[PATCH 0/2] Add backlight-pwm-passthru in analogix DP driver
seanpaul at chromium.org
Fri Mar 16 09:50:21 PDT 2018
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
> 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 at chromium.org>
> 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(+)
Sean Paul, Software Engineer, Google / Chromium OS
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