Re: drm/i915/backlight: Remove DP_EDP_BACKLIGHT_AUX_ENABLE_CAP check for DPCD backlight
Michał Grzelak <[email protected]>
| Newsgroups | org.freedesktop.lists.intel-gfx,org.freedesktop.lists.intel-xe |
|---|---|
| Message-ID | <[email protected]> |
On Thu, 16 Jul 2026, Suraj Kandpal wrote:
> Turns out Some panels allow only backlight AUX based backlight
nits:
s/Some/some/
s/backlight AUX/AUX/
> by just setting the DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP and
> not setting the DP_EDP_BACKLIGHT_AUX_ENABLE_CAP.
> If we make DP_EDP_BACKLIGHT_AUX_ENABLE_CAP a necessity for AUX
> based DPCD backlight these panels loose the ability to manipulate
> backlight via AUX, specially ones with no PWM controller.
maybe: s/specially/especially/
> Remove this check from function so that panels who do not advertise
> DP_EDP_BACKLIGHT_AUX_ENABLE_CAP but advertise
> DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP are able to manipulate
> backlight again.
>
> Fixes: ed8be780bdbc ("drm/i915/backlight: Fix VESA backlight possible check condition")
> Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/work_items/16507
> Signed-off-by: Suraj Kandpal <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> index 7a6c07f6aaeb..83245cb738e5 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -619,8 +619,7 @@ check_if_vesa_backlight_possible(struct intel_dp *intel_dp)
> * Since we only support Fully AUX Based VESA Backlight interface make sure
> * backlight enable is possible via AUX along with backlight adjustment
> */
Wondering if the comment above needs any adjustment?
Either way:
Reviewed-by: Michał Grzelak <[email protected]>
BR,
Michał
> - if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP &&
> - intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP))
> + if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP))
> return false;
>
> ret = drm_dp_dpcd_read_byte(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN, &bit_min);
>