On Mon, Jun 15, 2020 at 01:56:18PM +0800, Shengjiu Wang wrote:
> For mono channel, SSI will switch to Normal mode.
>
> In Normal mode and Network mode, the Word Length Control bits
> control the word length divider in clock generator, which is
> different with I2S Master mode (the word length is fixed to
> 32bit), it should be the value of params_width(hw_params).
>
> The condition "slots == 2" is not good for I2S Master mode,
> because for Network mode and Normal mode, the slots can also
> be 2. Then we need to use (ssi->i2s_net & SSI_SCR_I2S_MODE_MASK)
> to check if it is I2S Master mode.
The fsl_ssi_set_bclk is only called when fsl_ssi_is_i2s_master,
though I agree that that line of comments sounds confusing now.
> So we refine the famula for mono channel, otherwise there
famula => formula?
> will be sound issue for S24_LE.
>
> Fixes: b0a7043d5c2c ("ASoC: fsl_ssi: Caculate bit clock rate using slot number and width")
> Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> ---
> changes in v2
> - refine patch for Network mode and Normal mode.
>
> sound/soc/fsl/fsl_ssi.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c
> index bad89b0d129e..cbf67d132fda 100644
> --- a/sound/soc/fsl/fsl_ssi.c
> +++ b/sound/soc/fsl/fsl_ssi.c
> @@ -678,7 +678,8 @@ static int fsl_ssi_set_bclk(struct snd_pcm_substream *substream,
> struct regmap *regs = ssi->regs;
> u32 pm = 999, div2, psr, stccr, mask, afreq, factor, i;
> unsigned long clkrate, baudrate, tmprate;
> - unsigned int slots = params_channels(hw_params);
> + unsigned int channels = params_channels(hw_params);
> + unsigned int slots;
> unsigned int slot_width = 32;
> u64 sub, savesub = 100000;
> unsigned int freq;
> @@ -688,9 +689,15 @@ static int fsl_ssi_set_bclk(struct snd_pcm_substream *substream,
> /* Override slots and slot_width if being specifically set... */
> if (ssi->slots)
> slots = ssi->slots;
> - /* ...but keep 32 bits if slots is 2 -- I2S Master mode */
> - if (ssi->slot_width && slots != 2)
> - slot_width = ssi->slot_width;
> + else
> + /* Apply two slots for mono channel, because DC = 2 */
> + slots = (channels == 1) ? 2 : channels;
> +
> + /* ...but keep 32 bits if I2S Master mode */
> + if ((ssi->i2s_net & SSI_SCR_I2S_MODE_MASK) != SSI_SCR_I2S_MODE_MASTER ||
> + channels == 1)
> + slot_width = ssi->slot_width ? ssi->slot_width :
This looks very complicated...can you review and try mine?
(Basically, take 32-bit out of default but force it later)
@@ -678,8 +678,9 @@ static int fsl_ssi_set_bclk(struct snd_pcm_substream *substream,
struct regmap *regs = ssi->regs;
u32 pm = 999, div2, psr, stccr, mask, afreq, factor, i;
unsigned long clkrate, baudrate, tmprate;
- unsigned int slots = params_channels(hw_params);
- unsigned int slot_width = 32;
+ unsigned int channels = params_channels(hw_params);
+ unsigned int slot_width = params_width(hw_params);
+ unsigned int slots = 2;
u64 sub, savesub = 100000;
unsigned int freq;
bool baudclk_is_used;
@@ -688,10 +689,16 @@ static int fsl_ssi_set_bclk(struct snd_pcm_substream *substream,
/* Override slots and slot_width if being specifically set... */
if (ssi->slots)
slots = ssi->slots;
- /* ...but keep 32 bits if slots is 2 -- I2S Master mode */
- if (ssi->slot_width && slots != 2)
+ if (ssi->slot_width)
slot_width = ssi->slot_width;
+ /*
+ * ...but force 32 bits for stereo audio. Note that mono audio is also
+ * sent in 2 slots via NORMAL mode, so check both slots and channels.
+ */
+ if (slots == 2 && channels == 2)
+ slot_width = 32;
+
/* Generate bit clock based on the slot number and slot width */
freq = slots * slot_width * params_rate(hw_params);
