From mboxrd@z Thu Jan 1 00:00:00 1970 From: wlf Subject: Re: [PATCH v3 2/2] usb: dwc2: fix isoc split in transfer with no data Date: Tue, 8 May 2018 15:01:32 +0800 Message-ID: References: <1525748846-7767-1-git-send-email-william.wu@rock-chips.com> <1525748846-7767-3-git-send-email-william.wu@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Doug Anderson , William Wu Cc: hminas@synopsys.com, felipe.balbi@linux.intel.com, Greg Kroah-Hartman , Sergei Shtylyov , =?UTF-8?Q?Heiko_St=c3=bcbner?= , LKML , linux-usb@vger.kernel.org, "open list:ARM/Rockchip SoC..." , Frank Wang , =?UTF-8?B?6buE5rab?= , "daniel.meng" , John Youn , =?UTF-8?B?546L5b6B5aKe?= , zsq@rock-chips.com, =?UTF-8?B?6Kix5ZiJ6YqY?= , Stan Tsui , =?UTF-8?B?U3BydWNlIFd1ICjlkLPlu7rli7Mp?= , Martin.Tsai@quantatw.com, Kevin.Shai@quantatw.com List-Id: linux-rockchip.vger.kernel.org Dear Doug, 在 2018年05月08日 13:13, Doug Anderson 写道: > Hi, > > On Mon, May 7, 2018 at 8:07 PM, William Wu wrote: >> If isoc split in transfer with no data (the length of DATA0 >> packet is zero), we can't simply return immediately. Because >> the DATA0 can be the first transaction or the second transaction >> for the isoc split in transaction. If the DATA0 packet with no >> data is in the first transaction, we can return immediately. >> But if the DATA0 packet with no data is in the second transaction >> of isoc split in transaction sequence, we need to increase the >> qtd->isoc_frame_index and giveback urb to device driver if needed, >> otherwise, the MDATA packet will be lost. >> >> A typical test case is that connect the dwc2 controller with an >> usb hs Hub (GL852G-12), and plug an usb fs audio device (Plantronics >> headset) into the downstream port of Hub. Then use the usb mic >> to record, we can find noise when playback. >> >> In the case, the isoc split in transaction sequence like this: >> >> - SSPLIT IN transaction >> - CSPLIT IN transaction >> - MDATA packet (176 bytes) >> - CSPLIT IN transaction >> - DATA0 packet (0 byte) >> >> This patch use both the length of DATA0 and qtd->isoc_split_offset >> to check if the DATA0 is in the second transaction. >> >> Signed-off-by: William Wu >> --- >> Changes in v3: >> - Remove "qtd->isoc_split_offset = 0" in the if test >> >> Changes in v2: >> - Modify the commit message >> >> drivers/usb/dwc2/hcd_intr.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c >> index ba6fd852..3003594 100644 >> --- a/drivers/usb/dwc2/hcd_intr.c >> +++ b/drivers/usb/dwc2/hcd_intr.c >> @@ -930,9 +930,8 @@ static int dwc2_xfercomp_isoc_split_in(struct dwc2_hsotg *hsotg, >> frame_desc = &qtd->urb->iso_descs[qtd->isoc_frame_index]; >> len = dwc2_get_actual_xfer_length(hsotg, chan, chnum, qtd, >> DWC2_HC_XFER_COMPLETE, NULL); >> - if (!len) { >> + if (!len && !qtd->isoc_split_offset) { >> qtd->complete_split = 0; >> - qtd->isoc_split_offset = 0; >> return 0; >> } > This looks fine to me now, but as per my comments on the previous > version I don't think I've dug through this problem enough to add my > Reviewed-by tag. I'll assume that John or someone with more knowledge > of the USB protocol than I have will Review / Ack. Thanks very much for your review. Let's wait for other experts' suggestion. > > -Doug > > >