On Tue, Aug 04, 2020 at 12:03:46AM -0700, Nicolin Chen wrote:
> On Tue, Aug 04, 2020 at 12:22:53PM +0800, Shengjiu Wang wrote:
>
> > > > Btw, do we need similar change for TRIGGER_STOP?
> > >
> > > This is a good question. It is better to do change for STOP,
> > > but I am afraid that there is no much test to guarantee the result.
>
> > Maybe we can do this change for STOP.
>
> The idea looks good to me...(check inline comments)
>
> > diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> > index 1c0e06bb3783..6e4be398eaee 100644
> > --- a/sound/soc/fsl/fsl_sai.c
> > +++ b/sound/soc/fsl/fsl_sai.c
> > @@ -517,6 +517,37 @@ static int fsl_sai_hw_free(struct
> > snd_pcm_substream *substream,
> > return 0;
> > }
> >
> > +static void fsl_sai_config_disable(struct fsl_sai *sai, bool tx)
> > +{
> > + unsigned int ofs = sai->soc_data->reg_offset;
> > + u32 xcsr, count = 100;
> > +
> > + regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs),
> > + FSL_SAI_CSR_TERE, 0);
> > +
> > + /* TERE will remain set till the end of current frame */
> > + do {
> > + udelay(10);
> > + regmap_read(sai->regmap, FSL_SAI_xCSR(tx, ofs), &xcsr);
> > + } while (--count && xcsr & FSL_SAI_CSR_TERE);
> > +
> > + regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs),
> > + FSL_SAI_CSR_FR, FSL_SAI_CSR_FR);
> > +
> > + /*
> > + * For sai master mode, after several open/close sai,
> > + * there will be no frame clock, and can't recover
> > + * anymore. Add software reset to fix this issue.
> > + * This is a hardware bug, and will be fix in the
> > + * next sai version.
> > + */
> > + if (!sai->is_slave_mode) {
> > + /* Software Reset for both Tx and Rx */
>
> Remove "for both Tx and Rx"
>
> > /* Check if the opposite FRDE is also disabled */
> > regmap_read(sai->regmap, FSL_SAI_xCSR(!tx, ofs), &xcsr);
> > + if (sai->synchronous[tx] && !sai->synchronous[!tx] && !(xcsr & FSL_SAI_CSR_FRDE))
> > + fsl_sai_config_disable(sai, !tx);
>
> > + if (sai->synchronous[tx] || !sai->synchronous[!tx] || !(xcsr & FSL_SAI_CSR_FRDE))
> > + fsl_sai_config_disable(sai, tx);
>
> The first "||" should probably be "&&".
>
> The trigger() logic is way more complicated than a simple cleanup
> in my opinion. Would suggest to split RMR part out of this change.
>
> And for conditions like "sync[tx] && !sync[!tx]", it'd be better
> to have a helper function to improve readability:
>
> /**
> * fsl_sai_dir_is_synced - Check if stream is synced by the opposite stream
> *
> * SAI supports synchronous mode using bit/frame clocks of either Transmitter's
> * or Receiver's for both streams. This function is used to check if clocks of
> * current stream's are synced by the opposite stream.
Aww..this should be a generic function, so drop "current":
* or Receiver's for both streams. This function is used to check if clocks of
* the stream's are synced by the opposite stream.
> *
> * @sai: SAI context
> * @dir: direction of current stream
Ditto:
* @dir: stream direction
Thanks.
-----
> */
> static inline bool fsl_sai_dir_is_synced(struct fsl_sai *sai, int dir)
> {
> int adir = (dir == TX) ? RX : TX;
>
> /* current dir in async mode while opposite dir in sync mode */
> return !sai->synchronous[dir] && sai->synchronous[adir];
> }
>
> Then add more comments in trigger:
>
> static ...trigger()
> {
> bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
> int adir = tx ? RX : TX;
> int dir = tx ? TX : RX;
>
> // ....
> {
> // ...
>
> /* Check if the opposite FRDE is also disabled */
> regmap_read(sai->regmap, FSL_SAI_xCSR(!tx, ofs), &xcsr);
>
> /*
> * If opposite stream provides clocks for synchronous mode and
> * it is inactive, disable it before disabling the current one
> */
> if (fsl_sai_dir_is_synced(adir) && !(xcsr & FSL_SAI_CSR_FRDE))
> fsl_sai_config_disable(sai, adir);
>
> /*
> * Disable current stream if either of:
> * 1. current stream doesn't provide clocks for synchronous mode
> * 2. current stream provides clocks for synchronous mode but no
> * more stream is active.
> */
> if (!fsl_sai_dir_is_synced(dir) || !(xcsr & FSL_SAI_CSR_FRDE))
> fsl_sai_config_disable(sai, dir);
>
> // ...
> }
> // ....
> }
>
> Note, in fsl_sai_config_disable(sai, dir):
> bool tx = dir == TX;
>
> Above all, I am just drafting, so please test it thoroughly :)
