On Fri, Aug 20, 2021 at 08:26:14PM +0300, Ville Syrjälä wrote:
> On Fri, Aug 20, 2021 at 03:52:59PM +0800, Kai-Heng Feng wrote:
> > Users reported that after commit 2bbd6dba84d4 ("drm/i915: Try to use
> > fast+narrow link on eDP again and fall back to the old max strategy on
> > failure"), the screen starts to have wobbly effect.
> >
> > Commit a5c936add6a2 ("drm/i915/dp: Use slow and wide link training for
> > everything") doesn't help either, that means the affected eDP 1.2 panels
> > only work with max params.
> >
> > So use max params for panels < eDP 1.4 as Windows does to solve the
> > issue.
> >
> > v3:
> > - Do the eDP rev check in intel_edp_init_dpcd()
> >
> > v2:
> > - Check eDP 1.4 instead of DPCD 1.1 to apply max params
> >
> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3714
> > Fixes: 2bbd6dba84d4 ("drm/i915: Try to use fast+narrow link on eDP again
> > and fall back to the old max strategy on failure")
> > Fixes: a5c936add6a2 ("drm/i915/dp: Use slow and wide link training for
> > everything")
> > Suggested-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
> > Signed-off-by: Kai-Heng Feng <kai.heng.f...@canonical.com>
>
> Slapped a cc:stable on it and pushed to drm-intel-next. Thanks.
Since I got a strange failure on CI_DIF_604 that I don't see on CI_DIF_603,
I'm avoiding the display patches. This one and also
dab1b47e57e0 ("drm/i915/dp: return proper DPRX link training result")
I know, it is probably the other one, but I had to remove both patches for
now and I'm not confident the CI will allow me to test with this one alone.
If we have -rc8 I will check again later. Otherwise we will have to send
to the stable mailing list later.
>
> > ---
> > drivers/gpu/drm/i915/display/intel_dp.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 75d4ebc669411..e0dbd35ae7bc0 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -2445,11 +2445,14 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)
> > */
> > if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_DPCD_REV,
> > intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
> > - sizeof(intel_dp->edp_dpcd))
> > + sizeof(intel_dp->edp_dpcd)) {
> > drm_dbg_kms(&dev_priv->drm, "eDP DPCD: %*ph\n",
> > (int)sizeof(intel_dp->edp_dpcd),
> > intel_dp->edp_dpcd);
> >
> > + intel_dp->use_max_params = intel_dp->edp_dpcd[0] < DP_EDP_14;
> > + }
> > +
> > /*
> > * This has to be called after intel_dp->edp_dpcd is filled, PSR checks
> > * for SET_POWER_CAPABLE bit in intel_dp->edp_dpcd[1]
> > --
> > 2.32.0
>
> --
> Ville Syrjälä
> Intel
