On Thu, Aug 19, 2021 at 01:14:55AM +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.
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.syrjala@linux.intel.com 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..f87fad78f1a9f 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->edp_dpcd[0] < DP_EDP_14) {
I think we're going to need a is_edp check here or else we'll always take this path on extenral DP when edp_dpcd[] is zeroed.
Hmm. Maybe just stick intel_dp->use_max_params = intel_dp->edp_dpcd[0] < DP_EDP_14; into intel_edp_init_dpcd()?
/* * 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 EDP rev is earlier than 1.4.* 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.-- 2.32.0