[RFC 10/12] omap: mcbsp: Move sidetone clock management to mach-omap2/mcbsp.c

Cousson, Benoit b-cousson at ti.com
Fri Jul 1 05:26:36 EDT 2011

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?


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