[PATCH v4 21/31] platform/x86: toshiba_acpi: Stop using acpi_video_set_dmi_backlight_type()

Hans de Goede
2022-08-24T12:17:47Z

acpi_video_set_dmi_backlight_type() is troublesome because it may end up
getting called after other backlight drivers have already called
acpi_video_get_backlight_type() resulting in the other drivers
already being registered even though they should not.

In case of the acpi_video backlight, acpi_video_set_dmi_backlight_type()
actually calls acpi_video_unregister_backlight() since that is often
probed earlier, leading to userspace seeing the acpi_video0 class
device being briefly available, leading to races in userspace where
udev probe-rules try to access the device and it is already gone.

In case of toshiba_acpi there are no DMI quirks to move to
acpi/video_detect.c, but it also (ab)uses it for transflective
displays. Adding transflective display support to video_detect.c would
be quite involved. But luckily there are only 2 known models with
a transflective display, so we can just add DMI quirks for those.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/acpi/video_detect.c | 19 +++++++++++++++++++
drivers/platform/x86/toshiba_acpi.c | 16 ----------------
2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index be2fc43418af..74e2087c8ff0 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -190,6 +190,25 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
},
},

+ /*
+ * Toshiba models with Transflective display, these need to use
+ * the toshiba_acpi vendor driver for proper Transflective handling.
+ */
+ {
+ .callback = video_detect_force_vendor,
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R500"),
+ },
+ },
+ {
+ .callback = video_detect_force_vendor,
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R600"),
+ },
+ },
+
/*
* These models have a working acpi_video backlight control, and using
* native backlight causes a regression where backlight does not work
diff --git a/drivers/platform/x86/toshiba_acpi.c b/drivers/platform/x86/toshiba_acpi.c
index 0fc9e8b8827b..030dc37d50b8 100644
--- a/drivers/platform/x86/toshiba_acpi.c
+++ b/drivers/platform/x86/toshiba_acpi.c
@@ -271,14 +271,6 @@ static const struct key_entry toshiba_acpi_alt_keymap[] = {
{ KE_END, 0 },
};

-/*
- * List of models which have a broken acpi-video backlight interface and thus
- * need to use the toshiba (vendor) interface instead.
- */
-static const struct dmi_system_id toshiba_vendor_backlight_dmi[] = {
- {}
-};
-
/*
* Utility
*/
@@ -2881,14 +2873,6 @@ static int toshiba_acpi_setup_backlight(struct toshiba_acpi_dev *dev)
return 0;
}

- /*
- * Tell acpi-video-detect code to prefer vendor backlight on all
- * systems with transflective backlight and on dmi matched systems.
- */
- if (dev->tr_backlight_supported ||
- dmi_check_system(toshiba_vendor_backlight_dmi))
- acpi_video_set_dmi_backlight_type(acpi_backlight_vendor);
-
if (acpi_video_get_backlight_type() != acpi_backlight_vendor)
return 0;

--
2.37.2