Re: [U-Boot] [PATCH 2/2] usb: gadget: fotg210: EP0 fifo empty indication is non-reliable

[Marek Vasut]

On Wednesday, December 18, 2013 at 08:24:49 AM, Kuo-Jung Su wrote:
> From: Kuo-Jung Su <dant...@faraday-tech.com>
> 
> Because the EP0 fifo empty indication is non-reliable,
> an extra delay is necessary to avoid data corruption while
> handling packets with size greater than 64 bytes.
> 
> This workaround should be applied to all hardware revisions.
> 
> Signed-off-by: Kuo-Jung Su <dant...@faraday-tech.com>
> CC: Marek Vasut <ma...@denx.de>
> ---
>  drivers/usb/gadget/fotg210.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/usb/gadget/fotg210.c b/drivers/usb/gadget/fotg210.c
> index e3a61cc..14bfec6 100644
> --- a/drivers/usb/gadget/fotg210.c
> +++ b/drivers/usb/gadget/fotg210.c
> @@ -245,6 +245,7 @@ static int fotg210_dma(struct fotg210_ep *ep, struct
> fotg210_request *req) if (ep->id == 0) {
>                       /* Wait until cx/ep0 fifo empty */
>                       fotg210_cxwait(chip, CXFIFO_CXFIFOE);
> +                     udelay_masked(1);

Why don't you use regular udelay() here please ? Also, how exactly does the 
delay help solving the unreliability problem please?

>                       writel(DMAFIFO_CX, &regs->dma_fifo);
>               } else {
>                       /* Wait until epx fifo empty */

Best regards,
Marek Vasut
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