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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