On 10/25/19 8:17 PM, Tony Lindgren wrote:
Hi,
- Peter Ujfalusi peter.ujfalusi@ti.com [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
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