On Thu, 2017-07-20 at 10:06 +0000, Tc, Jenny wrote: > > >> With older panels, AUX pin for backlight doesn't work. > > > > What evidence do you have to back up that claim? > > Debugging further it's found that the panel I am having doesn't support AUX Backlight. > > cat /sys/kernel/debug/dri/0/eDP-1/i915_dpcd > ... > 0701: bb ff 00 00 > .... > > With below change its working for my panel. But doesn't address issue reported in > https://bugs.freedesktop.org/show_bug.cgi?id=101619 which seems to have a wrong DPCD data. > Since we don't have a proper fix for all panels, I agree for revert. > > intel_dp_aux_display_control_heuristic(struct intel_connector *connector) > struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base); > uint8_t reg_val; > > + /* Panel dosn't support enabling AUX Backlight control */ > + if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP)) { > + return false; > + } AUX backlight brightness control should work even without AUX enable capability. > /* Panel doesn't support adjusting backlight brightness via PWN pin */ > if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) > return true; > > > >> On some panels, this causes backlight issues on S3 resume. > > > > > > What is it that we are missing in the resume path? > > > > > >> Enable the > > >> feature only for eDP1.4 or later. > > > > > > I can't find the eDP 1.4 requirement in the spec. Regional brightness > > > control was added in eDP 1.4, but we don't enable that. My concern is > > > we might be missing a real fix by ignoring < eDP 1.4 panels. > > > > Agreed. > > > > This has been going on too long now, with no real effort to get at the roots of > > the problem. The right approach is to revert the regressing commits now, > > and start over. Reverts posted [1]. > > > > BR, > > Jani. > > > > [1] https://patchwork.freedesktop.org/series/27623/ > > > > > > > > > > >> > > >> Fix-suggested-by: Puthikorn Voravootivat <puthik@xxxxxxxxxxxx> > > > > > > 1. Please use the "Fixes" tag to refer to the commit that introduced > > > the code you are fixing. > > > 2. The "Suggested-by" tag is more common to give credits to the person > > > who suggested the fix. > > > 3. Please use the "Bugzilla" tag to point to the bug that David > > > reported. > > > > > > > > >> Signed-off-by: Jenny TC <jenny.tc@xxxxxxxxx> > > >> --- > > >> drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 6 +++++- > > >> 1 file changed, 5 insertions(+), 1 deletion(-) > > >> > > >> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > > >> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > > >> index b25cd88..421f31f 100644 > > >> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > > >> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c > > >> @@ -292,7 +292,7 @@ static int intel_dp_aux_setup_backlight(struct > > intel_connector *connector, > > >> * via PWM pin or using AUX is better than using PWM pin. > > >> * > > >> * The heuristic to determine that using AUX pin is better than > > >> using PWM pin is > > >> - * that the panel support any of the feature list here. > > >> + * that the panel is eDP 1.4 or later and support any of the feature > > >> + list here > > >> * - Regional backlight brightness adjustment > > >> * - Backlight PWM frequency set > > >> * - More than 8 bits resolution of brightness level @@ -310,6 > > >> +310,10 @@ static int intel_dp_aux_setup_backlight(struct > > intel_connector *connector, > > >> if (!(intel_dp->edp_dpcd[2] & > > DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) > > >> return true; > > >> > > >> + /* Enable this for eDP 1.4 panel or later. */ > > >> + if (intel_dp->edp_dpcd[0] < DP_EDP_14) > > >> + return false; > > >> + > > >> /* Panel supports regional backlight brightness adjustment */ > > >> if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_GENERAL_CAP_3, > > >> ®_val) != 1) { > > > > -- > > Jani Nikula, Intel Open Source Technology Center > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
