linux-kernel - Re: [RFC] usb: dwc2: hcd: fix split schedule issue

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Message-ID: <2B3535C5ECE8B5419E3ECBE30077290901DC3C8CA4@US01WEMBX2.internal.synopsys.com>
Date:	Thu, 12 Nov 2015 04:29:52 +0000
From:	John Youn <John.Youn@...opsys.com>
To:	Doug Anderson <dianders@...omium.org>,
	Yunzhi Li <lyz@...k-chips.com>
CC:	John Youn <John.Youn@...opsys.com>,
	Julius Werner <jwerner@...gle.com>,
	Dinh Nguyen <dinguyen@...nsource.altera.com>,
	"Kaukab, Yousaf" <yousaf.kaukab@...el.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	wulf <wulf@...k-chips.com>,
	Kever Yang <kever.yang@...k-chips.com>,
	caesar <caesar.wang@...k-chips.com>,
	Tao Huang <huangtao@...k-chips.com>,
	rockchip-discuss <rockchip-discuss@...omium.org>
Subject: Re: [RFC] usb: dwc2: hcd: fix split schedule issue

On 11/11/2015 4:22 PM, Doug Anderson wrote:
> John,
> 
> On Fri, Nov 6, 2015 at 2:04 AM, Yunzhi Li <lyz@...k-chips.com> wrote:
>> hi John ,
>>
>>   As we talked yesterday, I tried to fix the split schedule sequence. This
>> patch will
>> avoid scheduling SSPLIT-IN packet for another device between
>> SSPLIT-OUT-begin and
>> SSPLIT-OUT-end, now the keyboard and Jebra audio speaker could work together
>> well, but
>> I'm not sure if this is exactly the right way to schedule split transfers
>> and if there
>> is any dide effect with this patch. Please help review this patch. Thanks.
>>
>>> Fix dwc2 split schedule sequence issue. Not schedule a SSPLIT_IN
>>> packet between SSPLIT-begin and SSPLIT-end.
>>>
>>> Signed-off-by: Yunzhi Li <lyz@...k-chips.com>
>>> ---
>>>   drivers/usb/dwc2/hcd.c | 4 ++++
>>>   1 file changed, 4 insertions(+)
> 
> Did you have any thoughts on this patch?  Although this patch didn't
> fix the problems I was seeing with the Microsoft Wireless Keyboard
> (see the patch I sent out earlier which does seem to fix it), I can
> confirm that in a different setup (HUB goes to USB audio + mouse) that
> this patch does fix some problems.
> 
> That being said, it feels to me like a band-aid rather than an actual
> fix (I'm talking out of my rear end, though, since my USB experience
> is lacking at best).  It feels like perhaps we're just not keeping
> track the xact_pos correctly, but of course I don't know that for
> sure...
> 
> Anyway, just fishing...  ;)
> 
> -Doug
> 

Hi Doug,

I also feel it is not quite right as the SSPLIT should be able to
happen during the SSPLIT of another device. I tried to reproduce
and see the same scheduling but don't see any hang due to it.

Yunzhi, any details on what kind of hub and keyboard you are
using? I have the same Jabra 410 speaker.

Regards,
John




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