linux-kernel - Re: [PATCH 1/1] drm/amd/display: Add quirk to force backlight type on some TUXEDO devices

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Message-ID: <293be5bc-11ad-49b8-a549-864ce4016f14@tuxedocomputers.com>
Date: Tue, 24 Jun 2025 07:42:50 +0200
From: Werner Sembach <wse@...edocomputers.com>
To: "Limonciello, Mario" <Mario.Limonciello@....com>,
 Rodrigo Siqueira <siqueira@...lia.com>
Cc: "Wentland, Harry" <Harry.Wentland@....com>,
 "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
 "Deucher, Alexander" <Alexander.Deucher@....com>,
 "Koenig, Christian" <Christian.Koenig@....com>,
 "airlied@...il.com" <airlied@...il.com>, "simona@...ll.ch"
 <simona@...ll.ch>,
 "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
 "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "Hung, Alex" <Alex.Hung@....com>, "Wheeler, Daniel" <Daniel.Wheeler@....com>
Subject: Re: [PATCH 1/1] drm/amd/display: Add quirk to force backlight type on
 some TUXEDO devices

Hi Mario,

Am 23.06.25 um 21:42 schrieb Limonciello, Mario:
> On 6/23/25 2:13 PM, Rodrigo Siqueira wrote:
>> On 06/23, Werner Sembach wrote:
>>> gentle bump
>>>
>>> Am 09.04.25 um 18:27 schrieb Werner Sembach:
>>>> The display backlight on TUXEDO Polaris AMD Gen2 and Gen3 with panels
>>>> BOE 2420 and BOE 2423 must be forced to pwn controlled to be able to
>>>> control the brightness.
>>>>
>>>> This could already be archived via a module parameter, but this patch adds
>>>> a quirk to apply this by default on the mentioned device + panel
>>>> combinations.
>>>>
>>>> Signed-off-by: Werner Sembach <wse@...edocomputers.com>
>>>> Cc: stable@...r.kernel.org
>>>> ---
>>>>     .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 32 ++++++++++++++++++-
>>>>     1 file changed, 31 insertions(+), 1 deletion(-)
>>>>
>>>> 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 39df45f652b32..2bad6274ad8ff 100644
>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>> @@ -1625,11 +1625,13 @@ static bool dm_should_disable_stutter(struct pci_dev *pdev)
>>>>     struct amdgpu_dm_quirks {
>>>>     	bool aux_hpd_discon;
>>>>     	bool support_edp0_on_dp1;
>>>> +	bool boe_2420_2423_bl_force_pwm;
>>>>     };
>>>>     static struct amdgpu_dm_quirks quirk_entries = {
>>>>     	.aux_hpd_discon = false,
>>>> -	.support_edp0_on_dp1 = false
>>>> +	.support_edp0_on_dp1 = false,
>>>> +	.boe_2420_2423_bl_force_pwm = false
>>>>     };
>>>>     static int edp0_on_dp1_callback(const struct dmi_system_id *id)
>>>> @@ -1644,6 +1646,12 @@ static int aux_hpd_discon_callback(const struct dmi_system_id *id)
>>>>     	return 0;
>>>>     }
>>>> +static int boe_2420_2423_bl_force_pwm_callback(const struct dmi_system_id *id)
>>>> +{
>>>> +	quirk_entries.boe_2420_2423_bl_force_pwm = true;
>>>> +	return 0;
>>>> +}
>>>> +
>>>>     static const struct dmi_system_id dmi_quirk_table[] = {
>>>>     	{
>>>>     		.callback = aux_hpd_discon_callback,
>>>> @@ -1722,6 +1730,20 @@ static const struct dmi_system_id dmi_quirk_table[] = {
>>>>     			DMI_MATCH(DMI_PRODUCT_NAME, "HP EliteBook 665 16 inch G11 Notebook PC"),
>>>>     		},
>>>>     	},
>>>> +	{
>>>> +		// TUXEDO Polaris AMD Gen2
>>>> +		.callback = boe_2420_2423_bl_force_pwm_callback,
>>>> +		.matches = {
>>>> +			DMI_MATCH(DMI_BOARD_NAME, "GMxNGxx"),
>>>> +		},
>>>> +	},
>>>> +	{
>>>> +		// TUXEDO Polaris AMD Gen3
>>>> +		.callback = boe_2420_2423_bl_force_pwm_callback,
>>>> +		.matches = {
>>>> +			DMI_MATCH(DMI_BOARD_NAME, "GMxZGxx"),
>>>> +		},
>>>> +	},
>>>>     	{}
>>>>     	/* TODO: refactor this from a fixed table to a dynamic option */
>>>>     };
>>>> @@ -3586,6 +3608,7 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
>>>>     	struct amdgpu_device *adev;
>>>>     	struct drm_luminance_range_info *luminance_range;
>>>>     	int min_input_signal_override;
>>>> +	u32 panel;
>>>>     	if (aconnector->bl_idx == -1 ||
>>>>     	    aconnector->dc_link->connector_signal != SIGNAL_TYPE_EDP)
>>>> @@ -3610,6 +3633,13 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
>>>>     		caps->aux_support = false;
>>>>     	else if (amdgpu_backlight == 1)
>>>>     		caps->aux_support = true;
>>>> +	else if (amdgpu_backlight == -1 &&
>>>> +		 quirk_entries.boe_2420_2423_bl_force_pwm) {
>>>> +		panel = drm_edid_get_panel_id(aconnector->drm_edid);
>>>> +		if (panel == drm_edid_encode_panel_id('B', 'O', 'E', 0x0974) ||
>>>> +		    panel == drm_edid_encode_panel_id('B', 'O', 'E', 0x0977))
>>>> +			caps->aux_support = false;
>>>> +	}
>> It lgtm,
>>
>> Additionally, I believe this is safe to merge since it only affects a
>> specific device. Perhaps display folks would like to include this as
>> part of this week's promotion? Anyway, Cc other devs from the display.
>>
>> Reviewed-by: Rodrigo Siqueira <siqueira@...lia.com>
> That's a bit odd that aux based B/L control wouldn't work.  Are these
> both OLED panels?  What debugging have you done thus far with them?
> What kernel base?
>
> Could you repro on 6.16-rc3?

Sadly our archive is missing this panel + device combination. This patch is 
based on our install script that sets this fix via boot parameters since the 
release of these devices.

So the quirk is field proven, but I can't actively test it anymore.

Best regards,

Werner

>
>>>>     	if (caps->aux_support)
>>>>     		aconnector->dc_link->backlight_control_type = BACKLIGHT_CONTROL_AMD_AUX;