Re: [PATCH v6 02/14] ASoC: sun4i-i2s: Change set_chan_cfg() params

From: Samuel Holland
Date: Mon Oct 12 2020 - 22:42:04 EST

On 10/12/20 7:15 AM, Maxime Ripard wrote:
> Hi,
>
> On Mon, Oct 05, 2020 at 03:23:12PM +0200, Clément Péron wrote:
>> On Mon, 5 Oct 2020 at 14:13, Maxime Ripard <maxime@xxxxxxxxxx> wrote:
>>>
>>> On Sat, Oct 03, 2020 at 04:19:38PM +0200, Clément Péron wrote:
>>>> As slots and slot_width can be set manually using set_tdm().
>>>> These values are then kept in sun4i_i2s struct.
>>>> So we need to check if these values are setted or not
>>>> in the struct.
>>>>
>>>> Avoid to check for this logic in set_chan_cfg(). This will
>>>> duplicate the same check instead pass the required values
>>>> as params to set_chan_cfg().
>>>>
>>>> This will also avoid a bug when we will enable 20/24bits support,
>>>> i2s->slot_width is not actually used in the lrck_period computation.
>>>>
>>>> Suggested-by: Samuel Holland <samuel@xxxxxxxxxxxx>
>>>> Signed-off-by: Clément Péron <peron.clem@xxxxxxxxx>
>>>> ---
>>>> sound/soc/sunxi/sun4i-i2s.c | 36 ++++++++++++++----------------------
>>>> 1 file changed, 14 insertions(+), 22 deletions(-)
>>>>
>>>> diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
>>>> index c5ccd423e6d3..1f577dbc20a6 100644
>>>> --- a/sound/soc/sunxi/sun4i-i2s.c
>>>> +++ b/sound/soc/sunxi/sun4i-i2s.c
>>>> @@ -177,8 +177,9 @@ struct sun4i_i2s_quirks {
>>>> unsigned long (*get_bclk_parent_rate)(const struct sun4i_i2s *);
>>>> s8 (*get_sr)(const struct sun4i_i2s *, int);
>>>> s8 (*get_wss)(const struct sun4i_i2s *, int);
>>>> - int (*set_chan_cfg)(const struct sun4i_i2s *,
>>>> - const struct snd_pcm_hw_params *);
>>>> + int (*set_chan_cfg)(const struct sun4i_i2s *i2s,
>>>> + unsigned int channels, unsigned int slots,
>>>> + unsigned int slot_width);
>>>> int (*set_fmt)(const struct sun4i_i2s *, unsigned int);
>>>> };
>>>>
>>>> @@ -414,10 +415,9 @@ static s8 sun8i_i2s_get_sr_wss(const struct sun4i_i2s *i2s, int width)
>>>> }
>>>>
>>>> static int sun4i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
>>>> - const struct snd_pcm_hw_params *params)
>>>> + unsigned int channels, unsigned int slots,
>>>> + unsigned int slot_width)
>>>> {
>>>> - unsigned int channels = params_channels(params);
>>>> -
>>>> /* Map the channels for playback and capture */
>>>> regmap_write(i2s->regmap, SUN4I_I2S_TX_CHAN_MAP_REG, 0x76543210);
>>>> regmap_write(i2s->regmap, SUN4I_I2S_RX_CHAN_MAP_REG, 0x00003210);
>>>> @@ -434,15 +434,11 @@ static int sun4i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
>>>> }
>>>>
>>>> static int sun8i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
>>>> - const struct snd_pcm_hw_params *params)
>>>> + unsigned int channels, unsigned int slots,
>>>> + unsigned int slot_width)
>>>> {
>>>> - unsigned int channels = params_channels(params);
>>>> - unsigned int slots = channels;
>>>> unsigned int lrck_period;
>>>>
>>>> - if (i2s->slots)
>>>> - slots = i2s->slots;
>>>> -
>>>> /* Map the channels for playback and capture */
>>>> regmap_write(i2s->regmap, SUN8I_I2S_TX_CHAN_MAP_REG, 0x76543210);
>>>> regmap_write(i2s->regmap, SUN8I_I2S_RX_CHAN_MAP_REG, 0x76543210);
>>>> @@ -467,11 +463,11 @@ 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;
>>>>
>>>> default:
>>>> @@ -490,15 +486,11 @@ static int sun8i_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
>>>> }
>>>>
>>>> static int sun50i_h6_i2s_set_chan_cfg(const struct sun4i_i2s *i2s,
>>>> - const struct snd_pcm_hw_params *params)
>>>> + unsigned int channels, unsigned int slots,
>>>> + unsigned int slot_width)
>>>> {
>>>> - unsigned int channels = params_channels(params);
>>>> - unsigned int slots = channels;
>>>> unsigned int lrck_period;
>>>>
>>>> - if (i2s->slots)
>>>> - slots = i2s->slots;
>>>> -
>>>> /* Map the channels for playback and capture */
>>>> regmap_write(i2s->regmap, SUN50I_H6_I2S_TX_CHAN_MAP0_REG, 0xFEDCBA98);
>>>> regmap_write(i2s->regmap, SUN50I_H6_I2S_TX_CHAN_MAP1_REG, 0x76543210);
>>>> @@ -525,11 +517,11 @@ static int sun50i_h6_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;
>>>>
>>>> default:
>>>> @@ -565,7 +557,7 @@ static int sun4i_i2s_hw_params(struct snd_pcm_substream *substream,
>>>> if (i2s->slot_width)
>>>> slot_width = i2s->slot_width;
>>>>
>>>> - ret = i2s->variant->set_chan_cfg(i2s, params);
>>>> + ret = i2s->variant->set_chan_cfg(i2s, channels, slots, slot_width);
>>>
>>> Isn't slots and slot_width set to 0 here ?
>>
>> No, there is still a check before calling the set_cfg function.
>>
>> unsigned int slot_width = params_physical_width(params);
>> unsigned int channels = params_channels(params);
>> unsigned int slots = channels;
>>
>> if (i2s->slots)
>> slots = i2s->slots;
>>
>> if (i2s->slot_width)
>> slot_width = i2s->slot_width;
>>
>> ret = i2s->variant->set_chan_cfg(i2s, channels, slots, slot_width);
>>
>> So slot_width will be equal to params_physical_width(params);
>> like before
>
> Still, it's not obvious what slots and slot_width are going to be set to
> in a non-TDM setup where that doesn't really make much sense.

My understanding is:

"slots" is channels per frame + padding slots, regardless of format.
"slot_width" is bits per sample + padding bits, regardless of format.

Some formats may require or prohibit certain padding, but that has no
effect on the definitions.

That seems clear to me? At least that's what I implemented (and you
acked) in sun8i-codec.

> I assume you want to reduce the boilerplate, then we can make an helper
> to get the frame size and the number of channels / slots if needed

What would you name the return values, if not "slots" and "slot_width"?
"channels" and "word_size" would be inaccurate, because those terms
refer to the values without padding.

> Maxime

Cheers,
Samuel