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alistair23-linux/drivers/gpu
Jani Nikula bb83d5fb55 drm/i915/backlight: fix CPU mode backlight takeover on LPT
The pch_get_backlight(), lpt_get_backlight(), and lpt_set_backlight()
functions operate directly on the hardware registers. If inverting the
value is needed, using intel_panel_compute_brightness(), it should only
be done in the interface between hardware registers and
panel->backlight.level.

The CPU mode takeover code added in commit 5b1ec9ac7a
("drm/i915/backlight: Fix backlight takeover on LPT, v3.") reads the
hardware register and converts to panel->backlight.level correctly,
however the value written back should remain in the hardware register
"domain".

This hasn't been an issue, because GM45 machines are the only known
users of i915.invert_brightness and the brightness invert quirk, and
without one of them no conversion is made. It's likely nobody's ever hit
the problem.

Fixes: 5b1ec9ac7a ("drm/i915/backlight: Fix backlight takeover on LPT, v3.")
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: <stable@vger.kernel.org> # v5.1+
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210108152841.6944-1-jani.nikula@intel.com
(cherry picked from commit 0d4ced1c5b)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2021-01-11 12:10:34 +02:00
..
drm drm/i915/backlight: fix CPU mode backlight takeover on LPT 2021-01-11 12:10:34 +02:00
host1x gpu/host1x: bus: Add missing description for 'driver' 2020-11-05 22:12:55 +01:00
ipu-v3 gpu: ipu-v3: remove unused functions 2020-10-26 10:42:38 +01:00
trace
vga pci-v5.11-changes 2020-12-15 16:49:59 -08:00
Makefile