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[ Upstream commit c975e472ec12392a0c34de1350e634310f8a1dea ] The Point of View mobii wintab p800w Bay Trail tablet comes with a Crystal Cove PMIC, yet uses the LPSS PWM for backlight control, rather then the Crystal Cove's PWM, so we need to call pwm_add_table() to add a pwm_backlight mapping for the LPSS pwm despite there being an INT33FD ACPI device present. On all Bay Trail devices the _HRV object of the INT33FD ACPI device will normally return 2, to indicate the Bay Trail variant of the CRC PMIC is present, except on this tablet where _HRV is 0xffff. I guess this is a hack to make the windows Crystal Cove PWM driver not bind. Out of the 44 DSTDs with an INT33FD device in there which I have (from different model devices) only the pov mobii wintab p800w uses 0xffff for the HRV. The byt_pwm_setup code calls acpi_dev_present to check for the presence of a INT33FD ACPI device which indicates that a CRC PMIC is present and if the INT33FD ACPI device is present then byt_pwm_setup will not add a pwm_backlight mapping for the LPSS pwm, so that the CRC PWM will get used instead. acpi_dev_present has a hrv parameter, this commit make us pass 2 instead of -1, so that things still match on normal tablets, but on this special case with its _HRV of 0xffff, the check will now fail so that the pwm_backlight mapping for the LPSS pwm gets added fixing backlight brightness control on this device. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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