Commit a2ed70d0 authored by Hans de Goede's avatar Hans de Goede
Browse files

platform/x86: toshiba_acpi: Stop using acpi_video_set_dmi_backlight_type() 



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: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
parent 4f04c7dc

drivers/acpi/video_detect.c

+19 −0
Original line number Diff line number Diff line
@@ -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

drivers/platform/x86/toshiba_acpi.c

+0 −16
Original line number Diff line number Diff line
@@ -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;