Hello Harry, thank you for your response. > amdgpu.backlight_min=2:-1 almost :-) Array elements in module parameters are separated by commas not colons. So for cmdline it should look like this: amdgpu.backlight_min=2,-1 Though you can just drop the ,-1 relying on kernel leaving the rest of array untouched. Which I would recommend as there is no point for user to follow AMDGPU_DM_MAX_NUM_EDP. Only when you need to override some other display than display 0 then you may need to use -1. E.g. backlight_min=-1,2 overrides display 1 to min backlight=2 while keeping display 0 with no override. When amdgpu is loaded as a kernel module, backlight_min can also be passed as a parameter to modprobe, e.g.: modprobe backlight_min=2 So in that case you probably want to add something like options amdgpu backlight_min=2 to /etc/modprobe.d/amdgpu.conf (and also run update-initramfs if amdgpu is loaded by initramfs). I'll add some examples to commit message in v2. Filip V Mon, Oct 31, 2022 at 10:24:25AM -0400, Harry Wentland napsal(a): > On 2022-10-29 15:13, Filip Moc 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. > > > > Thanks for this patch and covering all the bases. > > It might be useful to have an example in the commit description on > how to set the array property. I assume it looks like this if I > wanted to set the first device to a minimum of 2 and leave the default > for the 2nd one: > > amdgpu.backlight_min=2:-1 > > Either way, this patch is > Reviewed-by: Harry Wentland <harry.wentland@xxxxxxx> > > Harry > > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=203439>> > > Signed-off-by: Filip Moc <dev@xxxxxxx> > > --- > > 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 >
