Re: [RFC PATCH 00/34] sun8i-codec fixes and new features

From: Chen-Yu Tsai
Date: Mon Feb 17 2020 - 04:44:52 EST

On Mon, Feb 17, 2020 at 5:14 PM Maxime Ripard <maxime@xxxxxxxxxx> wrote:
> Hi,
> On Mon, Feb 17, 2020 at 12:42:16AM -0600, Samuel Holland wrote:
> > The sun8i-codec driver, as used in the Allwinner A33 and A64, currently
> > only exposes a small subset of the available hardware features. In order
> > to use the A64 in a smartphone (the PinePhone), I've added the necessary
> > functionality to the driver:
> > * The full set of supported DAI format options
> > * Support for AIF2 and AIF3
> > * Additional routing knobs
> > * Additional volume controls
> >
> > Unfortunately, due to preexisting issues with the driver, there are some
> > breaking changes, as explained further in the commit messages:
> > * The LRCK inversion issue means we need a new compatible for the A64.
> > * Some controls are named inaccurately, so they are renamed.
> > * Likewise, the DAPM widgets used in device trees were either named
> > wrong, or the device trees were using the wrong widgets in the first
> > place. (Specifically, the links between the analog codec and digital
> > codec happen at the ADC and DAC, not AIF1.)
> >
> > I tended to take the philosophy of "while I'm breaking things, I might
> > as well do them right", so I've probably made a few more changes than
> > absolutely necessary. I'm not sure about where all of the policy
> > boundaries are, about how far I should go to maintain compatibility. For
> > example, for the DT widget usage, I could:
> > * Rename everything and update the DTS files (which is what I did)
> > * Keep the old (misleading/wrong) name for the widgets, but repurpose
> > them to work correctly
> > (i.e. "ADC Left" would be named "AIF1 Slot 0 Left ADC", but it
> > would work just like "ADC Left" does in this patchset)
> > * Keep the old widgets around as a compatibility layer, but add new
> > widgets and update the in-tree DTS files to use them
> > (i.e. "ADC Left" would have a path from "AIF1 Slot 0 Left ADC",
> > but "AIF1 Slot 0 Left ADC" would be a no-op widget)
> > * Something else entirely
> I'm not sure this is really a concern here. We need to maintain the
> compatibility with old DT's, but those will have an A33 compatible
> too, and as far as I can see, you're not changing anything for that
> compatible, so we're in the clear?
> If not, then the third option would probably be the best, especially
> since it's only a couple of them.

Unfortunately the description for both chips are shared, and they're wrong.
So we probably need a new compatible (or a new driver)... or like options
2 or 3, keep the DT visible endpoints (but deprecate them), and route them
to a new set of proper widgets.