[PATCH] OMAP4: clockdomain: Follow recommended enable sequence

Rajendra Nayak rnayak at ti.com
Fri Apr 1 11:40:40 EDT 2011

On 4/1/2011 8:21 PM, Rajendra Nayak wrote:
> Hi Paul,
> <snip>..
>>> In omap_hwmod.c:_enable(), what do you think about:
>>> 1. saving the current idle mode of the clockdomain,
>>> 2. forcing the clockdomain to software-supervised wakeup.
>>> 3. enabling clocks and waiting for the module as we currently do, then
>>> 4. switching the clockdomain's idle mode back to its original state?
>>> Seems like that would be a reasonable approach for the short term, at
>>> least for drivers that have been converted to PM runtime.
>> Ok, I'll try and get some RFC patches in these lines soon.
> I tried some of what you were suggesting here and it seems to
> work well, like you said, for the drivers which are converted
> to PM runtime.
> Now the issue seems to be, how do we handle the ones which
> are *still* using clock framework to enable main clocks and
> are yet to be converted to PM runtime.
> One such, MMC, is showing me issues on OMAP4 even at boot
> and causes a crash.
> Its a different thing that some of these drivers which use
> direct clock calls are working by fluke on OMAP4 since the
> clock framework does not even wait for the modules to become
> accessible after the clock enable.
> I know the right way seems to be to get all these drivers
> converted to PM runtime, but that might take sometime.

One way I am able to get this working (atleast MMC)
is by preventing the clock domain belonging to MMC module
from being programmed into HW_SUP mode.
Acceptable hack in the interim while we wait for the MMC
driver to be using PM runtime?

> regards,
> Rajendra

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