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

18 Dec 2013

On Wednesday, December 18, 2013 at 08:24:49 AM, Kuo-Jung Su wrote:
...
From: Kuo-Jung Su dantesu@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 dantesu@faraday-tech.com
CC: Marek Vasut marex@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

    