On Thu, Mar 19, 2020 at 03:20:50PM -0700, Manasi Navare wrote:
> On Thu, Mar 19, 2020 at 06:38:42PM +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> >
> > Some new eDP panels don't like to operate at the max parameters, and
> > instead we need to go for an optimal confiugration. That unfortunately
> > doesn't work with older eDP panels which are generally only guaranteed
> > to work at the max parameters.
> >
> > To solve these two conflicting requirements let's start with the optimal
> > setup, and if that fails we start again with the max parameters. The
> > downside is probably an extra modeset when we switch strategies but
> > I don't see a good way to avoid that.
> >
> > For a bit of history we first tried to go for the fast+narrow in
> > commit 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config
> > fast and narrow"). but that had to be reverted due to regression
> > on older panels in commit f11cb1c19ad0 ("drm/i915/dp: revert back
> > to max link rate and lane count on eDP"). So now we try to get
> > the best of both worlds by using both strategies.
> >
> > v2: Deal with output_bpp and uapi vs. hw state split
> > Reword some comments
> >
> > Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
> > Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> > Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> > Cc: Albert Astals Cid <aacid@xxxxxxx> # v5.0 backport
> > Cc: Emanuele Panigati <ilpanich@xxxxxxxxx> # v5.0 backport
> > Cc: Matteo Iervasi <matteoiervasi@xxxxxxxxx> # v5.0 backport
> > Cc: Timo Aaltonen <tjaalton@xxxxxxxxxx>
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=105267
> > References: https://bugs.freedesktop.org/show_bug.cgi?id=109959
> > References: https://gitlab.freedesktop.org/drm/intel/issues/272
> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> This approach looks good to me to fallback to max parameters if
> it fails the first time.
>
> > ---
> > .../drm/i915/display/intel_display_types.h | 1 +
> > drivers/gpu/drm/i915/display/intel_dp.c | 74 ++++++++++++++++---
> > 2 files changed, 66 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > index 5e00e611f077..ffde0d4af23c 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > @@ -1258,6 +1258,7 @@ struct intel_dp {
> > bool link_trained;
> > bool has_audio;
> > bool reset_link_params;
> > + bool use_max_params;
> > u8 dpcd[DP_RECEIVER_CAP_SIZE];
> > u8 psr_dpcd[EDP_PSR_RECEIVER_CAP_SIZE];
> > u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index ef2e06e292d5..85abcce492ca 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -465,6 +465,12 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
> > {
> > int index;
> >
> > + if (intel_dp_is_edp(intel_dp) && !intel_dp->use_max_params) {
> > + DRM_DEBUG_KMS("Retrying Link training for eDP with max parameters\n");
> > + intel_dp->use_max_params = true;
> > + return 0;
> > + }
>
> We need to remove the current check for intel_dp_can_link_train_fallback_for_edp() right?
No. Why do you think it needs to be removed?
--
Ville Syrjälä
Intel
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