Messages in this thread | | | Subject | pwm_backlight/general pwm issue. | From | Tony Prisk <> | Date | Sat, 17 Nov 2012 17:07:39 +1300 |
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Hi Thierry,
Looking a little feedback regarding a problem introduced with the pwm patch I sent converting the vt8500 pwm driver to devicetree.
One of the recommendations you made was to enable/disable the pwm clock in pwm_enable/pwm_disable, rather than at driver probe, to reduce power usage. Unfortunately, when the last pwm is disabled, the clock is disabled which prevents the pwm module from responding to register read/writes. This would be fine if pwm_enable was called before any other functions.
The pwm_backlight driver calls pwm_config before pwm_enable, which doesn't work because the pwm module has been disabled. I can appreciate that no one wants to enable a pwm before it's configured so I don't think this is particularly a driver issue.
My recommendation is the re-enable the previous behaviour which was to enable the clock during driver probe, and disable during driver unload.
Looking for your thoughts (or anyone else that wants to chime in).
Regards Tony Prisk
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