Re: [PATCH v3 01/10] ARM: tegra: Set the sound card model that alsaucm expects

[Stephen Warren]

On 02/04/2015 02:13 AM, Tomeu Vizoso wrote:
> On 02/03/2015 05:35 PM, Stephen Warren wrote:
> > On 02/03/2015 06:13 AM, Tomeu Vizoso wrote:
> > > On 2 February 2015 at 22:08, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
> > > > On 01/28/2015 03:50 AM, Tomeu Vizoso wrote:
> > > > > Patches are on its way to add a config file to alsaucm for the Nyan
> > > > > boards. Use the same card ID that alsaucm will expect.
> > > >
> > > >
> > > > > diff --git a/arch/arm/boot/dts/tegra124-nyan-big.dts
> > > > > b/arch/arm/boot/dts/tegra124-nyan-big.dts
> > > >
> > > >
> > > > >           sound {
> > > > > -               compatible = "nvidia,tegra-audio-max98090-nyan-big",
> > > > > +               compatible = "nvidia,tegra-audio-max98090-nyan",
> > > > >                                "nvidia,tegra-audio-max98090";
> > > >
> > > >
> > > > I'm not convinced that removing the board-specific compatible value is a
> > > > great idea. What if we find we need to distinguish between different boards
> > > > that use this same binding in the future. That situation is exactly why we
> > > > have board-/SoC-specific values in compatible even if we don't immediately
> > > > use them.
> > >
> > > I understand the need of naming each component variant so they can be
> > > distinguished in the future, but in this case it's the exact same hw.
> >
> > That's not true. These are two different boards that are derived from
> > the same base design. The intent may be that they are the same, but the
> > whole point of board-specific compatible values is to cover the case
> > where mistakes and exceptions appear later.
>
> Fair enough.
>
> > > > > -               nvidia,model = "Acer Chromebook 13";
> > > > > +               nvidia,model = "GoogleNyan";
> > > >
> > > >
> > > > I believe this also technically breaks ABI, since some user-space tools use
> > > > the model to look up saved state. Can we not leave this as is, and just have
> > > > the UCM files know about both names?
> > >
> > > Well, "A13" isn't a great card id. Given that there's no users yet, I
> > > would prefer to take this chance to put a sane value in there. Btw,
> > > alsa-lib has now a UCM config for this and it uses the GoogleNyan card
> > > id (has been picked up already by OpenSUSE).
> >
> > "A13" didn't appear anywhere, did it? Perhaps that was a shorthand for
> > "Acer Chromebook 13". Yes, I agree we should use the user-visible model
> > number here; "Acer CB5" or perhaps "Acer CB5-xxx" whatever xxx actually is.
>
> Ok, so we can go with Acer-CB5-311 for the nyan big.
>
> Unfortunately there doesn't exist a single product id that corresponds
> with the nyan blaze, but at least four: K4K83UA, K4K11UA, K4K78UA and
> K4K23UA. The commercial name of the series that contain a blaze board is
> "HP Chromebook 14 G3", but that doesn't fit in the card id field (16 byte).

Oh, the 16-byte limit is rather annoying:-( Some of our existing DT 
files don't fit into that limit.

> What do you think of using GoogleNyanBig and GoogleNyanBlaze? Or maybe
> just NyanBig and NyanBlaze? IMO it's more important that the card ids
> correspond 1-to-1 to the hw than their recognizability, as it's not
> something that end users will be messing with.

I'm not entirely sure that the user won't ever see those values; don't 
some X11 GUI tools display them? Still, as you say there isn't too much 
we can do, so since these names are unique/complete I figure they're OK.
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