From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Fri, 20 Dec 2013 09:17:37 +0100 Subject: [U-Boot] [PATCH 2/2] usb: gadget: fotg210: EP0 fifo empty indication is non-reliable In-Reply-To: References: <1387351489-2008-1-git-send-email-dantesu@gmail.com> <201312190817.39742.marex@denx.de> Message-ID: <201312200917.37522.marex@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On Friday, December 20, 2013 at 04:45:39 AM, Kuo-Jung Su wrote: > 2013/12/19 Marek Vasut : > > On Thursday, December 19, 2013 at 08:07:00 AM, Kuo-Jung Su wrote: > >> 2013/12/19 Marek Vasut : > >> > On Thursday, December 19, 2013 at 01:50:55 AM, Kuo-Jung Su wrote: > >> >> 2013/12/18 Marek Vasut : > >> >> > On Wednesday, December 18, 2013 at 08:24:49 AM, Kuo-Jung Su wrote: > >> >> >> From: Kuo-Jung Su > >> >> >> > >> >> >> 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 > >> >> >> CC: Marek Vasut > >> >> >> --- > >> >> >> > >> >> >> 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? > >> >> > >> >> 1. No specific reason at all, I'll use regular udelay() in next > >> >> version. > >> >> > >> >> :) > >> >> > >> >> 2. The fifo size of ep0 is 64 bytes, and my driver is supposed to > >> >> make sure the fifo empty > >> >> > >> >> before filling up the fifo. However there is a hardware bug that > >> >> > >> >> the fifo empty indication is somehow > >> >> > >> >> a bit earlier than fifo reset. So if I don't add an extra delay > >> >> > >> >> here, the data might be corrupted (i.e., 1 byte missing.) > >> >> > >> >> And after a couple of tests, it looks like that 1 usec is good > >> >> > >> >> enough for this. > >> > > >> > Ick, but I guess you guys know the IP blocks' sourcecode. > >> > >> Yes, but I don't have the access permission , and I'm not a member of > >> the IP verification team...... > >> > >> Anyway I'll try to call the IP owner see if he's willing to do FPGA > >> verification. > > > > Would be nice, but I dont mind picking it even without such confirmation. > > Thanks! > > > > Best regards, > > Marek Vasut > > Sorry, this bug is schedule as a lowest priority. > Because I'm the only one who have this issue in Faraday. > i.e., I'm the only one to configure the FOTG210 as an Ethernet gadget, > while others always configure it as an bulk-only mass storage gadget. > And only under Ethernet gadget mode, we'll have to handle EP0 packets > with size greater than 64Bytes. > > So I can't clearly figure out the root cause of the buggy Faraday FOTG210. OK, don't worry about it. Thanks for checking! Best regards,