On Mon, 16 Dec 2019, Hans de Goede wrote: > At least Bay Trail (BYT) and Cherry Trail (CHT) devices can use 1 of 2 > different PWM controllers for controlling the LCD's backlight brightness. > > Either the one integrated into the PMIC or the one integrated into the > SoC (the 1st LPSS PWM controller). > > So far in the LPSS code on BYT we have skipped registering the LPSS PWM > controller "pwm_backlight" lookup entry when a Crystal Cove PMIC is > present, assuming that in this case the PMIC PWM controller will be used. > > On CHT we have been relying on only 1 of the 2 PWM controllers being > enabled in the DSDT at the same time; and always registered the lookup. > > So far this has been working, but the correct way to determine which PWM > controller needs to be used is by checking a bit in the VBT table and > recently I've learned about 2 different BYT devices: > Point of View MOBII TAB-P800W > Acer Switch 10 SW5-012 > > Which use a Crystal Cove PMIC, yet the LCD is connected to the SoC/LPSS > PWM controller (and the VBT correctly indicates this), so here our old > heuristics fail. > > Since only the i915 driver has access to the VBT, this commit renames > the "pwm_backlight" lookup entries for the Crystal Cove PMIC's PWM > controller to "pwm_pmic_backlight" so that the i915 driver can do a > pwm_get() for the right controller depending on the VBT bit, instead of > the i915 driver relying on a "pwm_backlight" lookup getting registered > which magically points to the right controller. > > Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > --- > drivers/mfd/intel_soc_pmic_core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Acked-by: Lee Jones <lee.jones@xxxxxxxxxx> -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
