linux-kernel - Re: [linux-sunxi] [PATCH v6 1/3] ASoC: sun4i-i2s: incorrect regmap for A83T

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Date:   Tue, 27 Aug 2019 18:28:16 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Code Kipper <codekipper@...il.com>
Cc:     Maxime Ripard <mripard@...nel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linux-ALSA <alsa-devel@...a-project.org>,
        "Andrea Venturi (pers)" <be17068@...rbole.bo.it>
Subject: Re: [linux-sunxi] [PATCH v6 1/3] ASoC: sun4i-i2s: incorrect regmap
 for A83T

On Tue, Aug 27, 2019 at 4:35 PM Code Kipper <codekipper@...il.com> wrote:
>
> On Tue, 27 Aug 2019 at 10:01, Chen-Yu Tsai <wens@...e.org> wrote:
> >
> > On Tue, Aug 27, 2019 at 1:55 PM Code Kipper <codekipper@...il.com> wrote:
> > >
> > > On Tue, 27 Aug 2019 at 06:13, Chen-Yu Tsai <wens@...e.org> wrote:
> > > >
> > > > On Tue, Aug 27, 2019 at 2:07 AM <codekipper@...il.com> wrote:
> > > > >
> > > > > From: Marcus Cooper <codekipper@...il.com>
> > > > >
> > > > > The regmap configuration is set up for the legacy block on the
> > > > > A83T whereas it uses the new block with a larger register map.
> > > >
> > > > Looking at the code Allwinner previously released [1], that doesn't seem to be
> > > > the case. Keep in mind that the register map shown in the user manual is for
> > > > the TDM interface, which we don't actually support right now.
> > >
> > > Should it matter what we support right now?, the block according to the user
> > > manual shows the bigger range. I don't have a A83T device and from what I
> >
> > There are a total of four I2S controllers on the A83T. Currently three of them
> > are listed in the dtsi file, which are _not_ the one shown in the user manual.
> > The one shown is the fourth one, which is the TDM controller.
>
> The configuration for the A83T suggests that it's a mixture of old and
> new which I don't
> think is the case considering it was released around the same time as
> the H3. There
> is enough similarity between the blocks for it to still work. For
> example on the H6
> we referenced by mistake the H3 block and we still got audio (with
> only slight distortion).

The difference with the A83T here is large enough that if you play anything
it will simply stall. I already reported it as broken and Maxime has sent
fixes.

> I would suggest to validate all of the i2s blocks we need to test
> using the internal loopback
> as that will also cover capture.
>
> >
> > It's not like we haven't seen this before. IIRC the A64 also had two variants
> > of the I2S interface. The one coupled with the audio codec was different from
> > the others.
>
> Yes...but the i2s of the audio codec was documented in the audio codec
> section. I've used
> this device to ensure that I've not broken anything in the old block
> with these new changes.
>
> >
> > > gather not many users do. But the compatible for the H3 has been removed
> > > and replaced with the settings for the A83T which also has default settings in
> > > registers further up than SUNXI_RXCHMAP.
> >
> > I'll sync up with Maxime on this.
> >
> > > >
> > > > The file shows the base address as 0x01c22800, and the last defined register
> > > > is SUNXI_RXCHMAP at 0x3c.
> > > >
> > > > The I2S driver [2] also shows that it is the old register map size, but with
> > > > TX_FIFO and INT_STA swapped around. This might mean that it would need a
> > > > separate regmap_config, as the read/write callbacks need to be changed to
> > > > fit the swapped registers.
> > > >
> > > > Finally, the TDM driver [3], which matches the TDM section in the manual, shows
> > > > a larger register map.
> > > >
> > > > A83T is SUN8IW6, while SUN8IW7 refers to the H3.
> > >
> > > Since when have we trusted Allwinner code?, the TDM labelled block
> > > clearly supports
> >
> > Since they haven't listed the I2S block in the user manual, so that is what we
> > have to go by.
> >
> > The TDM section in the user manual only lists the block at 0x1c23000. The memory
> > map says DAUDIO-[012] for addresses 0x1c22000, 0x1c22400, 0x1c22800, and TDM for
> > address 0x1c23000. One would assume this meant these are somewhat different.
> >
> > > I2S. The biggest use case for this block is getting HDMI audio working
> > > on the newer
> >
> > I understand that.
> >
> > > devices(LibreELEC nightlies has a user base of over 300) and I've tested this on
> > > numerous set ups over the last couple of years.
> >
> > Tested on the H3, correct?
>
> Yes....but only with the additional changes for multi-channel with my
> LibreELEC build.
> These changes I tested on my pine64 before pushing upstream.
>
> >
> > > Failing that reverting (3e9acd7ac693: "ASoC: sun4i-i2s: Remove
> > > duplicated quirks structure")
> > > would help.
> >
> > I'll take a look. IIRC it worked with the old layout, with the two registers
> > swapped, playing standard 48 KHz / 16 bit audio when I added supported for
> > the A83T. Then again maybe the stars were perfectly aligned. At the very least
> > we could separate A83T and H3 as you suggested.

Maxime has sent a patch reverting the merger.

ChenYu