Hi, patch_realtek.c maintainer:
I see one issue that reboot from windows and boot to ubuntu, the audio
lost from speaker, I suspect there are some bugs in patch_realtek.c drivers,
the device is ALC295 and the device id is 0x10ec0295.
I have done the below experiments:
1. reboot from windows to windows, the audio is persist .
2. reboot from windows to ubuntu, the audio lost from speaker, but can hear if
I hotplug one earphone.
3. if the issue reproduce after reboot from windows, reboot the ubuntu can't
restore the audio, I suspect it's warm reset.
4. if I write the port 0xcf9 with 0xe to do cold reset, the audio can restore.
5. if I do suspend/resume, the audio can restore, I suspect do cold boot and
suspend will trigger the platform reset to reset the ALC295.
6. if I do double function reset (write the verb 0x7ff in alc_init), the audio
is still can't restore.
snd_hda_codec_write(codec, 0x01, 0, AC_VERB_SET_CODEC_RESET, 0); /* Function
reset */
snd_hda_codec_write(codec, 0x01, 0, AC_VERB_SET_CODEC_RESET, 0); /* double
Function reset */
7. the issue is first found on kernel 4.19.50, I still see the issue with the
latest kernel 5.2-rc2, is it possible windows change some default registers,
but ALC295 don't initialize the register?
