[PATCH v2] usb: fsl_udc: errata - postpone freeing current dTD

[Felipe Balbi]

Hi,

On Mon, May 21, 2012 at 08:57:22AM +0200, Christoph Fritz wrote:
> USB controller may access a wrong address for the dTD (endpoint transfer
> descriptor) and then hang. This happens a lot when doing tests with
> g_ether module and iperf, a tool for measuring maximum TCP and UDP
> bandwidth.
> 
> This hardware bug is explained in detail by errata number 2858 for i.MX23:
> http://cache.freescale.com/files/dsp/doc/errata/IMX23CE.pdf
> 
> All (?) SOCs with an IP from chipidea suffer from this problem.
> mv_udc_core fixes this bug by commit daec765.  There still may be
> unfixed drivers.
> 
> Signed-off-by: Christoph Fritz <chf.fritz at googlemail.com>
> Signed-off-by: Christian Hemp <c.hemp at phytec.de>
> ---
>  drivers/usb/gadget/fsl_udc_core.c |   15 ++++++++++++++-
>  1 files changed, 14 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/usb/gadget/fsl_udc_core.c b/drivers/usb/gadget/fsl_udc_core.c
> index 55abfb6..72f2139 100644
> --- a/drivers/usb/gadget/fsl_udc_core.c
> +++ b/drivers/usb/gadget/fsl_udc_core.c
> @@ -65,6 +65,8 @@ static struct usb_sys_interface *usb_sys_regs;
>  /* it is initialized in probe()  */
>  static struct fsl_udc *udc_controller = NULL;
>  
> +static struct ep_td_struct *last_free_td;

I don't want to see global variables anymore. In fact, please convert
this to the new udc_start()/udc_stop() calls and use the generic
map/unmap routines.

That'll help you get rid of a bunch of useless code on the driver. After
that you should remove all <asm/*> header includes and drop the ARCH
dependency.

You can also drop the big-/little-endian helpers as you can make use of
generic writel()/readl() routines.

Please make sure these series comes in with enough time to reach v3.6
merge window in about 3 months.

You can put this fix together on that series after you drop the global.

-- 
balbi
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