[Intel-gfx] [PATCH] drm/i915/dp: Remove aux xfer timeout debug message

[Chris Wilson]

Quoting Almahallawy, Khaled (2020-12-31 01:24:34)
> On Wed, 2020-12-30 at 16:02 -0800, Matt Roper wrote:
> > On Wed, Dec 30, 2020 at 10:37:42AM +0000, Chris Wilson wrote:
> > > The timeouts are frequent and expected. We will complain if we
> > > retry so
> > > often as to lose patience and give up, so the cacophony from
> > > individual
> > > complaints is redundant.
> > > 
> > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > 
> > Reviewed-by: Matt Roper <matthew.d.roper at intel.com>
> > 
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_dp.c | 2 --
> > >  1 file changed, 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > > b/drivers/gpu/drm/i915/display/intel_dp.c
> > > index 8ae769b18879..704e4cebf7f3 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > > @@ -1613,8 +1613,6 @@ intel_dp_aux_xfer(struct intel_dp *intel_dp,
> > >     /* Timeouts occur when the device isn't connected, so they're
> > >      * "normal" -- don't fill the kernel log with these */
> > >     if (status & DP_AUX_CH_CTL_TIME_OUT_ERROR) {
> > > -           drm_dbg_kms(&i915->drm, "%s: timeout (status
> > > 0x%08x)\n",
> > > -                       intel_dp->aux.name, status);
> 
> AUX timeout logs are very important for TGL TCSS Display debugging. We
> actually can get AUX timeout when the display is connected for the
> following reasons:
> * If AUX orientation is not configured correctly in BIOS
> * If USB3 dock is downgraded to USB2 and SBU/AUX lines are disabled
> * When LTTPR/Retimer started to act funny and not configured correctly
> by EC
> * When we have a bug in the PMC mux configuration because of bug in the
> following files: drivers/usb/typec/mux/intel_pmc_mux.c and
> drivers/platform/x86/intel_scu_ipc.c
> * When user space is not cleanly disconnected all MST connectors for
> disconnected MST hub with 2+ display. We will be left with enabled
> pipes although the cable is disconnected and next connect of type-c
> display will give aux timeout: 
>   ** User space fix in Chrome: 
> https://chromium-review.googlesource.com/c/chromium/src/+/2512550/ 
>   ** WA in driver: https://patchwork.freedesktop.org/patch/395901/ 
> 
> These logs are especially important for Chrome based platforms with
> type-C. Seeing these logs we can know who is screwing up (TCSS driver,
> CB, or EC).

Then capture the information you require to analyse your failures.
Flooding the debug log makes debugging everything else much, much harder.
-Chris