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Message-ID: <CAD=FV=X3f9tHLY+5NJTBxegsc1PYz5MhomC7MNNSjL-vA8DCWg@mail.gmail.com>
Date: Mon, 7 May 2018 22:13:41 -0700
From: Doug Anderson <dianders@...gle.com>
To: William Wu <william.wu@...k-chips.com>
Cc: hminas@...opsys.com, felipe.balbi@...ux.intel.com,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
Heiko Stübner <heiko@...ech.de>,
LKML <linux-kernel@...r.kernel.org>, linux-usb@...r.kernel.org,
"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
Frank Wang <frank.wang@...k-chips.com>,
黄涛 <huangtao@...k-chips.com>,
"daniel.meng" <daniel.meng@...k-chips.com>,
John Youn <John.Youn@...opsys.com>,
王征增 <wzz@...k-chips.com>,
zsq@...k-chips.com,
許嘉銘 <Allen.Hsu@...ntatw.com>,
Stan Tsui <StanTsui@...en.com>,
Spruce Wu (吳建勳) <Spruce.Wu@...ntatw.com>,
Martin.Tsai@...ntatw.com, Kevin.Shai@...ntatw.com,
Mon-Jer Wu (吳孟哲)
<Mon-Jer.Wu@...ntatw.com>,
Claud Chang (張恭築)
<Claud.Chang@...ntatw.com>,
San Lin (林建菱) <San.Lin@...ntatw.com>,
Ren.Kuo@...ntatw.com, "David H.T. Wang" <davidhtwang@...en.com>,
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Steven Cheng <stevencheng@...en.com>,
Tom Chen <tomchen@...en.com>, donchang@...en.com,
milesschofield@...en.com
Subject: Re: [PATCH v3 2/2] usb: dwc2: fix isoc split in transfer with no data
Hi,
On Mon, May 7, 2018 at 8:07 PM, William Wu <william.wu@...k-chips.com> 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 <william.wu@...k-chips.com>
> ---
> 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.
-Doug
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