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

[Markus Schroetter]

Hello all,

if I may add to this; I agree with Daniel here. Geoffreys proposed
changes are already a big improvement to the usability. They avoid a lot
of confusion, especially for new users, caused by the hardware being out
of sync with alsamixer; and also helping with identifying the changes
that Windows did to the configuration from what I can tell.
Additionally, it makes it easier to just adjust the current
configuration after a reboot. Rather than having to either start from
scratch or work from restoring an already stored configuration.

Since I think it'd be an improvement for most users, I'd appreciate it
if these changes could be integrated until a better solution is available.

Best Regards,
Markus

On 07.06.21 17:12, Takashi Iwai wrote:
> On Mon, 07 Jun 2021 17:00:10 +0200,
> Vladimir Sadovnikov wrote:
>> Hello!
>>
>> I would like to say some words from my side.
>>
>> The Scarlett device (especially 18i20) is pretty complicated device
>> and holds a lot of settings in it's internal
>> configuration area (hardware and software).
>>
>> So this is not the only patch which will configure the driver in proper way.
>> Since the device stores it's internal state (and that's good for power
>> safety and mobility), ideally, we should get
>> the almost fully compatible mixer settings with the original Focusrite
>> Control Software.
>>
>> The huge amount of job I've already done i my fork of Geoffrey's driver:
>> https://github.com/sadko4u/focusrite-scarlett-backports/blob/master/prod-drv/mixer_scarlett_gen2.c
>>
>> So we're planning to work on integrating our changes into the common
>> patch sets and will submit changes here.
> Sure, I don't mean against the patches, this looks like an acceptable
> approach.  So don't worry, I'd take the patches once when the fixed
> version is submitted.
>
> However, from the system design POV, all those configurations should
> be a software issue, and ideally we shouldn't  rely on the hardware
> preset state which has been done *somehow* -- it may allow malfunction
> easily.  One thing I've learned over years is that you can never trust
> hardware :)
>
>
> Takashi
>
>> Best,
>> Vladimir
>>
>> 07.06.2021 10:23, Takashi Iwai пишет:
>>> 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
>>