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MTD: OneNAND: Fix loop hang when DMA error at Samsung SoCs

PATCH In review Kyungmin Park 2 participants 3 messages Aug 30, 2010 – Sep 1, 2010 Memory technology devices (MTD)

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Kyungmin Park

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PATCH v2 1/1 MTD: OneNAND: Fix loop hang when DMA error at Samsung SoCs

From: Kyungmin Park <[email protected]>

When DMA error occurs. it's loop hang since it can't exit the loop. and it's the right DMA handling code as Spec.

Signed-off-by Kyungmin Park <[email protected]>

---
Changelog v1
Add the timeout as Artem comment

 drivers/mtd/onenand/samsung.c |   17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)
drivers/mtd/onenand/samsung.c +10 -7
index d604629..bdaa228 100644
@@ -535,6 +535,7 @@ static int s5pc110_dma_ops(void *dst, void *src, size_t count, int direction)
 {
 	void __iomem *base = onenand->dma_addr;
 	int status;
+	unsigned long timeout;
 
 	writel(src, base + S5PC110_DMA_SRC_ADDR);
 	writel(dst, base + S5PC110_DMA_DST_ADDR);

@@ -552,15 +553,17 @@ static int s5pc110_dma_ops(void *dst, void *src, size_t count, int direction)
 
 	writel(S5PC110_DMA_TRANS_CMD_TR, base + S5PC110_DMA_TRANS_CMD);
 
+	timeout = jiffies + msec_to_jiffies(20);
+
 	do {
 		status = readl(base + S5PC110_DMA_TRANS_STATUS);
-	} while (!(status & S5PC110_DMA_TRANS_STATUS_TD));
-
-	if (status & S5PC110_DMA_TRANS_STATUS_TE) {
-		writel(S5PC110_DMA_TRANS_CMD_TEC, base + S5PC110_DMA_TRANS_CMD);
-		writel(S5PC110_DMA_TRANS_CMD_TDC, base + S5PC110_DMA_TRANS_CMD);
-		return -EIO;
-	}
+		if (status & S5PC110_DMA_TRANS_STATUS_TE) {
+			writel(S5PC110_DMA_TRANS_CMD_TEC,
+					base + S5PC110_DMA_TRANS_CMD);
+			return -EIO;
+		}
+	} while (!(status & S5PC110_DMA_TRANS_STATUS_TD) &&
+		time_before(jiffies, timeout));
 
 	writel(S5PC110_DMA_TRANS_CMD_TDC, base + S5PC110_DMA_TRANS_CMD);
Signature · 1 line
1.5.3.3
#1 lore raw

drivers/mtd/onenand/samsung.c static int s5pc110_dma_ops(void *dst, void *src, size_t count, int direction) · line 556

Quoted 3 lines · Kyungmin Park
drivers/mtd/onenand/samsung.c +1 -0
 	writel(S5PC110_DMA_TRANS_CMD_TR, base + S5PC110_DMA_TRANS_CMD);
 
+	timeout = jiffies + msec_to_jiffies(20);

Are you completely absolutely 100% totally sure 20msecs is enough?

Signature · 2 lines
Best Regards,
Artem Bityutskiy (Битюцкий Артём)
author
#2 lore raw
Quoted 6 lines · Artem Bityutskiy
Quoted 3 lines · Kyungmin Park

      writel(S5PC110_DMA_TRANS_CMD_TR, base + S5PC110_DMA_TRANS_CMD);

+     timeout = jiffies + msec_to_jiffies(20);

Are you completely absolutely 100% totally sure 20msecs is enough?

Actually there's no mention about the timeout time in the Spec. but I tested it both s5pc110 and s5pc210. and working well.

No matter increase the time but I give the 4 chance to the DMA routine. since we got the 5msec times. and in case of s5pc110 it's implemented the HRT. so it's really enough.

If the DMA takes more time than 20msec, it's really slow devices and can't use it. as you know the real transfer size is 2KiB or 4KiB.

Thank you,
Kyungmin Park

Quoted 6 lines

--
Best Regards,
Artem Bityutskiy (Битюцкий Артём)