On Friday, April 20, 2018 3:31:30 PM CEST Andy Shevchenko wrote: > On Fri, 2018-04-13 at 14:54 +0200, Hans de Goede wrote: > > 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. > > > > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Applied, thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
