m2m_unprepare(pair);
> +err_start_part_one:
> +	if (request_flag)
> +		asrc->release_pair(pair);
> +err_request_pair:
> +	pm_runtime_put_sync(dev);
> +err_pm_runtime:
> +	/* Release buffers */
> +	if (V4L2_TYPE_IS_OUTPUT(q->type)) {
> +		while ((buf = v4l2_m2m_src_buf_remove(pair_m2m->fh.m2m_ctx)))
> +			v4l2_m2m_buf_done(buf, VB2_BUF_STATE_QUEUED);
> +	} else {
> +		while ((buf = v4l2_m2m_dst_buf_remove(pair_m2m->fh.m2m_ctx)))
> +			v4l2_m2m_buf_done(buf, VB2_BUF_STATE_QUEUED);
> +	}
> +	return ret;
> +}
> +
> +static void asrc_m2m_stop_streaming(struct vb2_queue *q)
> +{
> +	struct asrc_pair_m2m *pair_m2m = vb2_get_drv_priv(q);
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	struct fsl_asrc *asrc = pair->asrc;
> +	struct device *dev = &m2m->pdev->dev;
> +
> +	dev_dbg(dev, "Stop streaming pair=%p, %d\n", pair, q->type);
> +
> +	v4l2_m2m_update_stop_streaming_state(pair_m2m->fh.m2m_ctx, q);
> +
> +	/* Stop & release pair/context */
> +	if (asrc->m2m_stop)
> +		asrc->m2m_stop(pair);
> +
> +	if (pair->req_pair) {
> +		if (asrc->m2m_unprepare)
> +			asrc->m2m_unprepare(pair);
> +		asrc->release_pair(pair);
> +		pair->req_pair = false;
> +	}
> +
> +	/* Release dma channel */
> +	if (V4L2_TYPE_IS_OUTPUT(q->type)) {
> +		if (pair->dma_chan[V4L_OUT])
> +			dma_release_channel(pair->dma_chan[V4L_OUT]);
> +	} else {
> +		if (pair->dma_chan[V4L_CAP])
> +			dma_release_channel(pair->dma_chan[V4L_CAP]);
> +	}
> +
> +	pm_runtime_put_sync(dev);
> +}
> +
> +static int asrc_m2m_queue_setup(struct vb2_queue *q,
> +				unsigned int *num_buffers, unsigned int *num_planes,
> +				unsigned int sizes[], struct device *alloc_devs[])
> +{
> +	struct asrc_pair_m2m *pair_m2m = vb2_get_drv_priv(q);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +
> +	/* single buffer */
> +	*num_planes = 1;

This isn't quite right. This driver supports VIDIOC_CREATE_BUFS, which userspace
can use to add new buffers on the fly. Note that there is no corresponding DELETE_BUFS
ioctl to delete buffers, but work is in progress for that.

If a driver supports CREATE_BUFS, then queue_setup has to check whether the
values passed by VIDIOC_CREATE_BUFS are valid.

That's done through:

	u32 size;

	if (V4L2_TYPE_IS_OUTPUT(q->type))
		size = pair->buf_len[V4L_OUT];
	else
		size = pair->buf_len[V4L_CAP];

	if (*nplanes)
		return sizes[0] < size ? -EINVAL : 0;

	*num_planes = 1;
	sizes[0] = size;
	return 0;

One of these days this rather ugly construction should be cleaned up.

Oh well...

Regards,

	Hans

> +
> +	/*
> +	 * The capture buffer size depends on output buffer size
> +	 * and the convert ratio.
> +	 *
> +	 * Here just use a fix length for capture and output buffer.
> +	 * User need to care about it.
> +	 */
> +
> +	if (V4L2_TYPE_IS_OUTPUT(q->type))
> +		sizes[0] = pair->buf_len[V4L_OUT];
> +	else
> +		sizes[0] = pair->buf_len[V4L_CAP];
> +
> +	return 0;
> +}
> +
> +static void asrc_m2m_buf_queue(struct vb2_buffer *vb)
> +{
> +	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
> +	struct asrc_pair_m2m *pair_m2m = vb2_get_drv_priv(vb->vb2_queue);
> +
> +	/* queue buffer */
> +	v4l2_m2m_buf_queue(pair_m2m->fh.m2m_ctx, vbuf);
> +}
> +
> +static const struct vb2_ops asrc_m2m_qops = {
> +	.wait_prepare		= vb2_ops_wait_prepare,
> +	.wait_finish		= vb2_ops_wait_finish,
> +	.start_streaming	= asrc_m2m_start_streaming,
> +	.stop_streaming		= asrc_m2m_stop_streaming,
> +	.queue_setup		= asrc_m2m_queue_setup,
> +	.buf_queue		= asrc_m2m_buf_queue,
> +};
> +
> +/* Init video buffer queue for src and dst. */
> +static int asrc_m2m_queue_init(void *priv, struct vb2_queue *src_vq,
> +			       struct vb2_queue *dst_vq)
> +{
> +	struct asrc_pair_m2m *pair_m2m = priv;
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	int ret;
> +
> +	src_vq->type = V4L2_BUF_TYPE_AUDIO_OUTPUT;
> +	src_vq->io_modes = VB2_MMAP | VB2_DMABUF;
> +	src_vq->drv_priv = pair_m2m;
> +	src_vq->buf_struct_size = sizeof(struct v4l2_m2m_buffer);
> +	src_vq->ops = &asrc_m2m_qops;
> +	src_vq->mem_ops = &vb2_dma_contig_memops;
> +	src_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
> +	src_vq->lock = &m2m->mlock;
> +	src_vq->dev = &m2m->pdev->dev;
> +	src_vq->min_buffers_needed = 1;
> +
> +	ret = vb2_queue_init(src_vq);
> +	if (ret)
> +		return ret;
> +
> +	dst_vq->type = V4L2_BUF_TYPE_AUDIO_CAPTURE;
> +	dst_vq->io_modes = VB2_MMAP | VB2_DMABUF;
> +	dst_vq->drv_priv = pair_m2m;
> +	dst_vq->buf_struct_size = sizeof(struct v4l2_m2m_buffer);
> +	dst_vq->ops = &asrc_m2m_qops;
> +	dst_vq->mem_ops = &vb2_dma_contig_memops;
> +	dst_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
> +	dst_vq->lock = &m2m->mlock;
> +	dst_vq->dev = &m2m->pdev->dev;
> +	dst_vq->min_buffers_needed = 1;
> +
> +	ret = vb2_queue_init(dst_vq);
> +	return ret;
> +}
> +
> +static int asrc_m2m_op_s_ctrl(struct v4l2_ctrl *ctrl)
> +{
> +	struct asrc_pair_m2m *pair_m2m =
> +		container_of(ctrl->handler, struct asrc_pair_m2m, ctrl_handler);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	struct fsl_asrc *asrc = pair->asrc;
> +	int src_rate_int, src_rate_frac;
> +	int dst_rate_int, dst_rate_frac;
> +	int new_rate, new_frac;
> +	u64 src_rate, dst_rate;
> +	u64 ratio_pre, ratio_cur;
> +	s64 ratio_diff;
> +	int ret = 0;
> +
> +	switch (ctrl->id) {
> +	case V4L2_CID_ASRC_SOURCE_RATE:
> +		new_rate = ctrl->p_new.p_fixed_point->integer;
> +		new_frac = ctrl->p_new.p_fixed_point->fractional;
> +		src_rate_int = asrc_check_rate(pair_m2m, IN, new_rate);
> +		if (src_rate_int != new_rate ||
> +		    (pair_m2m->src_rate.integer > 0 &&
> +		     src_rate_int != pair_m2m->src_rate.integer))
> +			return -EINVAL;
> +
> +		pair->rate[V4L_OUT] = src_rate_int;
> +
> +		if (new_frac != pair_m2m->src_rate.fractional &&
> +		    new_rate == pair_m2m->src_rate.integer &&
> +		    pair_m2m->dst_rate.integer > 0) {
> +			/*
> +			 * use maximum rate 768kHz as limitation, then we can shift right 21 bit for
> +			 * division
> +			 */
> +			src_rate_frac = pair_m2m->src_rate.fractional;
> +			src_rate = ((s64)src_rate_int << 31) + src_rate_frac;
> +			dst_rate_int = pair_m2m->dst_rate.integer;
> +			dst_rate_frac = pair_m2m->dst_rate.fractional;
> +			dst_rate = (((s64)dst_rate_int << 31) + dst_rate_frac) >> 20;
> +			do_div(src_rate, dst_rate);
> +			ratio_pre = src_rate;
> +
> +			src_rate_frac = new_frac;
> +			src_rate = ((s64)src_rate_int << 31) + src_rate_frac;
> +			dst_rate = (((s64)dst_rate_int << 31) + dst_rate_frac) >> 20;
> +			do_div(src_rate, dst_rate);
> +			ratio_cur = src_rate;
> +
> +			ratio_diff = ratio_cur - ratio_pre;
> +			asrc->m2m_set_ratio_mod(pair, ratio_diff << 11);
> +		}
> +
> +		pair_m2m->src_rate.integer = new_rate;
> +		pair_m2m->src_rate.fractional = new_frac;
> +
> +		break;
> +	case V4L2_CID_ASRC_DEST_RATE:
> +		new_rate = ctrl->p_new.p_fixed_point->integer;
> +		new_frac = ctrl->p_new.p_fixed_point->fractional;
> +
> +		dst_rate_int = asrc_check_rate(pair_m2m, OUT, new_rate);
> +		if (dst_rate_int != new_rate ||
> +		    (pair_m2m->dst_rate.integer > 0 &&
> +		     dst_rate_int != pair_m2m->dst_rate.integer))
> +			return -EINVAL;
> +
> +		pair->rate[V4L_CAP] = dst_rate_int;
> +
> +		if (new_frac != pair_m2m->dst_rate.fractional &&
> +		    new_rate == pair_m2m->dst_rate.integer &&
> +		    pair_m2m->src_rate.integer > 0) {
> +			/*
> +			 * use maximum rate 768kHz as limitation, then we can shift right 21 bit for
> +			 * division
> +			 */
> +			src_rate_int = pair_m2m->src_rate.integer;
> +			src_rate_frac = pair_m2m->src_rate.fractional;
> +			src_rate = ((s64)src_rate_int << 31) + src_rate_frac;
> +			dst_rate_frac = pair_m2m->dst_rate.fractional;
> +			dst_rate = (((s64)dst_rate_int << 31) + dst_rate_frac) >> 20;
> +			do_div(src_rate, dst_rate);
> +			ratio_pre = src_rate;
> +
> +			src_rate = ((s64)src_rate_int << 31) + src_rate_frac;
> +			dst_rate_int = new_rate;
> +			dst_rate_frac = new_frac;
> +			dst_rate = (((s64)dst_rate_int << 31) + dst_rate_frac) >> 20;
> +			do_div(src_rate, dst_rate);
> +			ratio_cur = src_rate;
> +
> +			ratio_diff = ratio_cur - ratio_pre;
> +			/* convert ratio_diff to Q31*/
> +			asrc->m2m_set_ratio_mod(pair, ratio_diff << 11);

This is very similar to the other control. You really just want to pass
two rates (source and dest) and let that function calculate the ratio mod.

> +		}
> +
> +		pair_m2m->dst_rate.integer = new_rate;
> +		pair_m2m->dst_rate.fractional = new_frac;
> +
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct v4l2_ctrl_ops asrc_m2m_ctrl_ops = {
> +	.s_ctrl = asrc_m2m_op_s_ctrl,
> +};
> +
> +static const struct v4l2_ctrl_config asrc_src_rate_control = {
> +	.ops = &asrc_m2m_ctrl_ops,
> +	.id = V4L2_CID_ASRC_SOURCE_RATE,
> +	.name = "asrc source sample rate",

How about "Audio Source Sample Rate"?

But we want these controls as standard types (not driver specific), so
this should be added to drivers/media/v4l2-core/v4l2-ctrls-defs.c.

And if we just use an s64 to store the fixed point, then you can just
call v4l2_ctrl_new_std().

But you probably want to add some helper defines to split a fixed point
value into integer and fractional parts, and to construct one.

> +	.type = V4L2_CTRL_TYPE_FIXED_POINT,
> +	.min = 0,
> +	.max = 0x7fffffff,
> +	.def = 8000,
> +	.flags = V4L2_CTRL_FLAG_UPDATE,
> +};
> +
> +static const struct v4l2_ctrl_config asrc_dst_rate_control = {
> +	.ops = &asrc_m2m_ctrl_ops,
> +	.id = V4L2_CID_ASRC_DEST_RATE,
> +	.name = "asrc dest sample rate",
> +	.type = V4L2_CTRL_TYPE_FIXED_POINT,
> +	.min = 0,
> +	.max = 0x7fffffff,
> +	.def = 8000,
> +	.flags = V4L2_CTRL_FLAG_UPDATE,
> +};
> +
> +/* system callback for open() */
> +static int asrc_m2m_open(struct file *file)
> +{
> +	struct asrc_m2m *m2m = video_drvdata(file);
> +	struct fsl_asrc *asrc = m2m->pdata.asrc;
> +	struct video_device *vdev = video_devdata(file);
> +	struct fsl_asrc_pair *pair;
> +	struct asrc_pair_m2m *pair_m2m;
> +	int ret = 0;
> +
> +	if (mutex_lock_interruptible(&m2m->mlock))
> +		return -ERESTARTSYS;
> +
> +	pair = kzalloc(sizeof(*pair) + asrc->pair_priv_size, GFP_KERNEL);
> +	if (!pair) {
> +		ret = -ENOMEM;
> +		goto err_alloc_pair;
> +	}
> +
> +	pair_m2m = kzalloc(sizeof(*pair_m2m), GFP_KERNEL);
> +	if (!pair_m2m) {
> +		ret = -ENOMEM;
> +		goto err_alloc_pair_m2m;
> +	}
> +
> +	pair->private = (void *)pair + sizeof(struct fsl_asrc_pair);
> +	pair->asrc = asrc;
> +
> +	pair->buf_len[V4L_OUT] = ASRC_M2M_BUFFER_SIZE;
> +	pair->buf_len[V4L_CAP] = ASRC_M2M_BUFFER_SIZE;
> +
> +	pair->channels = 2;
> +	pair->rate[V4L_OUT] = 8000;
> +	pair->rate[V4L_CAP] = 8000;
> +	pair->sample_format[V4L_OUT] = SNDRV_PCM_FORMAT_S16_LE;
> +	pair->sample_format[V4L_CAP] = SNDRV_PCM_FORMAT_S16_LE;
> +
> +	init_completion(&pair->complete[V4L_OUT]);
> +	init_completion(&pair->complete[V4L_CAP]);
> +
> +	v4l2_fh_init(&pair_m2m->fh, vdev);
> +	v4l2_fh_add(&pair_m2m->fh);
> +	file->private_data = &pair_m2m->fh;
> +
> +	pair_m2m->pair = pair;
> +	pair_m2m->m2m = m2m;
> +	/* m2m context init */
> +	pair_m2m->fh.m2m_ctx = v4l2_m2m_ctx_init(m2m->m2m_dev, pair_m2m,
> +						 asrc_m2m_queue_init);
> +	if (IS_ERR(pair_m2m->fh.m2m_ctx)) {
> +		ret = PTR_ERR(pair_m2m->fh.m2m_ctx);
> +		goto err_ctx_init;
> +	}
> +
> +	v4l2_ctrl_handler_init(&pair_m2m->ctrl_handler, 2);
> +
> +	/* use V4L2_CID_GAIN for ratio update control */
> +	v4l2_ctrl_new_custom(&pair_m2m->ctrl_handler, &asrc_src_rate_control, NULL);
> +	v4l2_ctrl_new_custom(&pair_m2m->ctrl_handler, &asrc_dst_rate_control, NULL);
> +
> +	if (pair_m2m->ctrl_handler.error) {
> +		ret = pair_m2m->ctrl_handler.error;
> +		v4l2_ctrl_handler_free(&pair_m2m->ctrl_handler);
> +		goto err_ctrl_handler;
> +	}
> +
> +	pair_m2m->fh.ctrl_handler = &pair_m2m->ctrl_handler;
> +
> +	mutex_unlock(&m2m->mlock);
> +
> +	return 0;
> +
> +err_ctrl_handler:
> +	v4l2_m2m_ctx_release(pair_m2m->fh.m2m_ctx);
> +err_ctx_init:
> +	v4l2_fh_del(&pair_m2m->fh);
> +	v4l2_fh_exit(&pair_m2m->fh);
> +	kfree(pair_m2m);
> +err_alloc_pair_m2m:
> +	kfree(pair);
> +err_alloc_pair:
> +	mutex_unlock(&m2m->mlock);
> +	return ret;
> +}
> +
> +static int asrc_m2m_release(struct file *file)
> +{
> +	struct asrc_m2m *m2m = video_drvdata(file);
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(file->private_data);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +
> +	mutex_lock(&m2m->mlock);
> +	v4l2_ctrl_handler_free(&pair_m2m->ctrl_handler);
> +	v4l2_m2m_ctx_release(pair_m2m->fh.m2m_ctx);
> +	v4l2_fh_del(&pair_m2m->fh);
> +	v4l2_fh_exit(&pair_m2m->fh);
> +	kfree(pair_m2m);
> +	kfree(pair);
> +	mutex_unlock(&m2m->mlock);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_file_operations asrc_m2m_fops = {
> +	.owner          = THIS_MODULE,
> +	.open           = asrc_m2m_open,
> +	.release        = asrc_m2m_release,
> +	.poll           = v4l2_m2m_fop_poll,
> +	.unlocked_ioctl = video_ioctl2,
> +	.mmap           = v4l2_m2m_fop_mmap,
> +};
> +
> +static int asrc_m2m_querycap(struct file *file, void *priv,
> +			     struct v4l2_capability *cap)
> +{
> +	strscpy(cap->driver, "asrc m2m", sizeof(cap->driver));
> +	strscpy(cap->card, "asrc m2m", sizeof(cap->card));

This is rather ugly. It should at least mention imx, right?

> +	cap->device_caps = V4L2_CAP_STREAMING | V4L2_CAP_AUDIO_M2M;
> +	cap->capabilities = cap->device_caps | V4L2_CAP_DEVICE_CAPS;

You can drop this last line, that's done for you.

> +
> +	return 0;
> +}
> +
> +static int enum_fmt(struct v4l2_fmtdesc *f, u64 fmtbit)
> +{
> +	int i, num;
> +	struct asrc_fmt *fmt;
> +
> +	num = 0;
> +
> +	for (i = 0; i < NUM_FORMATS; ++i) {
> +		formats[i].format = convert_fourcc(formats[i].fourcc);
> +		if (pcm_format_to_bits(formats[i].format) & fmtbit) {
> +			if (num == f->index)
> +				break;
> +			/*
> +			 * Correct type but haven't reached our index yet,
> +			 * just increment per-type index
> +			 */
> +			++num;
> +		}
> +	}
> +
> +	if (i < NUM_FORMATS) {
> +		/* Format found */
> +		fmt = &formats[i];
> +		f->pixelformat = fmt->fourcc;
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int asrc_m2m_enum_fmt_aud_cap(struct file *file, void *fh,
> +				     struct v4l2_fmtdesc *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +
> +	return enum_fmt(f, m2m->pdata.fmt_out);
> +}
> +
> +static int asrc_m2m_enum_fmt_aud_out(struct file *file, void *fh,
> +				     struct v4l2_fmtdesc *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +
> +	return enum_fmt(f, m2m->pdata.fmt_in);
> +}
> +
> +static int asrc_m2m_g_fmt_aud_cap(struct file *file, void *fh,
> +				  struct v4l2_format *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +
> +	f->fmt.audio.channels = pair->channels;
> +	f->fmt.audio.buffersize = pair->buf_len[V4L_CAP];
> +	f->fmt.audio.audioformat = find_fourcc(pair->sample_format[V4L_CAP]);
> +
> +	return 0;
> +}
> +
> +static int asrc_m2m_g_fmt_aud_out(struct file *file, void *fh,
> +				  struct v4l2_format *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +
> +	f->fmt.audio.channels = pair->channels;
> +	f->fmt.audio.buffersize = pair->buf_len[V4L_OUT];
> +	f->fmt.audio.audioformat = find_fourcc(pair->sample_format[V4L_OUT]);
> +
> +	return 0;
> +}
> +
> +/* output for asrc */
> +static int asrc_m2m_s_fmt_aud_cap(struct file *file, void *fh,
> +				  struct v4l2_format *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct device *dev = &m2m->pdev->dev;
> +
> +	f->fmt.audio.audioformat = asrc_check_format(pair_m2m, OUT, f->fmt.audio.audioformat);
> +	f->fmt.audio.channels = asrc_check_channel(pair_m2m, OUT, f->fmt.audio.channels);
> +
> +	if (pair_m2m->channels[V4L_CAP] > 0 &&
> +	    pair_m2m->channels[V4L_CAP] != f->fmt.audio.channels) {
> +		dev_err(dev, "channels don't match for cap and out\n");
> +		return -EINVAL;
> +	}
> +
> +	pair_m2m->channels[V4L_CAP] = f->fmt.audio.channels;
> +	pair->channels = f->fmt.audio.channels;
> +	pair->sample_format[V4L_CAP] = find_format(f->fmt.audio.audioformat);
> +
> +	return 0;
> +}
> +
> +/* input for asrc */
> +static int asrc_m2m_s_fmt_aud_out(struct file *file, void *fh,
> +				  struct v4l2_format *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct device *dev = &m2m->pdev->dev;
> +
> +	f->fmt.audio.audioformat = asrc_check_format(pair_m2m, IN, f->fmt.audio.audioformat);
> +	f->fmt.audio.channels = asrc_check_channel(pair_m2m, IN, f->fmt.audio.channels);
> +	if (pair_m2m->channels[V4L_OUT] > 0 &&
> +	    pair_m2m->channels[V4L_OUT] != f->fmt.audio.channels) {
> +		dev_err(dev, "channels don't match for cap and out\n");
> +		return -EINVAL;
> +	}
> +
> +	pair_m2m->channels[V4L_OUT] = f->fmt.audio.channels;
> +	pair->channels = f->fmt.audio.channels;
> +	pair->sample_format[V4L_OUT] = find_format(f->fmt.audio.audioformat);
> +
> +	return 0;
> +}
> +
> +static int asrc_m2m_try_fmt_audio_cap(struct file *file, void *fh,
> +				      struct v4l2_format *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +
> +	f->fmt.audio.audioformat = asrc_check_format(pair_m2m, OUT, f->fmt.audio.audioformat);
> +	f->fmt.audio.channels = asrc_check_channel(pair_m2m, OUT, f->fmt.audio.channels);
> +
> +	return 0;
> +}
> +
> +static int asrc_m2m_try_fmt_audio_out(struct file *file, void *fh,
> +				      struct v4l2_format *f)
> +{
> +	struct asrc_pair_m2m *pair_m2m = asrc_m2m_fh_to_ctx(fh);
> +
> +	f->fmt.audio.audioformat = asrc_check_format(pair_m2m, IN, f->fmt.audio.audioformat);
> +	f->fmt.audio.channels = asrc_check_channel(pair_m2m, IN, f->fmt.audio.channels);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_ioctl_ops asrc_m2m_ioctl_ops = {
> +	.vidioc_querycap		= asrc_m2m_querycap,
> +
> +	.vidioc_enum_fmt_audio_cap	= asrc_m2m_enum_fmt_aud_cap,
> +	.vidioc_enum_fmt_audio_out	= asrc_m2m_enum_fmt_aud_out,
> +
> +	.vidioc_g_fmt_audio_cap		= asrc_m2m_g_fmt_aud_cap,
> +	.vidioc_g_fmt_audio_out		= asrc_m2m_g_fmt_aud_out,
> +
> +	.vidioc_s_fmt_audio_cap		= asrc_m2m_s_fmt_aud_cap,
> +	.vidioc_s_fmt_audio_out		= asrc_m2m_s_fmt_aud_out,
> +
> +	.vidioc_try_fmt_audio_cap	= asrc_m2m_try_fmt_audio_cap,
> +	.vidioc_try_fmt_audio_out	= asrc_m2m_try_fmt_audio_out,
> +
> +	.vidioc_qbuf			= v4l2_m2m_ioctl_qbuf,
> +	.vidioc_dqbuf			= v4l2_m2m_ioctl_dqbuf,
> +
> +	.vidioc_create_bufs		= v4l2_m2m_ioctl_create_bufs,
> +	.vidioc_prepare_buf		= v4l2_m2m_ioctl_prepare_buf,
> +	.vidioc_reqbufs			= v4l2_m2m_ioctl_reqbufs,
> +	.vidioc_querybuf		= v4l2_m2m_ioctl_querybuf,
> +	.vidioc_streamon		= v4l2_m2m_ioctl_streamon,
> +	.vidioc_streamoff		= v4l2_m2m_ioctl_streamoff,
> +	.vidioc_subscribe_event		= v4l2_ctrl_subscribe_event,
> +	.vidioc_unsubscribe_event	= v4l2_event_unsubscribe,
> +};
> +
> +/* dma complete callback */
> +static void asrc_input_dma_callback(void *data)
> +{
> +	struct fsl_asrc_pair *pair = (struct fsl_asrc_pair *)data;
> +
> +	complete(&pair->complete[V4L_OUT]);
> +}
> +
> +/* dma complete callback */
> +static void asrc_output_dma_callback(void *data)
> +{
> +	struct fsl_asrc_pair *pair = (struct fsl_asrc_pair *)data;
> +
> +	complete(&pair->complete[V4L_CAP]);
> +}
> +
> +/* config dma channel */
> +static int asrc_dmaconfig(struct asrc_pair_m2m *pair_m2m,
> +			  struct dma_chan *chan,
> +			  u32 dma_addr, dma_addr_t buf_addr, u32 buf_len,
> +			  int dir, int width)
> +{
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	struct fsl_asrc *asrc = pair->asrc;
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct device *dev = &m2m->pdev->dev;
> +	struct dma_slave_config slave_config;
> +	struct scatterlist sg[ASRC_M2M_SG_NUM];
> +	enum dma_slave_buswidth buswidth;
> +	unsigned int sg_len, max_period_size;
> +	int ret, i;
> +
> +	switch (width) {
> +	case 8:
> +		buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
> +		break;
> +	case 16:
> +		buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
> +		break;
> +	case 24:
> +		buswidth = DMA_SLAVE_BUSWIDTH_3_BYTES;
> +		break;
> +	case 32:
> +		buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
> +		break;
> +	default:
> +		dev_err(dev, "invalid word width\n");
> +		return -EINVAL;
> +	}
> +
> +	memset(&slave_config, 0, sizeof(slave_config));
> +	if (dir == V4L_OUT) {
> +		slave_config.direction = DMA_MEM_TO_DEV;
> +		slave_config.dst_addr = dma_addr;
> +		slave_config.dst_addr_width = buswidth;
> +		slave_config.dst_maxburst = asrc->m2m_get_maxburst(IN, pair);
> +	} else {
> +		slave_config.direction = DMA_DEV_TO_MEM;
> +		slave_config.src_addr = dma_addr;
> +		slave_config.src_addr_width = buswidth;
> +		slave_config.src_maxburst = asrc->m2m_get_maxburst(OUT, pair);
> +	}
> +
> +	ret = dmaengine_slave_config(chan, &slave_config);
> +	if (ret) {
> +		dev_err(dev, "failed to config dmaengine for %s task: %d\n",
> +			DIR_STR(dir), ret);
> +		return -EINVAL;
> +	}
> +
> +	max_period_size = rounddown(ASRC_M2M_PERIOD_SIZE, width * pair->channels / 8);
> +	/* scatter gather mode */
> +	sg_len = buf_len / max_period_size;
> +	if (buf_len % max_period_size)
> +		sg_len += 1;
> +
> +	sg_init_table(sg, sg_len);
> +	for (i = 0; i < (sg_len - 1); i++) {
> +		sg_dma_address(&sg[i]) = buf_addr + i * max_period_size;
> +		sg_dma_len(&sg[i]) = max_period_size;
> +	}
> +	sg_dma_address(&sg[i]) = buf_addr + i * max_period_size;
> +	sg_dma_len(&sg[i]) = buf_len - i * max_period_size;
> +
> +	pair->desc[dir] = dmaengine_prep_slave_sg(chan, sg, sg_len,
> +						  slave_config.direction,
> +						  DMA_PREP_INTERRUPT);
> +	if (!pair->desc[dir]) {
> +		dev_err(dev, "failed to prepare dmaengine for %s task\n", DIR_STR(dir));
> +		return -EINVAL;
> +	}
> +
> +	pair->desc[dir]->callback = ASRC_xPUT_DMA_CALLBACK(dir);
> +	pair->desc[dir]->callback_param = pair;
> +
> +	return 0;
> +}
> +
> +/* main function of converter */
> +static void asrc_m2m_device_run(void *priv)
> +{
> +	struct asrc_pair_m2m *pair_m2m = priv;
> +	struct fsl_asrc_pair *pair = pair_m2m->pair;
> +	struct asrc_m2m *m2m = pair_m2m->m2m;
> +	struct fsl_asrc *asrc = pair->asrc;
> +	struct device *dev = &m2m->pdev->dev;
> +	enum asrc_pair_index index = pair->index;
> +	struct vb2_v4l2_buffer *src_buf, *dst_buf;
> +	unsigned int out_buf_len;
> +	unsigned int cap_dma_len;
> +	unsigned int width;
> +	u32 fifo_addr;
> +	int ret;
> +
> +	src_buf = v4l2_m2m_next_src_buf(pair_m2m->fh.m2m_ctx);
> +	dst_buf = v4l2_m2m_next_dst_buf(pair_m2m->fh.m2m_ctx);
> +
> +	width = snd_pcm_format_physical_width(pair->sample_format[V4L_OUT]);
> +	fifo_addr = asrc->paddr + asrc->get_fifo_addr(IN, index);
> +	out_buf_len = vb2_get_plane_payload(&src_buf->vb2_buf, 0);
> +	if (out_buf_len < width * pair->channels / 8 ||
> +	    out_buf_len > ASRC_M2M_BUFFER_SIZE ||
> +	    out_buf_len % (width * pair->channels / 8)) {
> +		dev_err(dev, "out buffer size is error: [%d]\n", out_buf_len);
> +		goto end;
> +	}
> +
> +	/* dma config for output dma channel */
> +	ret = asrc_dmaconfig(pair_m2m,
> +			     pair->dma_chan[V4L_OUT],
> +			     fifo_addr,
> +			     vb2_dma_contig_plane_dma_addr(&src_buf->vb2_buf, 0),
> +			     out_buf_len, V4L_OUT, width);
> +	if (ret) {
> +		dev_err(dev, "out dma config error\n");
> +		goto end;
> +	}
> +
> +	width = snd_pcm_format_physical_width(pair->sample_format[V4L_CAP]);
> +	fifo_addr = asrc->paddr + asrc->get_fifo_addr(OUT, index);
> +	cap_dma_len = asrc->m2m_calc_out_len(pair, out_buf_len);
> +	if (cap_dma_len > 0 && cap_dma_len <= ASRC_M2M_BUFFER_SIZE) {
> +		/* dma config for capture dma channel */
> +		ret = asrc_dmaconfig(pair_m2m,
> +				     pair->dma_chan[V4L_CAP],
> +				     fifo_addr,
> +				     vb2_dma_contig_plane_dma_addr(&dst_buf->vb2_buf, 0),
> +				     cap_dma_len, V4L_CAP, width);
> +		if (ret) {
> +			dev_err(dev, "cap dma config error\n");
> +			goto end;
> +		}
> +	} else if (cap_dma_len > ASRC_M2M_BUFFER_SIZE) {
> +		dev_err(dev, "cap buffer size error\n");
> +		goto end;
> +	}
> +
> +	reinit_completion(&pair->complete[V4L_OUT]);
> +	reinit_completion(&pair->complete[V4L_CAP]);
> +
> +	/* Submit DMA request */
> +	dmaengine_submit(pair->desc[V4L_OUT]);
> +	dma_async_issue_pending(pair->desc[V4L_OUT]->chan);
> +	if (cap_dma_len > 0) {
> +		dmaengine_submit(pair->desc[V4L_CAP]);
> +		dma_async_issue_pending(pair->desc[V4L_CAP]->chan);
> +	}
> +
> +	asrc->m2m_start(pair);
> +
> +	if (!wait_for_completion_interruptible_timeout(&pair->complete[V4L_OUT], 10 * HZ)) {
> +		dev_err(dev, "out DMA task timeout\n");
> +		goto end;
> +	}
> +
> +	if (cap_dma_len > 0) {
> +		if (!wait_for_completion_interruptible_timeout(&pair->complete[V4L_CAP], 10 * HZ)) {
> +			dev_err(dev, "cap DMA task timeout\n");
> +			goto end;
> +		}
> +	}
> +
> +	/* read the last words from FIFO */
> +	asrc_read_last_fifo(pair, vb2_plane_vaddr(&dst_buf->vb2_buf, 0), &cap_dma_len);
> +	/* update payload length for capture */
> +	vb2_set_plane_payload(&dst_buf->vb2_buf, 0, cap_dma_len);
> +
> +end:
> +	src_buf = v4l2_m2m_src_buf_remove(pair_m2m->fh.m2m_ctx);
> +	dst_buf = v4l2_m2m_dst_buf_remove(pair_m2m->fh.m2m_ctx);
> +
> +	v4l2_m2m_buf_done(src_buf, VB2_BUF_STATE_DONE);
> +	v4l2_m2m_buf_done(dst_buf, VB2_BUF_STATE_DONE);
> +
> +	v4l2_m2m_job_finish(m2m->m2m_dev, pair_m2m->fh.m2m_ctx);
> +}
> +
> +static int asrc_m2m_job_ready(void *priv)
> +{
> +	struct asrc_pair_m2m *pair_m2m = priv;
> +
> +	if (v4l2_m2m_num_src_bufs_ready(pair_m2m->fh.m2m_ctx) > 0 &&
> +	    v4l2_m2m_num_dst_bufs_ready(pair_m2m->fh.m2m_ctx) > 0) {
> +		return 1;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_m2m_ops asrc_m2m_ops = {
> +	.job_ready = asrc_m2m_job_ready,
> +	.device_run = asrc_m2m_device_run,
> +};
> +
> +static int asrc_m2m_probe(struct platform_device *pdev)
> +{
> +	struct fsl_asrc_m2m_pdata *data = pdev->dev.platform_data;
> +	struct device *dev = &pdev->dev;
> +	struct asrc_m2m *m2m;
> +	int ret;
> +
> +	m2m = devm_kzalloc(dev, sizeof(struct asrc_m2m), GFP_KERNEL);
> +	if (!m2m)
> +		return -ENOMEM;
> +
> +	m2m->pdata = *data;
> +	m2m->pdev = pdev;
> +
> +	ret = v4l2_device_register(dev, &m2m->v4l2_dev);
> +	if (ret) {
> +		dev_err(dev, "failed to register v4l2 device\n");
> +		goto err_register;
> +	}
> +
> +	m2m->m2m_dev = v4l2_m2m_init(&asrc_m2m_ops);
> +	if (IS_ERR(m2m->m2m_dev)) {
> +		dev_err(dev, "failed to register v4l2 device\n");
> +		ret = PTR_ERR(m2m->m2m_dev);
> +		goto err_m2m;
> +	}
> +
> +	m2m->dec_vdev = video_device_alloc();
> +	if (!m2m->dec_vdev) {
> +		dev_err(dev, "failed to register v4l2 device\n");
> +		ret = -ENOMEM;
> +		goto err_vdev_alloc;
> +	}
> +
> +	mutex_init(&m2m->mlock);
> +
> +	m2m->dec_vdev->fops = &asrc_m2m_fops;
> +	m2m->dec_vdev->ioctl_ops = &asrc_m2m_ioctl_ops;
> +	m2m->dec_vdev->minor = -1;
> +	m2m->dec_vdev->release = video_device_release;
> +	m2m->dec_vdev->lock = &m2m->mlock; /* lock for ioctl serialization */
> +	m2m->dec_vdev->v4l2_dev = &m2m->v4l2_dev;
> +	m2m->dec_vdev->vfl_dir = VFL_DIR_M2M;
> +	m2m->dec_vdev->device_caps = V4L2_CAP_STREAMING | V4L2_CAP_AUDIO_M2M;
> +
> +	ret = video_register_device(m2m->dec_vdev, VFL_TYPE_AUDIO, -1);
> +	if (ret) {
> +		dev_err(dev, "failed to register video device\n");
> +		goto err_vdev_register;
> +	}
> +
> +	video_set_drvdata(m2m->dec_vdev, m2m);
> +	platform_set_drvdata(pdev, m2m);
> +	pm_runtime_enable(&pdev->dev);
> +
> +	return 0;
> +
> +err_vdev_register:
> +	video_device_release(m2m->dec_vdev);
> +err_vdev_alloc:
> +	v4l2_m2m_release(m2m->m2m_dev);
> +err_m2m:
> +	v4l2_device_unregister(&m2m->v4l2_dev);
> +err_register:
> +	return ret;
> +}
> +
> +static void asrc_m2m_remove(struct platform_device *pdev)
> +{
> +	struct asrc_m2m *m2m = platform_get_drvdata(pdev);
> +
> +	pm_runtime_disable(&pdev->dev);
> +	video_unregister_device(m2m->dec_vdev);
> +	video_device_release(m2m->dec_vdev);
> +	v4l2_m2m_release(m2m->m2m_dev);
> +	v4l2_device_unregister(&m2m->v4l2_dev);
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +/* suspend callback for m2m */
> +static int asrc_m2m_suspend(struct device *dev)
> +{
> +	struct asrc_m2m *m2m = dev_get_drvdata(dev);
> +	struct fsl_asrc *asrc = m2m->pdata.asrc;
> +	struct fsl_asrc_pair *pair;
> +	unsigned long lock_flags;
> +	int i;
> +
> +	for (i = 0; i < PAIR_CTX_NUM; i++) {
> +		spin_lock_irqsave(&asrc->lock, lock_flags);
> +		pair = asrc->pair[i];
> +		if (!pair || !pair->req_pair) {
> +			spin_unlock_irqrestore(&asrc->lock, lock_flags);
> +			continue;
> +		}
> +		if (!completion_done(&pair->complete[V4L_OUT])) {
> +			if (pair->dma_chan[V4L_OUT])
> +				dmaengine_terminate_all(pair->dma_chan[V4L_OUT]);
> +			asrc_input_dma_callback((void *)pair);
> +		}
> +		if (!completion_done(&pair->complete[V4L_CAP])) {
> +			if (pair->dma_chan[V4L_CAP])
> +				dmaengine_terminate_all(pair->dma_chan[V4L_CAP]);
> +			asrc_output_dma_callback((void *)pair);
> +		}
> +
> +		if (asrc->m2m_pair_suspend)
> +			asrc->m2m_pair_suspend(pair);
> +
> +		spin_unlock_irqrestore(&asrc->lock, lock_flags);
> +	}
> +
> +	return 0;
> +}
> +
> +static int asrc_m2m_resume(struct device *dev)
> +{
> +	struct asrc_m2m *m2m = dev_get_drvdata(dev);
> +	struct fsl_asrc *asrc = m2m->pdata.asrc;
> +	struct fsl_asrc_pair *pair;
> +	unsigned long lock_flags;
> +	int i;
> +
> +	for (i = 0; i < PAIR_CTX_NUM; i++) {
> +		spin_lock_irqsave(&asrc->lock, lock_flags);
> +		pair = asrc->pair[i];
> +		if (!pair || !pair->req_pair) {
> +			spin_unlock_irqrestore(&asrc->lock, lock_flags);
> +			continue;
> +		}
> +		if (asrc->m2m_pair_resume)
> +			asrc->m2m_pair_resume(pair);
> +
> +		spin_unlock_irqrestore(&asrc->lock, lock_flags);
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
> +static const struct dev_pm_ops asrc_m2m_pm_ops = {
> +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(asrc_m2m_suspend,
> +				      asrc_m2m_resume)
> +};
> +
> +static struct platform_driver asrc_m2m_driver = {
> +	.probe  = asrc_m2m_probe,
> +	.remove_new = asrc_m2m_remove,
> +	.driver = {
> +		.name = "fsl_asrc_m2m",
> +		.pm = &asrc_m2m_pm_ops,
> +	},
> +};
> +module_platform_driver(asrc_m2m_driver);
> +
> +MODULE_DESCRIPTION("Freescale ASRC M2M driver");
> +MODULE_LICENSE("GPL");

Regards,

	Hans