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platform/x86: toshiba_acpi: Stop using acpi_video_set_dmi_backlight_type()

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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>
This commit is contained in:
Hans de Goede 2022-06-04 16:18:05 +02:00
parent 4f04c7dc83
commit a2ed70d0ec
2 changed files with 19 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
drivers/acpi/video_detect.c
View File

@ -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

16
drivers/platform/x86/toshiba_acpi.c
View File

@ -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;