[PATCH] drm/amd/display: add panel_power_savings sysfs entry to eDP connectors

[administrator at windeck-gymnasium.de]

I've applied the patch to 6.7.2. The device then shows up under:

/sys/devices/pci0000:00/0000:00:08.1/0000:c1:00.0/drm/card1/card1-eDP-1/amdgpu/panel_power_savings
(on Framework Laptop 13 amd 7840U with 780M).

After a few tests i can say that at least in my system it’s not  
working. Setting a value between 0 and 4 in
/sys/.../panel_power_savings changes nothing in the panel behavior.  
There are no errors in kernel log.

Setting an abmlevel via kernel option still works as intended.

The issue can be resolved if one set the panel_power_savings value and  
after that change the display resolution to a lower value and than  
switch back. For example this script works:

xterm -e 'echo 0 | sudo tee  
/sys/devices/pci0000:00/0000:00:08.1/0000:c1:00.0/drm/card1/card1-eDP-1/amdgpu/panel_power_savings'
gnome-randr modify -m 1920x1200 at 59.999 eDP-1 && gnome-randr modify -m  
2256x1504 at 59.999 eDP-1

> Am 26.01.24 um 23:22 schrieb Hamza Mahfooz:
> We want programs besides the compositor to be able to enable or disable
> panel power saving features. However, since they are currently only
> configurable through DRM properties, that isn't possible. So, to remedy
> that issue introduce a new "panel_power_savings" sysfs attribute.
>
> Cc: Mario Limonciello <mario.limonciello at amd.com>
> Signed-off-by: Hamza Mahfooz <hamza.mahfooz at amd.com>
> ---
> .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 59 +++++++++++++++++++
> 1 file changed, 59 insertions(+)
>
> 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 cd98b3565178..b3fcd833015d 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -6534,6 +6534,58 @@  
> amdgpu_dm_connector_atomic_duplicate_state(struct drm_connector  
> *connector)
> return &new_state->base;
> }
> +static ssize_t panel_power_savings_show(struct device *device,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct drm_connector *connector = dev_get_drvdata(device);
> + struct drm_device *dev = connector->dev;
> + ssize_t val;
> +
> + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> + val = to_dm_connector_state(connector->state)->abm_level;
> + drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +
> + return sysfs_emit(buf, "%lu\n", val);
> +}
> +
> +static ssize_t panel_power_savings_store(struct device *device,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct drm_connector *connector = dev_get_drvdata(device);
> + struct drm_device *dev = connector->dev;
> + long val;
> + int ret;
> +
> + ret = kstrtol(buf, 0, &val);
> +
> + if (ret)
> + return ret;
> +
> + if (val < 0 || val > 4)
> + return -EINVAL;
> +
> + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> + to_dm_connector_state(connector->state)->abm_level = val ?:
> + ABM_LEVEL_IMMEDIATE_DISABLE;
> + drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR_RW(panel_power_savings);
> +
> +static struct attribute *amdgpu_attrs[] = {
> + &dev_attr_panel_power_savings.attr,
> + NULL
> +};
> +
> +static const struct attribute_group amdgpu_group = {
> + .name = "amdgpu",
> + .attrs = amdgpu_attrs
> +};
> +
> static int
> amdgpu_dm_connector_late_register(struct drm_connector *connector)
> {
> @@ -6541,6 +6593,13 @@ amdgpu_dm_connector_late_register(struct  
> drm_connector *connector)
> to_amdgpu_dm_connector(connector);
> int r;
> + if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> + r = sysfs_create_group(&connector->kdev->kobj,
> + &amdgpu_group);
> + if (r)
> + return r;
> + }
> +
> amdgpu_dm_register_backlight_device(amdgpu_dm_connector);
> if ((connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) ||