Messages in this thread | | | Date | Thu, 13 Oct 2022 13:59:07 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH AUTOSEL 4.19 06/10] ACPI: video: Change disable_backlight_sysfs_if quirks to acpi_backlight=native |
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On Mon, Oct 10, 2022 at 09:36:53AM +0200, Hans de Goede wrote: >Hi, > >On 10/10/22 01:57, Sasha Levin wrote: >> From: Hans de Goede <hdegoede@redhat.com> >> >> [ Upstream commit c5b94f5b7819348c59f9949b2b75c341a114cdd4 ] >> >> Some Toshibas have a broken acpi-video interface for brightness control >> and need a special firmware call on resume to turn the panel back on. >> So far these have been using the disable_backlight_sysfs_if workaround >> to deal with this. >> >> The recent x86/acpi backlight refactoring has broken this workaround: >> 1. This workaround relies on acpi_video_get_backlight_type() returning >> acpi_video so that the acpi_video code actually runs; and >> 2. this relies on the actual native GPU driver to offer the sysfs >> backlight interface to userspace. >> >> After the refactor this breaks since the native driver will no >> longer register its backlight-device if acpi_video_get_backlight_type() >> does not return native and making it return native breaks 1. >> >> Keeping the acpi_video backlight handling on resume active, while not >> using it to set the brightness, is necessary because it does a _BCM >> call on resume which is necessary to turn the panel back on on resume. >> >> Looking at the DSDT shows that this _BCM call results in a Toshiba >> HCI_SET HCI_LCD_BRIGHTNESS call, which turns the panel back on. >> >> This kind of special vendor specific handling really belongs in >> the vendor specific acpi driver. An earlier patch in this series >> modifies toshiba_acpi to make the necessary HCI_SET call on resume >> on affected models. >> >> With toshiba_acpi taking care of the HCI_SET call on resume, >> the acpi_video code no longer needs to call _BCM on resume. >> >> So instead of using the (now broken) disable_backlight_sysfs_if >> workaround, simply setting acpi_backlight=native to disable >> the broken apci-video interface is sufficient fix things now. >> >> After this there are no more users of the disable_backlight_sysfs_if >> flag and as discussed above the flag also no longer works as intended, >> so remove the disable_backlight_sysfs_if flag entirely. >> >> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >> Tested-by: Arvid Norlander <lkml@vorpal.se> >> Signed-off-by: Hans de Goede <hdegoede@redhat.com> >> Signed-off-by: Sasha Levin <sashal@kernel.org> > >This patch goes hand in hand with: > >commit 3cb1f40dfdc3 ("drivers/platform: toshiba_acpi: Call HCI_PANEL_POWER_ON on resume on some models") > >and without that commit also being present it will cause a regression on >the quirked Toshiba models. > >This really is part of the big x86/ACPI backlight handling refactor which >has landed in 6.1 and as such is not intended for older kernels, please >drop this from the stable series.
Will do, thanks!
-- Thanks, Sasha
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