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

[Yunzhi Li]

Hi John

å 2015/11/12 12:29, John Youn åé:
> On 11/11/2015 4:22 PM, Doug Anderson wrote:
> > John,
> >
> > On Fri, Nov 6, 2015 at 2:04 AM, Yunzhi Li <lyz@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
> > > > ---
> > > >    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.
You could use a single tt hub and any stander keyboard or mouse to 
reproduce this issue
1. connect hub keyboard and audio speaker
2. play any sound
3. then the keyboard stop working

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