[Audio Driver Low power state]

[pramod gurav]

Hi Gomathi,

This is not the exact place for this query as this list is for people
having queries on Kernel in general. You query mostly is on audio on
certain platform. Check what is the support list for that like alsa-devel
or alsa mailing list.


On Wed, Mar 26, 2014 at 9:35 AM, Gomathi Kumar <gomathi.techgig at gmail.com>wrote:

> Hi all,
>
> I am new to kernel work and am trying to understand the low power state of
> audio driver.
>
> I am using ALC262 codec, hda_intel and 3.10 kernel code.
> In this codec, d3_stop_clk flag is not set. So in the code flow I was able
> to understand the following.
>
> if (!codec->pm_down_notified &&
>         !bus->power_keep_link_on && (state & AC_PWRST_CLK_STOP_OK))
>
> this particular condition in hda_power_work function fails, as
> power_keep_link_on flag is directly based on d3_stop_clk flag.
>
> codec->d3_stop_clk = snd_hda_codec_get_supported_ps(codec, fg,
>                                         AC_PWRST_CLKSTOP);
>
> I modified the if condition to not check the power_keep_link_on flag.
> After this change the audio is consuming lesser power, but I am not able to
> see it going to suspend/runtime suspend.
>
> *Please clarify what is happening when I modify the if condition and how
> audio device is consuming low power?*
>
> *Also please help me understand, the significance of flags EPSS and
> D3_STOP_CLK and if they can be set by software code. *
>
> Thanks,
> Gomathi
>
>
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>


-- 
Thanks and Regards
Pramod
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