Re: [PATCH 2/3] mfd: intel_soc_pmic: Rename pwm_backlight pwm-lookup to pwm_pmic_backlight

Lee Jones
2019-12-10T08:51:22Z

On Tue, 19 Nov 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.
>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> drivers/mfd/intel_soc_pmic_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

For my own reference:
Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>

--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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