On 13/10/2023 14:25, Andreas Kemnade wrote: >> I guess it is because of the pm_runtime_put_sync() in the >> omap2_mcbsp_set_clks_src() around the fclk re-parenting. >> That is a bit dubious thing for sure. We need to disable the device to >> be able to re-parent the fclk but if we disable the device it is going >> to be powered down, right? I think we have appropriate context handling, >> so it might work, but it is certainly not a rock solid code... If you >> have a stream running already, you don't really want to kill the McBSP. >> > Ok, so if the device is powered of at omap2_mcbsp_set_clks_src() > we get the usage count underflow, and the counter is incremented > immediately again in the runtime put function. So things get out of balance... > I'll check Tony's fix here. > >> The problem is that this mux is outside of the McBSP IP, so we need a >> system level (iow, clk API) way to change it runtime. >> >> What is the machine driver where this happens? If you set the sysclk in >> hw_params of the machine driver, it will be OK, but if you do that in >> probe time then it is likely going to fail as you experienced >> > As you see in the other patches of this series, > it is a simple-audio-card with a tlv320aic3x codec > in combination with the mcbsp. To be honest I would be happier if we can just remove the whole omap2_mcbsp_set_clks_src() and leave the CLKS source selection outside of the driver. But omap3pandora is selecting external clock as parent (OMAP_MCBSP_SYSCLK_CLKS_EXT - in hw_params, so it actually works) and I don't know what happens if this functionality is removed. Likely going to break Pandora. That is fixable, but what worries me is this comment and code: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/soc/ti/omap-mcbsp.c#n388 Which is added by me a long time ago: e386615c01d37 ("ASoC: omap-mcbsp: When closing the port select PRCM source for CLKS signal") I'm not sure if this is possible to do in any other way. -- Péter
