Re: [linux-sunxi] [PATCH v5 4/7] ASoC: sunxi: Add sun8i I2S driver

Maxime Ripard
2016-11-07T20:05:05Z

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Hi,

On Sun, Nov 06, 2016 at 07:02:48PM +0100, Jean-Francois Moine wrote:
> On Sun, 23 Oct 2016 09:33:16 +0800
> Chen-Yu Tsai <wens@csie.org> wrote:
>
> > On Fri, Oct 21, 2016 at 4:36 PM, Jean-Francois Moine <moinejf@free.fr> wrote:
> > > This patch adds I2S support to sun8i SoCs as the A83T and H3.
> > >
> > > Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
> > > ---
> > > Note: This driver is closed to the sun4i-i2s except that:
> > > - it handles the H3
> >
> > If it's close to sun4i-i2s, you should probably rework that one to support
> > the newer SoCs.
>
> I started to add the H3 into the sun4i-i2s, but I am blocked with
> regmap.
> Many H3 registers are common with the A10, but some of them have more
> or less fields, the fields may be at different offsets. And, finally,
> some registers are completely different.
> This would not raise any problem, except with regmap which is really
> painful.

That's weird, because regmap's regmap_field should make that much
easier.

> As I may understood, regmap is used to simplify suspend/resume, but, is
> it useful to save the I2S register on suspend?
> Practically, I am streaming some tune on my device. I suspend it for
> any reason. The next morning, I resume it. Are you sure I want to
> continue to hear the end of the tune?
>
> I better think that streaming should be simply stopped on suspend.

You're mistaken. The code in there is for *runtime* suspend, ie when
the device is no longer used, so that case shouldn't even happen at
all.

(And real suspend isn't supported anyway)

> Then, there is no need to save the playing registers, and, here I am,
> there is no need to use regmap.
>
> May I go this way?

No, please don't. regmap is also providing very useful features, such
as access to all the registers through debugfs, or tracing. What
exactly feels painful to you?

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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