linux-kernel - [PATCH] dma: k3dma: Fix non-cyclic mode

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Date:   Mon, 10 Jul 2017 13:53:43 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     Antonio Borneo <borneo.antonio@...il.com>,
        Vinod Koul <vinod.koul@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Zhangfei Gao <zhangfei.gao@...aro.org>,
        dmaengine@...r.kernel.org, John Stultz <john.stultz@...aro.org>
Subject: [PATCH] dma: k3dma: Fix non-cyclic mode

From: Antonio Borneo <borneo.antonio@...il.com>

Commit 36387a2b1f62b5c087c5fe6f0f7b23b94f722ad7 ("k3dma: Fix
memory handling in preparation for cyclic mode") broke the
logic around ds_run/ds_done in case of non-cyclic DMA.

This went unnoticed as the only user of k3dma was the i2s
audio driver, but with a patch set to enable dma on SPI,
the issue cropped up.

This patch resolves the issue by reverting part of the
problematic commit.

This patch has been tested to ensure both audio playback and SPI
works fine using DMA and that no memory leak is present.

Cc: Vinod Koul <vinod.koul@...el.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Zhangfei Gao <zhangfei.gao@...aro.org>
Cc: dmaengine@...r.kernel.org
Signed-off-by: Antonio Borneo <borneo.antonio@...il.com>
[jstultz: Expanded commit message a bit]
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 drivers/dma/k3dma.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/dma/k3dma.c b/drivers/dma/k3dma.c
index 01e25c6..01d2a75 100644
--- a/drivers/dma/k3dma.c
+++ b/drivers/dma/k3dma.c
@@ -223,7 +223,6 @@ static irqreturn_t k3_dma_int_handler(int irq, void *dev_id)
 			if (c && (tc1 & BIT(i))) {
 				spin_lock_irqsave(&c->vc.lock, flags);
 				vchan_cookie_complete(&p->ds_run->vd);
-				WARN_ON_ONCE(p->ds_done);
 				p->ds_done = p->ds_run;
 				p->ds_run = NULL;
 				spin_unlock_irqrestore(&c->vc.lock, flags);
@@ -274,13 +273,14 @@ static int k3_dma_start_txd(struct k3_dma_chan *c)
 		 */
 		list_del(&ds->vd.node);
 
-		WARN_ON_ONCE(c->phy->ds_run);
-		WARN_ON_ONCE(c->phy->ds_done);
 		c->phy->ds_run = ds;
+		c->phy->ds_done = NULL;
 		/* start dma */
 		k3_dma_set_desc(c->phy, &ds->desc_hw[0]);
 		return 0;
 	}
+	c->phy->ds_run = NULL;
+	c->phy->ds_done = NULL;
 	return -EAGAIN;
 }
 
@@ -722,11 +722,7 @@ static int k3_dma_terminate_all(struct dma_chan *chan)
 			k3_dma_free_desc(&p->ds_run->vd);
 			p->ds_run = NULL;
 		}
-		if (p->ds_done) {
-			k3_dma_free_desc(&p->ds_done->vd);
-			p->ds_done = NULL;
-		}
-
+		p->ds_done = NULL;
 	}
 	spin_unlock_irqrestore(&c->vc.lock, flags);
 	vchan_dma_desc_free_list(&c->vc, &head);
-- 
2.7.4