On Thu, Mar 15, 2018 at 07:56:57PM -0700, Alexandru M Stan wrote: > I noticed that the backlight on the ASUS Chromebook Flip C101 (bob) is > flickering. > > We're sending it a high frequency pwm signal, but the EDP panel decided to > "parse" the signal, read the duty cycle, then make its own signal that > it sends to the LEDs. > > So even though we send a nice high refresh rate at 1200Hz, the panel backlight > flickers at 200Hz (which is not even divisible by the 60Hz refresh rate). > > The fix for that is to enable the EDP_BACKLIGHT_FREQ_PWM_PIN_PASSTHRU bit from > the DPCD EDP registers. This makes the panel actually follow the signal > we're giving it. > > This series includes the optional dt binding to enable this fix > (backlight-pwm-passthru) and the corresponding code in the analogix > drm/bridge driver. > Thanks for sending these patches! With Archit and Daniel's comments addressed, feel free to add my Reviewed-by: Sean Paul <seanpaul@xxxxxxxxxxxx> > > Alexandru M Stan (2): > dt-bindings: analogix-dp: Add backlight-pwm-passthru > drm/bridge: analogix: Enable EDP_BACKLIGHT_FREQ_PWM_PIN_PASSTHRU > > .../bindings/display/bridge/analogix_dp.txt | 4 ++ > drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 48 ++++++++++++++++++++++ > drivers/gpu/drm/bridge/analogix/analogix_dp_core.h | 1 + > 3 files changed, 53 insertions(+) > > -- > 2.13.5 > -- Sean Paul, Software Engineer, Google / Chromium OS -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
