[lkml]   [2019]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [CI 2/3] mfd: intel_soc_pmic: Rename pwm_backlight pwm-lookup to pwm_pmic_backlight
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 <>
> Reviewed-by: Andy Shevchenko <>
> Signed-off-by: Hans de Goede <>
> ---
> drivers/mfd/intel_soc_pmic_core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Lee Jones <>

Lee Jones [李琼斯]
Linaro Services Technical Lead │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

 \ /
  Last update: 2019-12-17 09:04    [W:3.505 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site