On Sun, Oct 30, 2022 at 5:26 AM Filip Moc <dev@xxxxxxx> wrote: > > There are some devices on which amdgpu won't allow user to set brightness > to sufficiently low values even though the hardware would support it just > fine. > > This usually happens in two cases when either configuration of brightness > levels via ACPI/ATIF is not available and amdgpu falls back to defaults > (currently 12 for minimum level) which may be too high for some devices or > even the configuration via ATIF is available but the minimum brightness > level provided by the manufacturer is set to unreasonably high value. > > In either case user can use this new module parameter to adjust the > minimum allowed backlight brightness level. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=203439 > Signed-off-by: Filip Moc <dev@xxxxxxx> Does your system require an override and if so, what is it? It would be good to add a quirk for your system as well so that other users of the same system wouldn't need to manually figure out an apply the settings. Alex > --- > drivers/gpu/drm/amd/amdgpu/amdgpu.h | 3 +++ > drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 15 +++++++++++++++ > drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 15 +++++++++++++++ > 3 files changed, 33 insertions(+) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h > index 0e6ddf05c23c..c5445402c49d 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h > @@ -200,6 +200,9 @@ extern uint amdgpu_dc_debug_mask; > extern uint amdgpu_dc_visual_confirm; > extern uint amdgpu_dm_abm_level; > extern int amdgpu_backlight; > +#ifdef CONFIG_DRM_AMD_DC > +extern int amdgpu_backlight_override_min[]; > +#endif > 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 16f6a313335e..f2fb549ac52f 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c > @@ -43,6 +43,7 @@ > #include "amdgpu_irq.h" > #include "amdgpu_dma_buf.h" > #include "amdgpu_sched.h" > +#include "amdgpu_dm.h" > #include "amdgpu_fdinfo.h" > #include "amdgpu_amdkfd.h" > > @@ -853,6 +854,20 @@ int amdgpu_backlight = -1; > MODULE_PARM_DESC(backlight, "Backlight control (0 = pwm, 1 = aux, -1 auto (default))"); > module_param_named(backlight, amdgpu_backlight, bint, 0444); > > +/** > + * DOC: backlight_min (array of int) > + * Override minimum allowed backlight brightness signal (per display). > + * Must be less than the maximum brightness signal. > + * Negative value means no override. > + * > + * Defaults to all -1 (no override on any display). > + */ > +#ifdef CONFIG_DRM_AMD_DC > +int amdgpu_backlight_override_min[AMDGPU_DM_MAX_NUM_EDP] = {[0 ... (AMDGPU_DM_MAX_NUM_EDP-1)] = -1}; > +MODULE_PARM_DESC(backlight_min, "Override minimum backlight brightness signal (0..max-1, -1 = no override (default))"); > +module_param_array_named(backlight_min, amdgpu_backlight_override_min, int, NULL, 0444); > +#endif > + > /** > * 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 eb4ce7216104..e2c36ba93d05 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -3911,6 +3911,21 @@ static void amdgpu_dm_update_backlight_caps(struct amdgpu_display_manager *dm, > dm->backlight_caps[bl_idx].min_input_signal = AMDGPU_DM_DEFAULT_MIN_BACKLIGHT; > dm->backlight_caps[bl_idx].max_input_signal = AMDGPU_DM_DEFAULT_MAX_BACKLIGHT; > #endif > + > + if (amdgpu_backlight_override_min[bl_idx] >= 0) { > + if (amdgpu_backlight_override_min[bl_idx] < dm->backlight_caps[bl_idx].max_input_signal) { > + DRM_INFO("amdgpu: backlight[%i]: overriding minimum brightness from %i to %i\n", > + bl_idx, > + dm->backlight_caps[bl_idx].min_input_signal, > + amdgpu_backlight_override_min[bl_idx]); > + dm->backlight_caps[bl_idx].min_input_signal = amdgpu_backlight_override_min[bl_idx]; > + } else { > + DRM_ERROR("amdgpu: backlight[%i]: minimum brightness override (%i) is not below maximum (%i)\n", > + bl_idx, > + amdgpu_backlight_override_min[bl_idx], > + dm->backlight_caps[bl_idx].max_input_signal); > + } > + } > } > > static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps, > > base-commit: d8c03bfe146fd5e081a252cd34f3f12ca0255357 > -- > 2.30.2 >
