andy git 06/15 suspend/resume observations

Andy Green andy at
Mon Jun 16 10:20:15 CEST 2008

Hash: SHA1

Somebody in the thread at some point said:
| On Sun, Jun 15, 2008 at 08:08:52PM -0700, Sean McNeil wrote:
|> Cons:
|> audio pop is still there for me. I don't know if you committed changes
|> that should affect it. When I do fully resume and write to the device
|> hangs. Perhaps they are both related to something with DMA? I get
| I suspect this is
| Rearing its ugly head.

Thanks for the hint!

| Someone please tell me why I cant read that register successfully during
| resume???????
| Its as though the kernel caches it.

The only way it could "cache" it is if the iis memory mapped register
region of cpu space was literally marked as cacheable, because readl()
is just reading memory.  So I think you can read from it OK.

It doesn't necessarily follow that LRCK is actually toggling at that
time because nulling the test out get you working; something might be
done later that gets LRCK going subsequently.

For example I notice we disable IIS clock in suspend, this is re-enabled
by the time we start looking?  What if s3c24xx_i2s_trigger() ->
s3c24xx_snd_lrsync() happens before resume of IIS that re-enables the
unit clock?

- -Andy
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