linux-kernel - Re: [PATCH v5 2/4] drm/amd/display: Add support for minimum backlight quirk

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Message-ID: <3940dab1-ec3d-4d14-a43e-8821b9f6a1de@amd.com>
Date: Thu, 22 Aug 2024 08:34:34 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Thomas Weißschuh <linux@...ssschuh.net>
Cc: Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Harry Wentland <harry.wentland@....com>, Leo Li <sunpeng.li@....com>,
 Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
 Matt Hartley <matt.hartley@...il.com>, Kieran Levin <ktl@...mework.net>,
 Hans de Goede <hdegoede@...hat.com>,
 Jani Nikula <jani.nikula@...ux.intel.com>, Xinhui Pan <Xinhui.Pan@....com>,
 Jonathan Corbet <corbet@....net>, amd-gfx@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 Dustin Howett <dustin@...ett.net>, linux-doc@...r.kernel.org
Subject: Re: [PATCH v5 2/4] drm/amd/display: Add support for minimum backlight
 quirk

On 8/22/2024 01:14, Thomas Weißschuh wrote:
> On 2024-08-21 15:54:14+0000, Mario Limonciello wrote:
>> On 8/18/2024 01:56, Thomas Weißschuh wrote:
>>> Not all platforms provide correct PWM backlight capabilities through ATIF.
>>
>> I don't think correct is an accurate term here.  How about 'optimial'?
> 
> Looks typoed to me :-)

heh.

> 
> What about this?
> 
> Not all platforms provide the full range of PWM backlight capabilities
> supported by the hardware through ATIF.

Sounds great, thanks!
> 
> 
>>> Use the generic drm panel minimum backlight quirk infrastructure to
>>> override the capabilities where necessary.
>>>
>>> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
>>> Tested-by: Dustin L. Howett <dustin@...ett.net>
>>
>> The code looks fine to me but please wait for an ack from someone on the AMD
>> display team.
>>
>> Also, I would like to see comments about the testing with panel power
>> savings enabled to avoid a conflict.
> 
> Ack.
> 
>>
>> Reviewed-by: Mario Limonciello <mario.limonciello@....com>
>>> ---
>>>    drivers/gpu/drm/amd/amdgpu/Kconfig                |  1 +
>>>    drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 ++++++++++
>>>    2 files changed, 11 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/Kconfig b/drivers/gpu/drm/amd/amdgpu/Kconfig
>>> index 0051fb1b437f..655c10aef2e3 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/Kconfig
>>> +++ b/drivers/gpu/drm/amd/amdgpu/Kconfig
>>> @@ -23,6 +23,7 @@ config DRM_AMDGPU
>>>    	select DRM_BUDDY
>>>    	select DRM_SUBALLOC_HELPER
>>>    	select DRM_EXEC
>>> +	select DRM_PANEL_BACKLIGHT_QUIRKS
>>>    	# amdgpu depends on ACPI_VIDEO when ACPI is enabled, for select to work
>>>    	# ACPI_VIDEO's dependencies must also be selected.
>>>    	select INPUT if ACPI
>>> 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 983a977632ff..056960ea335c 100644
>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>> @@ -93,6 +93,7 @@
>>>    #include <drm/drm_fourcc.h>
>>>    #include <drm/drm_edid.h>
>>>    #include <drm/drm_eld.h>
>>> +#include <drm/drm_utils.h>
>>>    #include <drm/drm_vblank.h>
>>>    #include <drm/drm_audio_component.h>
>>>    #include <drm/drm_gem_atomic_helper.h>
>>> @@ -3333,6 +3334,8 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
>>>    	struct drm_connector *conn_base;
>>>    	struct amdgpu_device *adev;
>>>    	struct drm_luminance_range_info *luminance_range;
>>> +	const struct drm_edid *drm_edid;
>>> +	int min_input_signal_override;
>>>    	if (aconnector->bl_idx == -1 ||
>>>    	    aconnector->dc_link->connector_signal != SIGNAL_TYPE_EDP)
>>> @@ -3367,6 +3370,13 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
>>>    		caps->aux_min_input_signal = 0;
>>>    		caps->aux_max_input_signal = 512;
>>>    	}
>>> +
>>> +	drm_edid = drm_edid_alloc(aconnector->edid,
>>> +				  EDID_LENGTH * (aconnector->edid->extensions + 1));
>>> +	min_input_signal_override = drm_get_panel_min_brightness_quirk(drm_edid);
>>> +	drm_edid_free(drm_edid);
>>> +	if (min_input_signal_override >= 0)
>>> +		caps->min_input_signal = min_input_signal_override;
>>>    }
>>>    void amdgpu_dm_update_connector_after_detect(
>>>
>>