[PATCH v2 1/2] drm/nouveau/disp: add backlight for ada lovelace

[Angelo Dureghello]

Hi Lyude,

thanks a lot for your reply,

On 15/04/24 6:54 PM, Lyude Paul wrote:
> Hm. Could you share some logs with drm.debug=0x116? I'm a bit confused
> because I would have thought that we were already probing for eDP
> backlights seeing as I added support for them at one point?
>
> (I hope this isn't the point I learn I actually forgot to add support
> for them :P)
>
i am attaching 2 dmesg logs with drm.debug=0x116, with these 2 patches
applied to mainstream, and without them.

https://pastecode.io/s/fyjkky6y
https://pastecode.io/s/gdf8v3e3


Note, this laptop (Lenovo Legion 5 Pro 16ARX8) has 2 video cards,
amd (cpu built-in), and additional nvidia, it can work in "switchable"
mode, where amndgpu backlight works, and in discrete mode (as now),
using only nvidia gpu.

Main issue is that in nouveau_backlight.c
nouveau_backlight_init() is actually not considering ADA LOVELACE in
the main switch/case. So execution falls back to acpi backlight,
that for this laptop does not work at all (tried vendor, native,
video). Tested also nvidia-wmi-ec-backlight, the module does not
even get loaded. Only solution i found is this patchset.


> On Fri, 2024-04-12 at 21:49 +0200, Angelo Dureghello wrote:
>> Add working backlight for "ada lovelace" missing case.
>>
>> The nvif method is actually not working for this chipset so
>> used the drm apis. Also, by dpcd, drm layer is calculating a
>> max brightness of 255, but to get a real correct max brightnes
>> the maximum must be multiplied by a factor of 16.
>>
>> Tested to work properly in Legion Lenovo Pro 5
>>
>> Lenovo Legion 5 Pro 16ARX8
>> Bios ver LPCN49WW
>> 	 LPEC49WW
>> SN PF4T63AZ
>> Nvidia RTX4060 MaxQ/Mobile rev a1 (ADA LOVELACE AD107M)
>> AMD Ryzen 9 7945HX + Radeon
>>
>> and wayland.
>>
>> ---
>> Changes for v2:
>> - add some comments
>> - remove x16 multiplication (hack)
>> - remove forgot debug printk
>>
>> Signed-off-by: Angelo Dureghello <angelo at kernel-space.org>
>> ---
>>   drivers/gpu/drm/nouveau/nouveau_backlight.c | 54
>> +++++++++++++++++++++
>>   1 file changed, 54 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c
>> b/drivers/gpu/drm/nouveau/nouveau_backlight.c
>> index d47442125fa1..7b7306d18ad7 100644
>> --- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
>> +++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
>> @@ -286,6 +286,56 @@ nv50_backlight_init(struct nouveau_backlight
>> *bl,
>>   	return 0;
>>   }
>>   
>> +static int
>> +nv19x_backlight_init(struct nouveau_backlight *bl,
>> +		     struct nouveau_connector *nv_conn,
>> +		     struct nouveau_encoder *nv_encoder,
>> +		     struct backlight_properties *props,
>> +		     const struct backlight_ops **ops)
>> +{
>> +	int ret;
>> +	u16 current_level;
>> +	u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
>> +	u8 current_mode;
>> +	struct nouveau_drm *drm = nouveau_drm(nv_encoder-
>>> base.base.dev);
>> +
>> +	/*
>> +	 * nvif functions, so also nvif_outp_bl_get, are not working
>> with this
>> +	 * connector (return -22), using only drm layer.
>> +	 */
>> +	if (nv_conn->type == DCB_CONNECTOR_eDP) {
>> +
>> +		ret = drm_dp_dpcd_read(&nv_conn->aux,
>> DP_EDP_DPCD_REV, edp_dpcd,
>> +				       EDP_DISPLAY_CTL_CAP_SIZE);
>> +		if (ret < 0)
>> +			return ret;
>> +		if (!drm_edp_backlight_supported(edp_dpcd))
>> +			return -ENODEV;
>> +
>> +		ret = drm_edp_backlight_init(&nv_conn->aux, &bl-
>>> edp_info, 0, edp_dpcd,
>> +					 &current_level,
>> &current_mode);
>> +		if (ret < 0)
>> +			return ret;
>> +
>> +		ret = drm_edp_backlight_enable(&nv_conn->aux, &bl-
>>> edp_info, current_level);
>> +		if (ret < 0) {
>> +			NV_ERROR(drm, "Failed to enable backlight on
>> %s: %d\n",
>> +				 nv_conn->base.name, ret);
>> +			return ret;
>> +		}
>> +
>> +		*ops = &nv50_edp_bl_ops;
>> +
>> +		props->max_brightness = bl->edp_info.max;
>> +		props->brightness = current_level;
>> +		bl->uses_dpcd = true;
>> +
>> +		return 0;
>> +	}
>> +
>> +	return -ENODEV;
>> +}
>> +
>>   int
>>   nouveau_backlight_init(struct drm_connector *connector)
>>   {
>> @@ -332,6 +382,10 @@ nouveau_backlight_init(struct drm_connector
>> *connector)
>>   		ret = nv50_backlight_init(bl,
>> nouveau_connector(connector),
>>   					  nv_encoder, &props, &ops);
>>   		break;
>> +	case NV_DEVICE_INFO_V0_ADA:
>> +		ret = nv19x_backlight_init(bl,
>> nouveau_connector(connector),
>> +					   nv_encoder, &props,
>> &ops);
>> +		break;
>>   	default:
>>   		ret = 0;
>>   		goto fail_alloc;
> Regards,
> angelo