[Bug 74861] [hsw regression] Fast audio playback on Intel Haswell HDMI due to runtime pm

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=74861

--- Comment #44 from Daniel Fernández <dfmartinez at gmail.com> ---
(In reply to Mengdong Lin from comment #42)
> Hi Daniel,
> 
> Could you change the code to program fix M/N value to EM4/EM5 regsiter like
> this?
> 
> static void haswell_restore_bclk(struct azx *chip)
> {
> 	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
> 
> 	//azx_writew(chip, EM4, hda->bclk_m);
> 	//azx_writew(chip, EM5, hda->bclk_n);
> 	azx_writew(chip, EM4, 0x4);
> 	azx_writew(chip, EM5, 0x5a);
> }
> 
> The 0X4/0X5a is for 540MhZ CDLCK.

Good news! I applied the patch and works BUT only in some cases.

If I disconnect the power cable at AND no sound is routed through HDMI in that
moment sound starts to work at correct speed/pitch.

Make some research I noticed that azx_runtime_suspend is called when I
disconnect the power cable. I added a printk in azx_runtime_suspend() with a
counter to detect how many times is called and which are EM4 and EM5 values.

Results of tests made with HDMI cable connected.

When I unplug power cable WITH an application sound routed to HDMI the result
is:
[  221.162532]  *** M/N Values [1]: 0/37312
Sounds pitched up and wrong speed.


When I unplug power cable WITHOUT an application routed to HDMI and later use
HDMI sound result is:
[  256.856095]  *** M/N Values [2]: 4/75
And sound works perfect in correct pitch at correct speed and later if I replug
power cable continues sounding ok, at this moment HDMI sound works permanently
ok until I shutdown the system.

I attach the patch use to display M/N values.

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