[U-Boot] [PATCH v2] sunxi: display: Use PWM to drive backlight where applicable

[Simon Glass]

Hi Hans,

On 26 August 2016 at 08:21, Hans de Goede <hdegoede at redhat.com> wrote:
> Hi,
>
>
> On 26-08-16 16:15, Peter Korsgaard wrote:
>>>>>>>
>>>>>>> "Hans" == Hans de Goede <hdegoede at redhat.com> writes:
>>
>>
>>  > When the backlight's pwm input is connected to a pwm output of the SoC,
>>  > actually use pwm to drive the backlight.
>>
>>  > The mean reason for doing this is to fix the backlight turning off
>>  > for aprox. 1 second while the kernel is booting. This is caused by
>>  > the kernel actually using pwm to drive the backlight, so that it
>>  > can dim the backlight. First the pwm driver loads and switches the
>>  > pinmux for the pin driving the backlight's pwm input to the pwm
>>  > controller. Then about 1s later the actual backlight driver loads
>>  > and tells the pwm driver to actually update the pwm settings, which
>>  > have a power-on-reset value of "off".
>>
>>  > An additional advantage is that this allows us to initatiate the
>>  > backlight at 80%, which is the kernel default, avoiding a brightness
>>  > change while the kernel loads.
>>
>>  > +++ b/drivers/video/sunxi_display.c
>>  > @@ -12,6 +12,7 @@
>>  >  #include <asm/arch/clock.h>
>>  >  #include <asm/arch/display.h>
>>  >  #include <asm/arch/gpio.h>
>>  > +#include <asm/arch/pwm.h>
>>  >  #include <asm/global_data.h>
>>  >  #include <asm/gpio.h>
>>  >  #include <asm/io.h>
>>  > @@ -34,7 +35,6 @@
>>  >  #define PWM_ON 1
>>  >  #define PWM_OFF 0
>>  >  #endif
>>  > -
>>
>> Unrelated white space change. Other than that:
>
>
> Oops, fixed locally.
>
>> Reviewed by: Peter Korsgaard <peter at korsgaard.com>
>
>
> Thank you.

Can this move to driver model for the PWM, and for the display for that matter?

>
> Regards,
>
> Hans
>
>
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Regards,
Simon