[Intel-gfx] [PATCH] drm/i915/dp: return proper DPRX link training result

[Saarinen, Jani]

Hi, 

> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces at lists.freedesktop.org> On Behalf Of Imre Deak
> Sent: maanantai 30. elokuuta 2021 9.45
> To: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Lee, Shawn C <shawn.c.lee at intel.com>; Almahallawy, Khaled
> <khaled.almahallawy at intel.com>; intel-gfx at lists.freedesktop.org; Chiou, Cooper
> <cooper.chiou at intel.com>; Tseng, William <william.tseng at intel.com>
> Subject: Re: [Intel-gfx] [PATCH] drm/i915/dp: return proper DPRX link training result
> 
> On Sat, Aug 21, 2021 at 02:02:03AM +0300, Imre Deak wrote:
> > On Sat, Aug 21, 2021 at 01:20:04AM +0300, Ville Syrjälä wrote:
> > > On Wed, Aug 18, 2021 at 07:17:12PM +0300, Imre Deak wrote:
> > > > On Wed, Aug 18, 2021 at 06:09:43PM +0300, Lee, Shawn C wrote:
> > > > > On Tue, 2021-07-07, Lee Shawn C <shawn.c.lee at intel.com> wrote:
> > > > > >On Tue, 2021-07-07, Almahallawy, Khaled <khaled.almahallawy at intel.com>
> wrote:
> > > > > >>I believe Imre's LT fallback:
> > > > > >>https://github.com/ideak/linux/commits/linktraining-fallback-fix  and
> Chrome user space fix:
> > > > > >>https://chromium-review.googlesource.com/c/chromium/src/+/3003
> > > > > >>487 should address Chrome concerns for LT failure and LTTPRs
> > > > > >>
> > > > > >
> > > > > >Thanks for comment! The new fallback patch should help on this DPRX
> problem.
> > > > > >One more thing. If driver did not handle DPRX link train failed properly.
> > > > > >It would impact link layer compliance test case in below.
> > > > > >
> > > > > >400.3.1.3
> > > > > >400.3.1.4
> > > > > >400.3.1.6
> > > > > >400.3.1.12
> > > > > >400.3.1.13
> > > > > >400.3.1.14
> > > > > >
> > > > > >Best regards,
> > > > > >Shawn
> > > > > >
> > > > >
> > > > > Hi all, before Imre's patch series land on upstream driver. The
> > > > > link train failed handling works for LTTPR only. But DPRX does
> > > > > not. Could you please consider to have this change as temporary solution?
> Thanks!
> > > >
> > > > I sent already fixing this, see
> > > > https://lore.kernel.org/intel-gfx/20201027133600.3656665-1-imre.de
> > > > ak at intel.com/
> > > >
> > > > but it fell through the cracks. Applied now your patch, thanks.
> > >
> > > We seem to have a tgl that fails consistently at DPRX link training:
> > > https://intel-gfx-ci.01.org/tree/drm-tip/fi-tgl-1115g4.html
> > >
> > > Previously the error went unnoticed.
> >
> > Yea, didn't notice this. Can't see anything obvious, besides that it's
> > a DPCD rev 1.1 monitor, so maybe not compatible with LTTPRs. I follow
> > up if I find something.
> 
> Power cycling the machine and replugging the monitor and Type C dongle and native
> DP cable fixed it. So, it could be a flaky connection (unlikely, because detection
> worked), or the port in a stuck state even across warm-reboots. The latter would
> mean the machine wasn't power cycled for a long time and that's likely because the
> pstore kernel didn't boot (grub failed to load it due to a missing initrd).
Thanks Imre for checking. 

> 
> One possibile root cause is the TypeC PHY getting stuck across warm reboots issue
> (and nothing recovering it besides a power-cycle), that was fixed by
> 151ec347b06a2fb ("drm/i915: Force a TypeC PHY disconnect during
> suspend/shutdown")
> 
> I'll re-check this after more CI testruns.
Ack but now looks indeed green again. 

> 
> > > --
> > > Ville Syrjälä
> > > Intel