[PATCH 2/2] drm/amd/display: Add aux_backlight module option

[Alex Deucher]

On Wed, Feb 3, 2021 at 7:42 AM Takashi Iwai <tiwai at suse.de> wrote:
>
> There seem devices that don't work with the aux channel backlight
> control.  For allowing such users to test with the other backlight
> control method, provide a new module option, aux_backlight, to specify
> enabling or disabling the aux backport support explicitly.  As
> default, the aux support is detected by the hardware capability.
>
> BugLink: https://bugzilla.opensuse.org/show_bug.cgi?id=1180749
> BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1438
> Signed-off-by: Takashi Iwai <tiwai at suse.de>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h               | 1 +
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c           | 4 ++++
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++
>  3 files changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 5993dd0fdd8e..4793cd5e69f9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -179,6 +179,7 @@ extern uint amdgpu_smu_memory_pool_size;
>  extern uint amdgpu_dc_feature_mask;
>  extern uint amdgpu_dc_debug_mask;
>  extern uint amdgpu_dm_abm_level;
> +extern int amdgpu_aux_backlight;
>  extern struct amdgpu_mgpu_info mgpu_info;
>  extern int amdgpu_ras_enable;
>  extern uint amdgpu_ras_mask;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 7169fb5e3d9c..5b66822da954 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -777,6 +777,10 @@ uint amdgpu_dm_abm_level;
>  MODULE_PARM_DESC(abmlevel, "ABM level (0 = off (default), 1-4 = backlight reduction level) ");
>  module_param_named(abmlevel, amdgpu_dm_abm_level, uint, 0444);
>
> +int amdgpu_aux_backlight = -1;
> +MODULE_PARM_DESC(aux_backlight, "Aux backlight control (0 = off, 1 = on, default auto)");
> +module_param_named(aux_backlight, amdgpu_aux_backlight, bint, 0444);

I'd suggest making this something more generic like "backlight" and
make -1 auto, 0 pwm, 1 aux.  That way we can handle potential future
types more cleanly.

Alex


> +
>  /**
>   * DOC: tmz (int)
>   * Trusted Memory Zone (TMZ) is a method to protect data being written
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index fb62886ae013..6ad384ef61b8 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -2209,6 +2209,9 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
>             caps->ext_caps->bits.hdr_aux_backlight_control == 1)
>                 caps->aux_support = true;
>
> +       if (amdgpu_aux_backlight >= 0)
> +               caps->aux_support = amdgpu_aux_backlight;
> +
>         /* From the specification (CTA-861-G), for calculating the maximum
>          * luminance we need to use:
>          *      Luminance = 50*2**(CV/32)
> --
> 2.26.2
>
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