[PATCH] ALSA: hda: Refactor Intel NHLT init

[Cezary Rojewski]

On 2020-04-23 13:24, Takashi Iwai wrote:
> On Thu, 23 Apr 2020 13:21:36 +0200,
> Cezary Rojewski wrote:
>>
>> NHLT fetch based on _DSM prevents ACPI table override mechanism from
>> being utilized. Make use of acpi_get_table to enable it and get rid of
>> redundant code.
>>
>> Signed-off-by: Cezary Rojewski <cezary.rojewski at intel.com>
> 
> This looks like a nice cleanup and I'll happily apply if anyone can
> test with the actual hardware -- currently mine has no DSP, so unable
> to check.
> 
> 
> thanks,
> 
> Takashi
> 

NHLT override method has been added for internal use half a year ago and 
is for some time the default method within our CI. This is tested on a 
wide spread of hardware, that is any Intel AVS archtecture, including 
production laptops.

Actual override works like any SSDT/ DSDT, e.g. usage can be found at:
https://github.com/thesofproject/acpi-scripts

and original:
https://wiki.up-community.org/Pinout_UP2#Installing_ACPI_overrides_to_enable_spi_in_userspace

Early this year I've pushed the initiative to finally shatter bounds of 
mystery surrounding NHLT in Linux and make it available to community. 
Erik and Robert helped me in ACPICA part, patch link:
https://patchwork.kernel.org/patch/11463235/

Spec can now be found at:
https://01.org/blogs/intel-smart-sound-technology-audio-dsp

This has been sanctioned by Intel Legal and acked by Marcin Obara, NHLT 
author so no worries about spec disappearing like it did in 2016.

Czarek