[PATCH v3] ASoC: sh: rz-ssi: Improve error handling in rz_ssi_dma_request function

[PATCH v3] ASoC: sh: rz-ssi: Improve error handling in rz_ssi_dma_request function

[Biju Das]

dma_request_chan() returns error pointer in case of failures, but
the rz_ssi_dma_request() checked for NULL pointer instead.

This patch fixes the issue by checking for ERR_PTR() instead of
NULL and sets the DMA pointers to NULL in error case so that ssi
can fallback to PIO mode.

Fixes: 26ac471c5354 ("ASoC: sh: rz-ssi: Add SSI DMAC support")
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
v2->v3:
 * Added Fixes tag
 * For SSI with with full-duplex transmission and reception, 
   Add support for fallback to PIO mode, if both channels are
   not available.

v1->v2:
 * Replaced IS_ERR_OR_NULL with IS_ERR for error pointer check, as the
   dma_request_chan function never returns NULL pointer for error case.
---
 sound/soc/sh/rz-ssi.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/sound/soc/sh/rz-ssi.c b/sound/soc/sh/rz-ssi.c
index f097c773d413..fa0cc08f70ec 100644
--- a/sound/soc/sh/rz-ssi.c
+++ b/sound/soc/sh/rz-ssi.c
@@ -185,7 +185,7 @@ rz_ssi_stream_get(struct rz_ssi_priv *ssi, struct snd_pcm_substream *substream)
 
 static inline bool rz_ssi_is_dma_enabled(struct rz_ssi_priv *ssi)
 {
-	return (ssi->playback.dma_ch || ssi->capture.dma_ch);
+	return (ssi->playback.dma_ch && (ssi->dma_rt || ssi->capture.dma_ch));
 }
 
 static int rz_ssi_stream_is_valid(struct rz_ssi_priv *ssi,
@@ -676,15 +676,26 @@ static void rz_ssi_release_dma_channels(struct rz_ssi_priv *ssi)
 static int rz_ssi_dma_request(struct rz_ssi_priv *ssi, struct device *dev)
 {
 	ssi->playback.dma_ch = dma_request_chan(dev, "tx");
+	if (IS_ERR(ssi->playback.dma_ch))
+		ssi->playback.dma_ch = NULL;
+
 	ssi->capture.dma_ch = dma_request_chan(dev, "rx");
+	if (IS_ERR(ssi->capture.dma_ch))
+		ssi->capture.dma_ch = NULL;
+
 	if (!ssi->playback.dma_ch && !ssi->capture.dma_ch) {
 		ssi->playback.dma_ch = dma_request_chan(dev, "rt");
-		if (!ssi->playback.dma_ch)
+		if (IS_ERR(ssi->playback.dma_ch)) {
+			ssi->playback.dma_ch = NULL;
 			goto no_dma;
+		}
 
 		ssi->dma_rt = true;
 	}
 
+	if (!rz_ssi_is_dma_enabled(ssi))
+		goto no_dma;
+
 	if (ssi->playback.dma_ch &&
 	    (rz_ssi_dma_slave_config(ssi, ssi->playback.dma_ch, true) < 0))
 		goto no_dma;
-- 
2.17.1

Re: [PATCH v3] ASoC: sh: rz-ssi: Improve error handling in rz_ssi_dma_request function

[Mark Brown]

On Wed, 18 Aug 2021 11:14:50 +0100, Biju Das wrote:
> dma_request_chan() returns error pointer in case of failures, but
> the rz_ssi_dma_request() checked for NULL pointer instead.
> 
> This patch fixes the issue by checking for ERR_PTR() instead of
> NULL and sets the DMA pointers to NULL in error case so that ssi
> can fallback to PIO mode.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: sh: rz-ssi: Improve error handling in rz_ssi_dma_request function
      commit: 4b14f17912052a6963580dfba04781cfe6ccba02

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark