Re: [PATCH v2 2/2] backlight: pwm_bl: Don't rely on a disabled PWM emiting inactive state

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On Fri, 20 Jan 2023, Uwe Kleine-König wrote:

> Most but not all PWMs drive the PWM pin to its inactive state when
> disabled. However if there is no enable_gpio and no regulator the PWM
> must drive the inactive state to actually disable the backlight.
> 
> So keep the PWM on in this case.
> 
> Note that to determine if there is a regulator some effort is required
> because it might happen that there isn't actually one but the regulator
> core gave us a dummy. (A nice side effect is that this makes the
> regulator actually optional even on fully constrained systems.)
> 
> This fixes backlight disabling e.g. on i.MX6 when an inverted PWM is
> used.
> 
> Hint for the future: If this change results in a regression, the bug is
> in the lowlevel PWM driver.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> ---
>  drivers/video/backlight/pwm_bl.c | 30 ++++++++++++++++++++++--------
>  1 file changed, 22 insertions(+), 8 deletions(-)

Applied, thanks

-- 
Lee Jones [李琼斯]



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