linux-kernel - [PATCH] drivers: dma: sh: setup

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Message-Id: <20250713182054.795254-1-thomas.andreatta2000@gmail.com>
Date: Sun, 13 Jul 2025 20:20:55 +0200
From: Thomas Andreatta <thomasandreatta2000@...il.com>
To: vkoul@...nel.org
Cc: linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org,
	Thomas Andreatta <thomas.andreatta2000@...il.com>
Subject: [PATCH] drivers: dma: sh: setup_xref error handling

This patch modifies the type of setup_xref from void to int and handles
errors since the function can fail.

`setup_xref` now returns the (eventual) error from
`dmae_set_dmars`|`dmae_set_chcr`, while `shdma_tx_submit` handles the
result, removing the chunks from the queue and marking PM as idle in
case of an error.

First time hittin DMA, if something's off every feedback is welcome.

Signed-off-by: Thomas Andreatta <thomas.andreatta2000@...il.com>
---
 drivers/dma/sh/shdma-base.c | 25 +++++++++++++++++++------
 drivers/dma/sh/shdmac.c     | 17 +++++++++++++----
 include/linux/shdma-base.h  |  2 +-
 3 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index 6b4fce453c85..834741adadaa 100644
--- a/drivers/dma/sh/shdma-base.c
+++ b/drivers/dma/sh/shdma-base.c
@@ -129,12 +129,25 @@ static dma_cookie_t shdma_tx_submit(struct dma_async_tx_descriptor *tx)
 			const struct shdma_ops *ops = sdev->ops;
 			dev_dbg(schan->dev, "Bring up channel %d\n",
 				schan->id);
-			/*
-			 * TODO: .xfer_setup() might fail on some platforms.
-			 * Make it int then, on error remove chunks from the
-			 * queue again
-			 */
-			ops->setup_xfer(schan, schan->slave_id);
+
+			ret = ops->setup_xfer(schan, schan->slave_id);
+			if (ret < 0) {
+				dev_err(schan->dev, "setup_xfer failed: %d\n", ret);
+
+				/* Remove chunks from the queue and mark them as idle */
+				list_for_each_entry_safe(chunk, c, &schan->ld_queue, node) {
+					if (chunk->cookie == cookie) {
+						chunk->mark = DESC_IDLE;
+						list_move(&chunk->node, &schan->ld_free);
+					}
+				}
+
+				schan->pm_state = SHDMA_PM_ESTABLISHED;
+				ret = pm_runtime_put(schan->dev);
+
+				spin_unlock_irq(&schan->chan_lock);
+				return ret;
+			}
 
 			if (schan->pm_state == SHDMA_PM_PENDING)
 				shdma_chan_xfer_ld_queue(schan);
diff --git a/drivers/dma/sh/shdmac.c b/drivers/dma/sh/shdmac.c
index 093e449e19ee..603e15102e45 100644
--- a/drivers/dma/sh/shdmac.c
+++ b/drivers/dma/sh/shdmac.c
@@ -300,21 +300,30 @@ static bool sh_dmae_channel_busy(struct shdma_chan *schan)
 	return dmae_is_busy(sh_chan);
 }
 
-static void sh_dmae_setup_xfer(struct shdma_chan *schan,
-			       int slave_id)
+static int sh_dmae_setup_xfer(struct shdma_chan *schan, int slave_id)
 {
 	struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
 						    shdma_chan);
 
+	int ret = 0;
 	if (slave_id >= 0) {
 		const struct sh_dmae_slave_config *cfg =
 			sh_chan->config;
 
-		dmae_set_dmars(sh_chan, cfg->mid_rid);
-		dmae_set_chcr(sh_chan, cfg->chcr);
+		ret = dmae_set_dmars(sh_chan, cfg->mid_rid);
+		if (ret < 0)
+			goto END;
+
+		ret = dmae_set_chcr(sh_chan, cfg->chcr);
+		if (ret < 0)
+			goto END;
+
 	} else {
 		dmae_init(sh_chan);
 	}
+
+END:
+	return ret;
 }
 
 /*
diff --git a/include/linux/shdma-base.h b/include/linux/shdma-base.h
index 6dfd05ef5c2d..03ba4dab2ef7 100644
--- a/include/linux/shdma-base.h
+++ b/include/linux/shdma-base.h
@@ -96,7 +96,7 @@ struct shdma_ops {
 	int (*desc_setup)(struct shdma_chan *, struct shdma_desc *,
 			  dma_addr_t, dma_addr_t, size_t *);
 	int (*set_slave)(struct shdma_chan *, int, dma_addr_t, bool);
-	void (*setup_xfer)(struct shdma_chan *, int);
+	int (*setup_xfer)(struct shdma_chan *, int);
 	void (*start_xfer)(struct shdma_chan *, struct shdma_desc *);
 	struct shdma_desc *(*embedded_desc)(void *, int);
 	bool (*chan_irq)(struct shdma_chan *, int);
-- 
2.34.1