diff mbox series

[v2,1/5] ASoC: sh: rz-ssi: Drop calling rz_ssi_pio_recv() recursively

Message ID 20220115012303.29651-2-prabhakar.mahadev-lad.rj@bp.renesas.com (mailing list archive)
State Accepted
Delegated to: Kieran Bingham
Headers show
Series ASoC: sh: rz-ssi: Code cleanup and fixes | expand

Commit Message

Lad Prabhakar Jan. 15, 2022, 1:22 a.m. UTC 
Instead of recursively calling rz_ssi_pio_recv() use a loop instead
to read the samples from RX fifo.

Inspiration for this patch is to avoid recursion, as recursion is
unwelcome in kernel due to limited stack use. Also to add this driver
will later be used on RZ/A2 SoC's which runs with limited memory.

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@denx.de>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v1->v2
* Used a do while loop
* Fixed comments pointed by Cezary.
---
 sound/soc/sh/rz-ssi.c | 65 +++++++++++++++++++++----------------------
 1 file changed, 31 insertions(+), 34 deletions(-)

Comments

Cezary Rojewski Jan. 19, 2022, 1:35 p.m. UTC | #1 
On 2022-01-15 2:22 AM, Lad Prabhakar wrote:
> Instead of recursively calling rz_ssi_pio_recv() use a loop instead
> to read the samples from RX fifo.
> 
> Inspiration for this patch is to avoid recursion, as recursion is
> unwelcome in kernel due to limited stack use. Also to add this driver
> will later be used on RZ/A2 SoC's which runs with limited memory.
> 
> 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@denx.de>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
> v1->v2
> * Used a do while loop
> * Fixed comments pointed by Cezary.

Apart from my previous suggestions which have already been addressed, I 
don't see any issues with the patch, so:

Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>


Regards,
Czarek
Mark Brown Jan. 25, 2022, 10:22 a.m. UTC | #2 
On Sat, Jan 15, 2022 at 01:22:59AM +0000, Lad Prabhakar wrote:
> Instead of recursively calling rz_ssi_pio_recv() use a loop instead
> to read the samples from RX fifo.

This doesn't apply against current code, please check and resend.
diff mbox series

Patch

diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c
index fa0cc08f70ec..637802117c6c 100644
--- a/sound/soc/sh/rz-ssi.c
+++ b/sound/soc/sh/rz-ssi.c
@@ -414,51 +414,48 @@  static int rz_ssi_pio_recv(struct rz_ssi_priv *ssi, struct rz_ssi_stream *strm)
 	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--;
-	}
-
-	/* not enough samples yet */
-	if (samples == 0)
-		return 0;
+	do {
+		/* 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--;
+		}
 
-	/* calculate new buffer index */
-	buf = (u16 *)(runtime->dma_area);
-	buf += strm->buffer_pos * runtime->channels;
+		/* not enough samples yet */
+		if (!samples)
+			break;
 
-	/* Note, only supports 16-bit samples */
-	for (i = 0; i < samples; i++)
-		*buf++ = (u16)(rz_ssi_reg_readl(ssi, SSIFRDR) >> 16);
+		/* calculate new buffer index */
+		buf = (u16 *)runtime->dma_area;
+		buf += strm->buffer_pos * runtime->channels;
 
-	rz_ssi_reg_mask_setl(ssi, SSIFSR, SSIFSR_RDF, 0);
-	rz_ssi_pointer_update(strm, samples / runtime->channels);
+		/* Note, only supports 16-bit samples */
+		for (i = 0; i < samples; i++)
+			*buf++ = (u16)(rz_ssi_reg_readl(ssi, SSIFRDR) >> 16);
 
-	/*
-	 * 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);
+		rz_ssi_reg_mask_setl(ssi, SSIFSR, SSIFSR_RDF, 0);
+		rz_ssi_pointer_update(strm, samples / runtime->channels);
+	} while (!frames_left && fifo_samples >= runtime->channels);
 
 	return 0;
 }