From 52304886ea49ee662589aff05925ef226c17a6a6 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Thu, 26 Oct 2023 15:53:03 +0200 Subject: ACPI: video: Add comment about acpi_video_backlight_use_native() usage Add a comment explaining that acpi_video_backlight_use_native() MUST only be used by GPU drivers and that it must NOT be used on other places. Signed-off-by: Hans de Goede Signed-off-by: Rafael J. Wysocki --- include/acpi/video.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/include/acpi/video.h b/include/acpi/video.h index 4230392b5b0b..3d538d4178ab 100644 --- a/include/acpi/video.h +++ b/include/acpi/video.h @@ -75,6 +75,15 @@ static inline enum acpi_backlight_type acpi_video_get_backlight_type(void) return __acpi_video_get_backlight_type(false, NULL); } +/* + * This function MUST only be called by GPU drivers to check if the driver + * should register a backlight class device. This function not only checks + * if a GPU native backlight device should be registered it *also* tells + * the ACPI video-detect code that native GPU backlight control is available. + * Therefor calling this from any place other then the GPU driver is wrong! + * To check if GPU native backlight control is used in other places instead use: + * if (acpi_video_get_backlight_type() == acpi_backlight_native) { ... } + */ static inline bool acpi_video_backlight_use_native(void) { return __acpi_video_get_backlight_type(true, NULL) == acpi_backlight_native; -- cgit From c7add369b4cc599db336ca67578a052c5b0f0891 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Wed, 15 Nov 2023 18:48:11 +0100 Subject: ACPI: video: Drop should_check_lcd_flag() Since commit 3dbc80a3e4c5 ("ACPI: video: Make backlight class device registration a separate step (v2)") acpi_video# backlights are no longer automatically registered. Instead they now only get registered when the GPU/KMS driver calls acpi_video_register_backlight() which it only does when it has detected an internal LCD panel. This fixes the issue of sometimes a non-working acpi_video# backlight showing up on Desktops / HDMI-sticks without an internal LCD display in a more complete and robust manner then the LCD flag check which gets enabled by the should_check_lcd_flag() helper does. Therefor the should_check_lcd_flag() helper is no longer necessary. The lcd_only flag itself is still necessary to only register a single backlight device (for the right output) on the ESPRIMO Mobile M9410 which has 2 ACPI video connector nodes with a _BCM control method, which is the issue for which the flag was originally introduced in commit e50b9be14ab0 ("ACPI / video: only register backlight for LCD device"). Signed-off-by: Hans de Goede Signed-off-by: Rafael J. Wysocki --- drivers/acpi/acpi_video.c | 56 +---------------------------------------------- 1 file changed, 1 insertion(+), 55 deletions(-) diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index d321ca7160d9..5eded14f8853 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -67,7 +67,7 @@ MODULE_PARM_DESC(hw_changes_brightness, static bool device_id_scheme = false; module_param(device_id_scheme, bool, 0444); -static int only_lcd = -1; +static int only_lcd; module_param(only_lcd, int, 0444); static bool may_report_brightness_keys; @@ -2141,57 +2141,6 @@ static int __init intel_opregion_present(void) return opregion; } -/* Check if the chassis-type indicates there is no builtin LCD panel */ -static bool dmi_is_desktop(void) -{ - const char *chassis_type; - unsigned long type; - - chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE); - if (!chassis_type) - return false; - - if (kstrtoul(chassis_type, 10, &type) != 0) - return false; - - switch (type) { - case 0x03: /* Desktop */ - case 0x04: /* Low Profile Desktop */ - case 0x05: /* Pizza Box */ - case 0x06: /* Mini Tower */ - case 0x07: /* Tower */ - case 0x10: /* Lunch Box */ - case 0x11: /* Main Server Chassis */ - return true; - } - - return false; -} - -/* - * We're seeing a lot of bogus backlight interfaces on newer machines - * without a LCD such as desktops, servers and HDMI sticks. Checking the - * lcd flag fixes this, enable this by default on any machines which are: - * 1. Win8 ready (where we also prefer the native backlight driver, so - * normally the acpi_video code should not register there anyways); *and* - * 2.1 Report a desktop/server DMI chassis-type, or - * 2.2 Are an ACPI-reduced-hardware platform (and thus won't use the EC for - backlight control) - */ -static bool should_check_lcd_flag(void) -{ - if (!acpi_osi_is_win8()) - return false; - - if (dmi_is_desktop()) - return true; - - if (acpi_reduced_hardware()) - return true; - - return false; -} - int acpi_video_register(void) { int ret = 0; @@ -2205,9 +2154,6 @@ int acpi_video_register(void) goto leave; } - if (only_lcd == -1) - only_lcd = should_check_lcd_flag(); - dmi_check_system(video_dmi_table); ret = acpi_bus_register_driver(&acpi_video_bus); -- cgit From ccd45faf4973746c4f30ea41eec864e5cf191099 Mon Sep 17 00:00:00 2001 From: Nikita Kiryushin Date: Thu, 9 Nov 2023 16:49:25 +0300 Subject: ACPI: video: check for error while searching for backlight device parent If acpi_get_parent() called in acpi_video_dev_register_backlight() fails, for example, because acpi_ut_acquire_mutex() fails inside acpi_get_parent), this can lead to incorrect (uninitialized) acpi_parent handle being passed to acpi_get_pci_dev() for detecting the parent pci device. Check acpi_get_parent() result and set parent device only in case of success. Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: 9661e92c10a9 ("acpi: tie ACPI backlight devices to PCI devices if possible") Signed-off-by: Nikita Kiryushin Signed-off-by: Rafael J. Wysocki --- drivers/acpi/acpi_video.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index 5eded14f8853..f71287072719 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -1717,12 +1717,12 @@ static void acpi_video_dev_register_backlight(struct acpi_video_device *device) return; count++; - acpi_get_parent(device->dev->handle, &acpi_parent); - - pdev = acpi_get_pci_dev(acpi_parent); - if (pdev) { - parent = &pdev->dev; - pci_dev_put(pdev); + if (ACPI_SUCCESS(acpi_get_parent(device->dev->handle, &acpi_parent))) { + pdev = acpi_get_pci_dev(acpi_parent); + if (pdev) { + parent = &pdev->dev; + pci_dev_put(pdev); + } } memset(&props, 0, sizeof(struct backlight_properties)); -- cgit