From: Thomas Weißschuh linux@weissschuh.net
[ Upstream commit 22e5c7ae12145af13785e3ff138395d5b1a22116 ]
Panels using a PWM-controlled backlight source do not have a standard way to communicate their valid PWM ranges. On x86 the ranges are read from ACPI through driver-specific tables. The built-in ranges are not necessarily correct, or may grow stale if an older device can be retrofitted with newer panels.
Add a quirk infrastructure with which the minimum valid backlight value can be maintained as part of the kernel.
Signed-off-by: Thomas Weißschuh linux@weissschuh.net Tested-by: Dustin L. Howett dustin@howett.net Reviewed-by: Mario Limonciello mario.limonciello@amd.com Reviewed-by: Harry Wentland harry.wentland@amd.com Signed-off-by: Mario Limonciello mario.limonciello@amd.com Link: https://patchwork.freedesktop.org/patch/msgid/20241111-amdgpu-min-backlight-... Signed-off-by: Sasha Levin sashal@kernel.org --- Documentation/gpu/drm-kms-helpers.rst | 3 + drivers/gpu/drm/Kconfig | 4 ++ drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_panel_backlight_quirks.c | 70 ++++++++++++++++++++ include/drm/drm_utils.h | 4 ++ 5 files changed, 82 insertions(+) create mode 100644 drivers/gpu/drm/drm_panel_backlight_quirks.c
diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst index 8cf2f041af470..b4ee25af1702b 100644 --- a/Documentation/gpu/drm-kms-helpers.rst +++ b/Documentation/gpu/drm-kms-helpers.rst @@ -221,6 +221,9 @@ Panel Helper Reference .. kernel-doc:: drivers/gpu/drm/drm_panel_orientation_quirks.c :export:
+.. kernel-doc:: drivers/gpu/drm/drm_panel_backlight_quirks.c + :export: + Panel Self Refresh Helper Reference ===================================
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index 772fc7625639d..b55be8889e2ca 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -530,6 +530,10 @@ config DRM_HYPERV config DRM_EXPORT_FOR_TESTS bool
+# Separate option as not all DRM drivers use it +config DRM_PANEL_BACKLIGHT_QUIRKS + tristate + config DRM_LIB_RANDOM bool default n diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index 463afad1b5ca6..06b73068d2483 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -95,6 +95,7 @@ drm-$(CONFIG_DRM_PANIC_SCREEN_QR_CODE) += drm_panic_qr.o obj-$(CONFIG_DRM) += drm.o
obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o +obj-$(CONFIG_DRM_PANEL_BACKLIGHT_QUIRKS) += drm_panel_backlight_quirks.o
# # Memory-management helpers diff --git a/drivers/gpu/drm/drm_panel_backlight_quirks.c b/drivers/gpu/drm/drm_panel_backlight_quirks.c new file mode 100644 index 0000000000000..6b8bbed77c7f1 --- /dev/null +++ b/drivers/gpu/drm/drm_panel_backlight_quirks.c @@ -0,0 +1,70 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/array_size.h> +#include <linux/dmi.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <drm/drm_edid.h> +#include <drm/drm_utils.h> + +struct drm_panel_min_backlight_quirk { + struct { + enum dmi_field field; + const char * const value; + } dmi_match; + struct drm_edid_ident ident; + u8 min_brightness; +}; + +static const struct drm_panel_min_backlight_quirk drm_panel_min_backlight_quirks[] = { +}; + +static bool drm_panel_min_backlight_quirk_matches(const struct drm_panel_min_backlight_quirk *quirk, + const struct drm_edid *edid) +{ + if (!dmi_match(quirk->dmi_match.field, quirk->dmi_match.value)) + return false; + + if (!drm_edid_match(edid, &quirk->ident)) + return false; + + return true; +} + +/** + * drm_get_panel_min_brightness_quirk - Get minimum supported brightness level 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. + * + * 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. + */ +int drm_get_panel_min_brightness_quirk(const struct drm_edid *edid) +{ + const struct drm_panel_min_backlight_quirk *quirk; + size_t i; + + if (!IS_ENABLED(CONFIG_DMI)) + return -ENODATA; + + if (!edid) + return -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 -ENODATA; +} +EXPORT_SYMBOL(drm_get_panel_min_brightness_quirk); + +MODULE_DESCRIPTION("Quirks for panel backlight overrides"); +MODULE_LICENSE("GPL"); diff --git a/include/drm/drm_utils.h b/include/drm/drm_utils.h index 70775748d243b..15fa9b6865f44 100644 --- a/include/drm/drm_utils.h +++ b/include/drm/drm_utils.h @@ -12,8 +12,12 @@
#include <linux/types.h>
+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); + signed long drm_timeout_abs_to_jiffies(int64_t timeout_nsec);
#endif