Dne 20.8.2015 v 22:01 Robert Jarzmik napsal(a):
> Petr Cvek <[email protected]> writes:
>
>> Add support for alternative LCD backlight with GPIO (no brightness).
> Here, I don't understand, the commit message is too short.
>
> Are there 2 brightness controls on magician, or are these 2 different
> magicians
> (hardware wise), each having a different backlight control ? Or is it there
> is a
> GPIO to light up the screen and a PWM backlight ?
>
> I have to understand first.
>
I have aimed for a configuration, where user can use PWM xor GPIO backlight. As
pin mux can set GPIO or PWM (or UART :-D) on PWM pin, you can choose if you
spare few kB (as magician has only 64MB RAM and 64MB flash) on GPIO or will
have smooth backlight with PWM.
I have tested both (I think I have added the gpio backlight for debugging a
regression in pwm_bl).
Only ugly thing is the GPIO definition:
#if IS_ENABLED(CONFIG_PWM_PXA)
/* PWM 0 - LCD backlight */
GPIO16_PWM0_OUT,
#else
/* Ensure static backlight without any driver */
MFP_CFG_OUT(GPIO16, AF0, DRIVE_LOW), /* Backlight enabled */
#endif
Hmmm.. I think I can do this better in pwm-backlight init/exit (same way as
pxa_ficp). During init the pin mux will switch to Alternate Function (PWM) and
during exit it will switch to GPIO (which can be used by gpio-backlight). This
will remove ugly ifdef.
Best regards,
Petr
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