[alsa-devel] [PATCH 07/11] ASoC: omap-mcbsp: Sidetone: Use SIDLE bits in SYSCONFIG register to select noidle mode
ricardo.neri at ti.com
Thu Aug 9 17:15:39 CEST 2012
On 08/09/2012 02:05 AM, Peter Ujfalusi wrote:
> Hi Ricardo,
> On 08/09/2012 01:12 AM, Ricardo Neri wrote:
>> Is this another case in which it is required to change the idle-mode on a
>> per-use-case basis? In the past I was trying to do the same with HDMI . In
>> that case it was decided to add the HWMOD_SWSUP_SIDLE to hwmod data with the
>> drawback of using no-idle/force-idle rather than smart-idle.
> This only concerns use case on OMAP3 when the sidetone is in use. In all other
> use cases we want to use smart-idle (music playback, FM TX/RX, etc).
> The main problem here is that the sidetone block have broken sidle line, it
> can not prevent McBSP iclk to be gated.
> The sidetone block is using the ICLK of the McBSP port (OMAP3 has ST block
> attached to McBSP2 and 3 ports only).
The situation was similar with HDMI. We need no-idle only when playing
audio and smart-idle in all other use cases. With HWMOD_SWSUP_SIDLE we
are in no-idle/force-idle all the time. :/
>>  http://email@example.com/msg60226.html
>>  http://firstname.lastname@example.org/msg70463.html
>>  http://email@example.com/msg70653.html
>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
>>> sound/soc/omap/mcbsp.c | 18 ++++++++++++++----
>>> sound/soc/omap/mcbsp.h | 1 +
>>> 2 files changed, 15 insertions(+), 4 deletions(-)
>>> diff --git a/sound/soc/omap/mcbsp.c b/sound/soc/omap/mcbsp.c
>>> index c870023..e008898 100644
>>> --- a/sound/soc/omap/mcbsp.c
>>> +++ b/sound/soc/omap/mcbsp.c
>>> @@ -257,8 +257,15 @@ static void omap_st_on(struct omap_mcbsp *mcbsp)
>>> unsigned int w;
>>> - if (mcbsp->pdata->enable_st_clock)
>>> - mcbsp->pdata->enable_st_clock(mcbsp->id, 1);
>>> + /*
>>> + * Sidetone uses McBSP ICLK - which must not idle when sidetones
>>> + * are enabled or sidetones start sounding ugly.
>>> + */
>>> + w = MCBSP_READ(mcbsp, SYSCON);
>>> + mcbsp->st_data->mcbsp_sidle = (w >> 3) & 0x3;
>>> + w &= ~SIDLEMODE(0x3);
>>> + w |= SIDLEMODE(0x1);
>>> + MCBSP_WRITE(mcbsp, SYSCON, w);
>> Wouldn't this create a mismatch between the SYSCONFIG register and McBSP
> We modify the bits runtime (if the ST is enabled), after the hwmod already
> configured the McBSP port to s-idle. We change the McBSP port's s-idle mode
> back to it's original before pm_runtime_put().
> Previously we did the same thing in PRCM level which was as ugly as this
> workaround with the penalty of a callback function to mach-omap2 since we can
> only got access to PRCM register API there.
>> Perhaps this could be done with a future omap_hwmod API?
> But there's no such an API and I'm not aware any ongoing effort to have one.
> Still the issue mostly remains since we need to modify other block's s-idle
> mode. If sidetone block is enabled we need to change the McBSP port's s-idle
> mode to no-idle.
Would omap_hwmod_set_slave_idlemode make the workaround look less ugly?
In this case you are changing other block's idle-mode, though.
> In most of the use cases the McBSP need to be in smart-idle mode since it
> provides significant power saving.
Yes, I was just trying to use this case to justify the need of a driver
to be able to set the idle-mode for particular use cases. It would be
nice to be able to use an API (present or future) to set to no-idle if
required by a particular use-case and still be able to take advantage of
smart-idle in other use cases.
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