On 7/1/2011 11:23 AM, Paul Walmsley wrote:
+ Benoît
Hello Jarkko
On Fri, 1 Jul 2011, Jarkko Nikula wrote:
Active sidetone requires that McBSP interface clock doesn't idle and there
is no mechanism in hwmod to turn autoidling on/off in runtime. McBSP2 and 3
in OMAP34xx share their interface clock with McBSP sidetone module and
that interface clock must be active when the sidetone is operating.
Sidetone has its own autoidle bit which should keep the interface clock
active but it is broken. Putting the McBSP core to no-idle mode when the
sidetone is active is no good either since it results to higher power
consumption when using the threshold based DMA transfers.
In the hwmod code/data, we've got the OCPIF_SWSUP_IDLE flag that can be
set on a struct omap_hwmod_ocp_if. I think this is probably what's needed
here. The only problem is that we haven't linked that to the clock code
to deny idle on the interface clock yet (see omap_hwmod.c:_setup()).
Adding that code in, plus adding that OCPIF_SWSUP_IDLE flag to the
McBSP2/3 data, seems like the right approach here.
I guess we also will need some basic usecounting for denying idle in the
clock code.
Otherwise these direct register manipulations of clock registers, outside
the clock code, could turn into a mess :-(
AFAIR Kishon did submit some patches to expose this feature to the
driver through omap_device API. The point is that other broken IP like
SDMA of USB will require such feature.
Didn't we pull them?
Benoit
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