From:   Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
To:     Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        Biju Das <biju.das.jz@bp.renesas.com>
Cc:     Pavel Machek <pavel@denx.de>, linux-renesas-soc@vger.kernel.org,
        Prabhakar <prabhakar.csengg@gmail.com>,
        alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/5] ASoC: sh: rz-ssi: Drop calling rz_ssi_pio_recv() recursively
Date:   Mon, 10 Jan 2022 09:47:07 +0000
Message-Id: <20220110094711.8574-2-prabhakar.mahadev-lad.rj@bp.renesas.com>
In-Reply-To: <20220110094711.8574-1-prabhakar.mahadev-lad.rj@bp.renesas.com>
References: <20220110094711.8574-1-prabhakar.mahadev-lad.rj@bp.renesas.com>
Precedence: bulk

Instead of recursively calling rz_ssi_pio_recv() use a while loop
to read the samples from RX fifo.

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>
---
 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) {
+		/* 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);
+		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;
 }
-- 
2.17.1