[PATCH 0/2] ALSA: usb-audio: scarlett2: Read all configuration at init time

[Takashi Iwai]

On Sun, 06 Jun 2021 16:16:44 +0200,
Geoffrey D. Bennett wrote:
> 
> These two patches add support for reading the mixer volumes and mux
> configuration from the hardware when the driver is initialising.
> 
> Previously the ALSA volume controls were initialised to zero and the
> mux configuration set to a fixed default instead of being initialised
> to match the hardware state.
> 
> The ALSA controls for the Scarlett Gen 2 interfaces should now always
> be in sync with the hardware. Thanks to Vladimir Sadovnikov for
> figuring out how to do this.
> 
> Takashi, if these pass your review, I believe that they are
> appropriate for:
> #Cc: stable at vger.kernel.org

Well, in general, having a proper fixed value for the initial mixer
value is the right thing, which is a part of the driver's role.
Though, in snd-usb-audio, we don't set up the initial values just
because of laziness; since the topology in USB audio is variable per
device and often hard to parse correctly, it's difficult to determine
the suitable initial values, hence we leave untouched.  So, in that
sense, setting the zero isn't wrong, rather safer, per se.

However, Scarlett 2 seems to want to be different; it has already some
initialization code to read the existing configs.  So this change
sounds more or less acceptable.  But it's questionable whether it's
really for stable as a "fix".

In anyway, please fix the bug ktest bot spotted, the missing endian
conversions and resubmit.


thanks,

Takashi