| Message ID | 20210804152408.584823-1-kai.heng.feng@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915/dp: Use max params for older panels | expand |
On Wed, Aug 04, 2021 at 11:24:02PM +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 panels only > work with max params. Unfortunate that the link training apparently passes with the bad params and thus the automagic use_max_params fallback doesn't kick in :( > > The panels are all DP 1.1 ones, so apply max params to them to resolve > the issue. > > 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") > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com> > --- > drivers/gpu/drm/i915/display/intel_dp.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c > index 75d4ebc669411..e64bab4b016e1 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp.c > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > @@ -1330,14 +1330,16 @@ intel_dp_compute_link_config(struct intel_encoder *encoder, > limits.min_bpp = intel_dp_min_bpp(pipe_config->output_format); > limits.max_bpp = intel_dp_max_bpp(intel_dp, pipe_config); > > - if (intel_dp->use_max_params) { > + if (intel_dp->use_max_params || > + intel_dp->dpcd[DP_DPCD_REV] <= DP_DPCD_REV_11) { IIRC Windows uses the optimal link rate only for EPD_REV>=1.4. We should probably do the same the minimize future headaches. > /* > * Use the maximum clock and number of lanes the eDP panel > * advertizes being capable of in case the initial fast > - * optimal params failed us. The panels are generally > - * designed to support only a single clock and lane > - * configuration, and typically on older panels these > - * values correspond to the native resolution of the panel. > + * optimal params failed us or the panel is DP 1.1 or earlier. > + * The panels are generally designed to support only a single > + * clock and lane configuration, and typically on older panels > + * these values correspond to the native resolution of the > + * panel. > */ > limits.min_lane_count = limits.max_lane_count; > limits.min_clock = limits.max_clock; > -- > 2.31.1
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index 75d4ebc669411..e64bab4b016e1 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -1330,14 +1330,16 @@ intel_dp_compute_link_config(struct intel_encoder *encoder, limits.min_bpp = intel_dp_min_bpp(pipe_config->output_format); limits.max_bpp = intel_dp_max_bpp(intel_dp, pipe_config); - if (intel_dp->use_max_params) { + if (intel_dp->use_max_params || + intel_dp->dpcd[DP_DPCD_REV] <= DP_DPCD_REV_11) { /* * Use the maximum clock and number of lanes the eDP panel * advertizes being capable of in case the initial fast - * optimal params failed us. The panels are generally - * designed to support only a single clock and lane - * configuration, and typically on older panels these - * values correspond to the native resolution of the panel. + * optimal params failed us or the panel is DP 1.1 or earlier. + * The panels are generally designed to support only a single + * clock and lane configuration, and typically on older panels + * these values correspond to the native resolution of the + * panel. */ limits.min_lane_count = limits.max_lane_count; limits.min_clock = limits.max_clock;
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 panels only work with max params. The panels are all DP 1.1 ones, so apply max params to them to resolve the issue. 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") Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com> --- drivers/gpu/drm/i915/display/intel_dp.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)