Hi,
On 6/12/20 12:20 AM, Uwe Kleine-König wrote:
On Sun, Jun 07, 2020 at 08:18:34PM +0200, Hans de Goede wrote:
The pwm-crc code is using 2 different enable bits:
1. bit 7 of the PWM0_CLK_DIV (PWM_OUTPUT_ENABLE)
2. bit 0 of the BACKLIGHT_EN register
So far we've kept the PWM_OUTPUT_ENABLE bit set when disabling the PWM,
this commit makes crc_pwm_disable() clear it on disable and makes
crc_pwm_enable() set it again on re-enable.
This should disable the internal (divided) PWM clock and tri-state the
PWM output pin when disabled, saving some power.
It would be great if you could also document that disabling the PWM
makes the output tri-state. There are a few drivers that have a
"Limitations" section at their top. Describing that there (in the same
format) would be the right place.
Also note that according to Thierry's conception getting a (driven)
inactive output is the right thing for a disabled PWM.
Hmm, the tri-state thing is an assumption from my side and we
don't have any docs for this PWM controller, so I'm not sure at
all if that is true. So I think it will be better to just drop
the tri-state bit from the commit msg for the next version.
Regards,
Hans
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