[PATCH 09/13] powerpc/5200: LocalPlus driver: smarter calculation of BPT, bytes per transfer

[Grant Likely]

On Tue, Dec 22, 2009 at 12:08 AM, Roman Fietze
<roman.fietze at telemotive.de> wrote:
>
> Signed-off-by: Roman Fietze <roman.fietze at telemotive.de>
> ---
>  arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c |   33 +++++++++++++++----------
>  1 files changed, 20 insertions(+), 13 deletions(-)
>
> diff --git a/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c b/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c
> index 48f2b4f..21b2a40 100644
> --- a/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c
> +++ b/arch/powerpc/platforms/52xx/mpc52xx_lpbfifo.c
> @@ -80,11 +80,11 @@ static inline int mpc52xx_lpbfifo_is_poll_dma(int flags)
>  */
>  static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
>  {
> -       size_t transfer_size = req->size - req->pos;
> +       size_t tc = req->size - req->pos;
>        struct bcom_bd *bd;
>        void __iomem *reg;
>        u32 *data;
> -       u32 bit_fields;
> +       u32 control;

Changing the name of these two variables makes it hard to review the
functional change.  A lot of unrelated housekeeping gets interwoven.

>        int rflags = req->flags;
>
>        /* Set and clear the reset bits; is good practice in User Manual */
> @@ -93,10 +93,10 @@ static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
>        /* Set width, chip select and READ mode */
>        out_be32(&lpbfifo.regs->start_address, req->offset + req->pos);
>
> -       /* Set CS and BPT */
> -       bit_fields = MPC52xx_SCLPC_CONTROL_CS(req->cs) | 0x8;
> +       /* Setup CS */
> +       control = MPC52xx_SCLPC_CONTROL_CS(req->cs);
>        if (!(mpc52xx_lpbfifo_is_write(rflags)))
> -               bit_fields |= MPC52xx_SCLPC_CONTROL_RWB_RECEIVE;        /* read mode */
> +               control |= MPC52xx_SCLPC_CONTROL_RWB_RECEIVE;   /* read mode */
>
>        if (!mpc52xx_lpbfifo_is_dma(rflags)) {
>                /* While the FIFO can be setup for transfer sizes as
> @@ -112,10 +112,10 @@ static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
>                 * The last block of data will be received with the
>                 * flush bit set. This avoids stale read data.
>                 */
> -               if (transfer_size > 512)
> -                       transfer_size = 512;
> +               if (tc > 512)
> +                       tc = 512;
>                else if (!(mpc52xx_lpbfifo_is_write(rflags)))
> -                       bit_fields |= MPC52xx_SCLPC_CONTROL_FLUSH;
> +                       control |= MPC52xx_SCLPC_CONTROL_FLUSH;
>
>                /* Load the FIFO with data */
>                if (mpc52xx_lpbfifo_is_write(rflags)) {
> @@ -123,7 +123,7 @@ static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
>
>                        reg = &lpbfifo.regs->fifo_data;
>                        data = req->data + req->pos;
> -                       for (i = 0; i < transfer_size; i += 4)
> +                       for (i = 0; i < tc; i += 4)
>                                out_be32(reg, *data++);
>                }
>
> @@ -136,7 +136,7 @@ static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
>                /* In DMA mode we can always set the flush bit to avoid
>                 * stale read data. */
>                if (!(mpc52xx_lpbfifo_is_write(rflags)))
> -                       bit_fields |= MPC52xx_SCLPC_CONTROL_FLUSH;
> +                       control |= MPC52xx_SCLPC_CONTROL_FLUSH;
>
>                /* Choose the correct direction
>                 *
> @@ -173,15 +173,17 @@ static void mpc52xx_lpbfifo_kick(struct mpc52xx_lpbfifo_request *req)
>                out_be32(&lpbfifo.regs->enable, MPC52xx_SCLPC_ENABLE_AIE | MPC52xx_SCLPC_ENABLE_NIE | MPC52xx_SCLPC_ENABLE_ME);
>
>                bd = bcom_prepare_next_buffer(lpbfifo.bcom_cur_task);
> -               bd->status = transfer_size;
> +               bd->status = tc;
>                bd->data[0] = req->data_dma + req->pos;
>                bcom_submit_next_buffer(lpbfifo.bcom_cur_task, NULL);
>        }
>
> -       out_be32(&lpbfifo.regs->control, bit_fields);
> +       /* Setup BPT. tc is already screened and a multiple of 4 */
> +       control |= tc & 7 ? 4 : 8;
> +       out_be32(&lpbfifo.regs->control, control);

The calculation looks correct.  However, why isn't the transfer size
calculated up by the /* Setup CS and BPT */ comment?  I don't think it
needs to be down here.

>
>        /* Set packet size and kick it off */
> -       out_be32(&lpbfifo.regs->packet_size.packet_size, MPC52xx_SCLPC_PACKET_SIZE_RESTART | transfer_size);
> +       out_be32(&lpbfifo.regs->packet_size.packet_size, MPC52xx_SCLPC_PACKET_SIZE_RESTART | tc);
>        if (mpc52xx_lpbfifo_is_dma(rflags))
>                bcom_enable(lpbfifo.bcom_cur_task);
>  }
> @@ -395,6 +397,11 @@ int mpc52xx_lpbfifo_submit(struct mpc52xx_lpbfifo_request *req)
>        if (!lpbfifo.regs)
>                return -ENODEV;
>
> +       /* The gen bd BestComm task currently only allows an increment
> +        * of 4 */
> +       if (!req->size || req->size & 0x03)
> +               return -EINVAL;
> +
>        spin_lock_irqsave(&lpbfifo.lock, flags);
>
>        /* If the req pointer is already set, then a transfer is in progress */
> --
> 1.6.5.5
>
>
>
> --
> Roman Fietze                Telemotive AG Büro Mühlhausen
> Breitwiesen                              73347 Mühlhausen
> Tel.: +49(0)7335/18493-45        http://www.telemotive.de
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev at lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.