Hi all, For the last few days I've been debugging a lot to get pwm working again since recent changes in 5.6-rc1 broke it for me.
Testing shows the pwm controller crashes (or the output gets stuck) when the period register is written when the channel is disabled while the clock gate is still on. Usually after multiple writes, but one write can also lead to unpredictable behaviour. Patch 3 and 4 fix this. Patch 2 contains a fix which wouldn't completely turn off the pwm if the output is disabled. The clock gate needs to stay on for at least one more period to ensure the output is properly disabled. This issue has been around for a long time but has probably stayed unnoticed because if the duty_cycle is also changed to 0, you can't tell the difference. Patch 1 removes some leftovers which aren't needed anymore. Obviously these patches work for my device, but I'd like to hear your opinion if any of these changes make sense. After days, this one is a bit blurry for me. Thanks to Uwe for some help with debugging. Pascal. Pascal Roeleven (4): pwm: sun4i: Remove redundant needs_delay pwm: sun4i: Disable pwm before turning off clock gate pwm: sun4i: Move delay to function pwm: sun4i: Delay after writing the period drivers/pwm/pwm-sun4i.c | 53 ++++++++++++++++++++--------------------- 1 file changed, 26 insertions(+), 27 deletions(-) -- 2.20.1 -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/20200317155906.31288-1-dev%40pascalroeleven.nl.
