On 10/25/19 8:17 PM, Tony Lindgren wrote: > Hi, > > * Peter Ujfalusi <peter.ujfalusi@xxxxxx> [191025 13:05]: >> McPDM module receives it's functional clock from external source. This >> clock is the pdmclk provided by the twl6040 audio IC. If the clock is not >> available all register accesses to McPDM fails and the module is not >> operational. >> >> this has been lurking in my next-wip branch for some time... >> It might not needed anymore as I have not heard about issues with McPDM for a >> while. >> >> It was dropped back then because some core parts were not picked in time and >> this caused some issues, but can not find the exact reason > > Yes it's a strange solution to clock the internal mcpdm module > externally :) Strange is a bit of understatement ;) > AFAIK it's now already handled properly by ti-sysc. We have a common > omap4-mcpdm.dtsi configure mcpdm clock forthe module, then ti-sysc > driver defers probe until the mcpdm clock is available. And for omap5 > we have omap5-board-common.dtsi configure it. I see that the clocks = <&twl6040>; clock-names = "pdmclk"; are added to the mcpdm node (some patch from me, some new). But the McPDM driver itself never requests this clock w/o this patch. > So probably the only thing omap-mcpdm.c driver needs to do is to > call PM runtime functions, maybe it's already doing that. Yes, it has support for pm_runtime. Looking at ti-sci I think I know why it works. ti-sci will get the 'pdmclk' as a clock for the device and going to manage it because the SYSC_QUIRK_EXT_OPT_CLOCK is set for McPDM. So pm_runtime is going to handle the clock coming from twl6040. And now I remember to test these ti-sci changes :o I wonder why I have not dropped this patch back then from my wip branch. Let's just ignore this patch. - Peter Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
