linux-kernel - Re: [PATCH v9 01/14] ASoC: sun4i-i2s: Change set_chan

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Date:   Thu, 29 Oct 2020 20:20:51 -0500
From:   Samuel Holland <samuel@...lland.org>
To:     Clément Péron <peron.clem@...il.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     Maxime Ripard <mripard@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        devicetree <devicetree@...r.kernel.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Linux-ALSA <alsa-devel@...a-project.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Takashi Iwai <tiwai@...e.com>,
        Marcus Cooper <codekipper@...il.com>,
        linux-sunxi <linux-sunxi@...glegroups.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v9 01/14] ASoC: sun4i-i2s: Change set_chan_cfg() params

On 10/27/20 4:43 PM, Clément Péron wrote:
> Hi Pierre-Louis,
> 
> On Tue, 27 Oct 2020 at 19:59, Pierre-Louis Bossart
> <pierre-louis.bossart@...ux.intel.com> wrote:
>>
>>
>>> @@ -452,11 +454,11 @@ static int sun8i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
>>>       case SND_SOC_DAIFMT_DSP_B:
>>>       case SND_SOC_DAIFMT_LEFT_J:
>>>       case SND_SOC_DAIFMT_RIGHT_J:
>>> -             lrck_period = params_physical_width(params) * slots;
>>> +             lrck_period = slot_width * slots;
>>>               break;
>>>
>>>       case SND_SOC_DAIFMT_I2S:
>>> -             lrck_period = params_physical_width(params);
>>> +             lrck_period = slot_width;
>>>               break;
>>
>> Aren't I2S, LEFT_J and RIGHT_J pretty much the same in terms of lrclk
>> rate/period? the only thing that can change is the polarity, no?
>>
>> Not sure why it's handled differently here?
> 
> I just had a look at the User Manual for H3 and H6 and I didn't find
> any reason why LEFT_J and RIGHT_J should be computed in a different
> way as I2S.

Yes, and the manual explicitly groups LEFT_J and RIGHT_J with I2S when
describing this field:

   PCM Mode: Number of BCLKs within (Left + Right) channel width.
   I2S/Left-Justified/Right-Justified Mode: Number of BCLKs within each
individual channel width(Left or Right)

So I agree that the code is wrong here.

Regards,
Samuel

> Also the commit introducing this doesn't mention it.
> 7ae7834ec446 ("ASoC: sun4i-i2s: Add support for DSP formats")
> 
> I can't test it with my board but if nobody complains about it, I will
> introduce a fix for this in the next version and change this also for
> H6.
> 
> Thanks for your review,
> Clement
>