[PATCH 2/3] MTD: OneNAND: Fix loop hang when DMA error at Samsung SoCs

[PATCH 2/3] MTD: OneNAND: Fix loop hang when DMA error at Samsung SoCs

[Kyungmin Park]

From: Kyungmin Park <kyungmin.park@samsung.com>

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 <kyungmin.park@samsung.com>
---
 drivers/mtd/onenand/samsung.c |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/onenand/samsung.c b/drivers/mtd/onenand/samsung.c
index 05329ba..69e48d0 100644
--- a/drivers/mtd/onenand/samsung.c
+++ b/drivers/mtd/onenand/samsung.c
@@ -554,14 +554,13 @@ static int s5pc110_dma_ops(void *dst, void *src, size_t count, int direction)
 
 	do {
 		status = readl(base + S5PC110_DMA_TRANS_STATUS);
+		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));
 
-	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;
-	}
-
 	writel(S5PC110_DMA_TRANS_CMD_TDC, base + S5PC110_DMA_TRANS_CMD);
 
 	return 0;
-- 
1.5.3.3

Re: [PATCH 2/3] MTD: OneNAND: Fix loop hang when DMA error at Samsung SoCs

[Artem Bityutskiy]

On Fri, 2010-08-27 at 11:55 +0900, Kyungmin Park wrote:
> From: Kyungmin Park <kyungmin.park@samsung.com>
> 
> 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 <kyungmin.park@samsung.com>
> ---
>  drivers/mtd/onenand/samsung.c |   11 +++++------
>  1 files changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/onenand/samsung.c b/drivers/mtd/onenand/samsung.c
> index 05329ba..69e48d0 100644
> --- a/drivers/mtd/onenand/samsung.c
> +++ b/drivers/mtd/onenand/samsung.c
> @@ -554,14 +554,13 @@ static int s5pc110_dma_ops(void *dst, void *src, size_t count, int direction)
>  
>  	do {
>  		status = readl(base + S5PC110_DMA_TRANS_STATUS);
> +		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));
>  
> -	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;
> -	}
> -
>  	writel(S5PC110_DMA_TRANS_CMD_TDC, base + S5PC110_DMA_TRANS_CMD);

You shoule also add timeout to the loop. Forever loops are bad. Please,
while you are on it, fix the forever loop by doing something like this:
http://patchwork.ozlabs.org/patch/59180/
I mean, add timeout please.

-- 
Best Regards,
Artem Bityutskiy (Битюцкий Артём)

Re: [PATCH 2/3] MTD: OneNAND: Fix loop hang when DMA error at Samsung SoCs

[Kyungmin Park]

On Mon, Aug 30, 2010 at 9:49 PM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> On Fri, 2010-08-27 at 11:55 +0900, Kyungmin Park wrote:
>> From: Kyungmin Park <kyungmin.park@samsung.com>
>>
>> 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 <kyungmin.park@samsung.com>
>> ---
>>  drivers/mtd/onenand/samsung.c |   11 +++++------
>>  1 files changed, 5 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mtd/onenand/samsung.c b/drivers/mtd/onenand/samsung.c
>> index 05329ba..69e48d0 100644
>> --- a/drivers/mtd/onenand/samsung.c
>> +++ b/drivers/mtd/onenand/samsung.c
>> @@ -554,14 +554,13 @@ static int s5pc110_dma_ops(void *dst, void *src, size_t count, int direction)
>>
>>       do {
>>               status = readl(base + S5PC110_DMA_TRANS_STATUS);
>> +             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));
>>
>> -     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;
>> -     }
>> -
>>       writel(S5PC110_DMA_TRANS_CMD_TDC, base + S5PC110_DMA_TRANS_CMD);
>
> You shoule also add timeout to the loop. Forever loops are bad. Please,
> while you are on it, fix the forever loop by doing something like this:
> http://patchwork.ozlabs.org/patch/59180/
> I mean, add timeout please.

No problem, I will update this patch tomorrow.

Thank you,
Kyungmin Park
>
> --
> Best Regards,
> Artem Bityutskiy (Битюцкий Артём)
>
>
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