On 2022-01-10 10:47 AM, Lad Prabhakar wrote:
Instead of recursively calling rz_ssi_pio_recv() use a while loop
to read the samples from RX fifo.
Recursion and loops are means for doing something repeatedly. Could you
specify _why_ such change was made i.e. the conversion from one method
into the other? I bet the code is not being changed for the sake of
changing it, the reason is simply missing in the commit message.
Please note that refactoring below function into while-loop has a side
effect: everything had to be indented by additional tab. Generally,
readability increases if function is shaped 'linearly'.
This also fixes an issue where the return value of rz_ssi_pio_recv()
was ignored when called recursively.
Fixes: 03e786bd4341 ("ASoC: sh: Add RZ/G2L SSIF-2 driver")
Reported-by: Pavel Machek <pavel@xxxxxxx>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
sound/soc/sh/rz-ssi.c | 68 ++++++++++++++++++++++---------------------
1 file changed, 35 insertions(+), 33 deletions(-)
diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c
index fa0cc08f70ec..37466f65c2b0 100644
--- a/sound/soc/sh/rz-ssi.c
+++ b/sound/soc/sh/rz-ssi.c
@@ -411,54 +411,56 @@ static int rz_ssi_pio_recv(struct rz_ssi_priv *ssi, struct rz_ssi_stream *strm)
{
struct snd_pcm_substream *substream = strm->substream;
struct snd_pcm_runtime *runtime;
+ bool done = false;
u16 *buf;
int fifo_samples;
int frames_left;
- int samples = 0;
+ int samples;
int i;
if (!rz_ssi_stream_is_valid(ssi, strm))
return -EINVAL;
runtime = substream->runtime;
- /* frames left in this period */
- frames_left = runtime->period_size - (strm->buffer_pos %
- runtime->period_size);
- if (frames_left == 0)
- frames_left = runtime->period_size;
- /* Samples in RX FIFO */
- fifo_samples = (rz_ssi_reg_readl(ssi, SSIFSR) >>
- SSIFSR_RDC_SHIFT) & SSIFSR_RDC_MASK;
-
- /* Only read full frames at a time */
- while (frames_left && (fifo_samples >= runtime->channels)) {
- samples += runtime->channels;
- fifo_samples -= runtime->channels;
- frames_left--;
- }
+ while (!done) {
I wonder if converting this into do-while isn't a better option. Maybe
I'm missing something but 'done' flag seems to be changed only as an
outcome of the last if-statement (last step) in this entire procedure.
Perhaps condition from said if-statement could also be moved into
'while' portion of do-while loop.
+ /* frames left in this period */
+ frames_left = runtime->period_size -
+ (strm->buffer_pos % runtime->period_size);
+ if (!frames_left)
+ frames_left = runtime->period_size;
+
+ /* Samples in RX FIFO */
+ fifo_samples = (rz_ssi_reg_readl(ssi, SSIFSR) >>
+ SSIFSR_RDC_SHIFT) & SSIFSR_RDC_MASK;
+
+ /* Only read full frames at a time */
+ samples = 0;
+ while (frames_left && (fifo_samples >= runtime->channels)) {
+ samples += runtime->channels;
+ fifo_samples -= runtime->channels;
+ frames_left--;
+ }
- /* not enough samples yet */
- if (samples == 0)
- return 0;
+ /* not enough samples yet */
+ if (!samples)
+ break;
- /* calculate new buffer index */
- buf = (u16 *)(runtime->dma_area);
- buf += strm->buffer_pos * runtime->channels;
+ /* calculate new buffer index */
+ buf = (u16 *)(runtime->dma_area);
Is the second pair of brackets needed?
+ buf += strm->buffer_pos * runtime->channels;
- /* Note, only supports 16-bit samples */
- for (i = 0; i < samples; i++)
- *buf++ = (u16)(rz_ssi_reg_readl(ssi, SSIFRDR) >> 16);
+ /* Note, only supports 16-bit samples */
+ for (i = 0; i < samples; i++)
+ *buf++ = (u16)(rz_ssi_reg_readl(ssi, SSIFRDR) >> 16);
- rz_ssi_reg_mask_setl(ssi, SSIFSR, SSIFSR_RDF, 0);
- rz_ssi_pointer_update(strm, samples / runtime->channels);
+ rz_ssi_reg_mask_setl(ssi, SSIFSR, SSIFSR_RDF, 0);
+ rz_ssi_pointer_update(strm, samples / runtime->channels);
- /*
- * If we finished this period, but there are more samples in
- * the RX FIFO, call this function again
- */
- if (frames_left == 0 && fifo_samples >= runtime->channels)
- rz_ssi_pio_recv(ssi, strm);
+ /* check if there are no more samples in the RX FIFO */
+ if (!(!frames_left && fifo_samples >= runtime->channels))
+ done = true;
+ }
return 0;
}
