drm: panel-backlight-quirks: Convert brightness quirk to generic structure

Currently, the brightness quirk is limited to minimum brightness only.
Refactor it to a structure, so that more quirks can be added in the
future. Reserve 0 value for "no quirk", and use u16 to allow minimum
brightness up to 255.

Tested-by: Philip Müller <philm@manjaro.org>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
Link: https://lore.kernel.org/r/20250829145541.512671-3-lkml@antheas.dev
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>

Author: antheas

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -3612,11 +3612,11 @@ static struct drm_mode_config_helper_funcs amdgpu_dm_mode_config_helperfuncs = {
 
 static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 {
+	const struct drm_panel_backlight_quirk *panel_backlight_quirk;
 	struct amdgpu_dm_backlight_caps *caps;
 	struct drm_connector *conn_base;
 	struct amdgpu_device *adev;
 	struct drm_luminance_range_info *luminance_range;
-	int min_input_signal_override;
 
 	if (aconnector->bl_idx == -1 ||
 	    aconnector->dc_link->connector_signal != SIGNAL_TYPE_EDP)
@@ -3656,9 +3656,13 @@ static void update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 	else
 		caps->aux_min_input_signal = 1;
 
-	min_input_signal_override = drm_get_panel_min_brightness_quirk(aconnector->drm_edid);
-	if (min_input_signal_override >= 0)
-		caps->min_input_signal = min_input_signal_override;
+	panel_backlight_quirk =
+		drm_get_panel_backlight_quirk(aconnector->drm_edid);
+	if (!IS_ERR_OR_NULL(panel_backlight_quirk)) {
+		if (panel_backlight_quirk->min_brightness)
+			caps->min_input_signal =
+				panel_backlight_quirk->min_brightness - 1;
+	}
 }
 
 DEFINE_FREE(sink_release, struct dc_sink *, if (_T) dc_sink_release(_T))

drivers/gpu/drm/drm_panel_backlight_quirks.c

@@ -8,44 +8,45 @@
 #include <drm/drm_edid.h>
 #include <drm/drm_utils.h>
 
-struct drm_panel_min_backlight_quirk {
+struct drm_get_panel_backlight_quirk {
 	struct {
 		enum dmi_field field;
 		const char * const value;
 	} dmi_match;
 	struct drm_edid_ident ident;
-	u8 min_brightness;
+	struct drm_panel_backlight_quirk quirk;
 };
 
-static const struct drm_panel_min_backlight_quirk drm_panel_min_backlight_quirks[] = {
+static const struct drm_get_panel_backlight_quirk drm_panel_min_backlight_quirks[] = {
 	/* 13 inch matte panel */
 	{
 		.dmi_match.field = DMI_BOARD_VENDOR,
 		.dmi_match.value = "Framework",
 		.ident.panel_id = drm_edid_encode_panel_id('B', 'O', 'E', 0x0bca),
 		.ident.name = "NE135FBM-N41",
-		.min_brightness = 0,
+		.quirk = { .min_brightness = 1, },
 	},
 	/* 13 inch glossy panel */
 	{
 		.dmi_match.field = DMI_BOARD_VENDOR,
 		.dmi_match.value = "Framework",
 		.ident.panel_id = drm_edid_encode_panel_id('B', 'O', 'E', 0x095f),
 		.ident.name = "NE135FBM-N41",
-		.min_brightness = 0,
+		.quirk = { .min_brightness = 1, },
 	},
 	/* 13 inch 2.8k panel */
 	{
 		.dmi_match.field = DMI_BOARD_VENDOR,
 		.dmi_match.value = "Framework",
 		.ident.panel_id = drm_edid_encode_panel_id('B', 'O', 'E', 0x0cb4),
 		.ident.name = "NE135A1M-NY1",
-		.min_brightness = 0,
+		.quirk = { .min_brightness = 1, },
 	},
 };
 
-static bool drm_panel_min_backlight_quirk_matches(const struct drm_panel_min_backlight_quirk *quirk,
-						  const struct drm_edid *edid)
+static bool drm_panel_min_backlight_quirk_matches(
+	const struct drm_get_panel_backlight_quirk *quirk,
+	const struct drm_edid *edid)
 {
 	if (!dmi_match(quirk->dmi_match.field, quirk->dmi_match.value))
 		return false;
@@ -57,39 +58,39 @@ static bool drm_panel_min_backlight_quirk_matches(const struct drm_panel_min_bac
 }
 
 /**
- * drm_get_panel_min_brightness_quirk - Get minimum supported brightness level for a panel.
+ * drm_get_panel_backlight_quirk - Get backlight quirks for a panel
  * @edid: EDID of the panel to check
  *
  * This function checks for platform specific (e.g. DMI based) quirks
  * providing info on the minimum backlight brightness for systems where this
- * cannot be probed correctly from the hard-/firm-ware.
+ * cannot be probed correctly from the hard-/firm-ware and other sources.
  *
  * Returns:
- * A negative error value or
- * an override value in the range [0, 255] representing 0-100% to be scaled to
- * the drivers target range.
+ * a drm_panel_backlight_quirk struct if a quirk was found, otherwise an
+ * error pointer.
  */
-int drm_get_panel_min_brightness_quirk(const struct drm_edid *edid)
+const struct drm_panel_backlight_quirk *
+drm_get_panel_backlight_quirk(const struct drm_edid *edid)
 {
-	const struct drm_panel_min_backlight_quirk *quirk;
+	const struct drm_get_panel_backlight_quirk *quirk;
 	size_t i;
 
 	if (!IS_ENABLED(CONFIG_DMI))
-		return -ENODATA;
+		return ERR_PTR(-ENODATA);
 
 	if (!edid)
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 
 	for (i = 0; i < ARRAY_SIZE(drm_panel_min_backlight_quirks); i++) {
 		quirk = &drm_panel_min_backlight_quirks[i];
 
 		if (drm_panel_min_backlight_quirk_matches(quirk, edid))
-			return quirk->min_brightness;
+			return &quirk->quirk;
 	}
 
-	return -ENODATA;
+	return ERR_PTR(-ENODATA);
 }
-EXPORT_SYMBOL(drm_get_panel_min_brightness_quirk);
+EXPORT_SYMBOL(drm_get_panel_backlight_quirk);
 
 MODULE_DESCRIPTION("Quirks for panel backlight overrides");
 MODULE_LICENSE("GPL");

include/drm/drm_utils.h

@@ -16,7 +16,12 @@ struct drm_edid;
 
 int drm_get_panel_orientation_quirk(int width, int height);
 
-int drm_get_panel_min_brightness_quirk(const struct drm_edid *edid);
+struct drm_panel_backlight_quirk {
+	u16 min_brightness;
+};
+
+const struct drm_panel_backlight_quirk *
+drm_get_panel_backlight_quirk(const struct drm_edid *edid);
 
 signed long drm_timeout_abs_to_jiffies(int64_t timeout_nsec);