[PATCH] mtd: nand: sunxi: Fix ECC strength choice

[PATCH] mtd: nand: sunxi: Fix ECC strength choice

[Miquel Raynal]

When the requested ECC strength does not exactly match the strengths
supported by the ECC engine, the driver is selecting the closest
strength meeting the 'selected_strength > requested_strength'
constraint. Fix the fact that, in this particular case, ecc->strength
value was not updated to match the 'selected_strength'.

For instance, one can encounter this issue when no ECC requirement is
filled in the device tree while the NAND chip minimum requirement is not
a strength/step_size combo natively supported by the ECC engine.

Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
---
 drivers/mtd/nand/sunxi_nand.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/sunxi_nand.c b/drivers/mtd/nand/sunxi_nand.c
index 82244be3e766..958974821582 100644
--- a/drivers/mtd/nand/sunxi_nand.c
+++ b/drivers/mtd/nand/sunxi_nand.c
@@ -1853,8 +1853,14 @@ static int sunxi_nand_hw_common_ecc_ctrl_init(struct mtd_info *mtd,
 
 	/* Add ECC info retrieval from DT */
 	for (i = 0; i < ARRAY_SIZE(strengths); i++) {
-		if (ecc->strength <= strengths[i])
+		if (ecc->strength <= strengths[i]) {
+			/*
+			 * Update ecc->strength value with the actual strength
+			 * that will be used by the ECC engine.
+			 */
+			ecc->strength = strengths[i];
 			break;
+		}
 	}
 
 	if (i >= ARRAY_SIZE(strengths)) {
-- 
2.11.0

[PATCH] mtd: nand: sunxi: Fix ECC strength choice

[Miquel Raynal]

Hello,

On Wed, 24 Jan 2018 23:49:31 +0100
Miquel Raynal <miquel.raynal@free-electrons.com> wrote:

> When the requested ECC strength does not exactly match the strengths
> supported by the ECC engine, the driver is selecting the closest
> strength meeting the 'selected_strength > requested_strength'
> constraint. Fix the fact that, in this particular case, ecc->strength
> value was not updated to match the 'selected_strength'.
> 
> For instance, one can encounter this issue when no ECC requirement is
> filled in the device tree while the NAND chip minimum requirement is not
> a strength/step_size combo natively supported by the ECC engine.
> 

I forgot to add the Fixes/CC tags, but it seems that this problem
has always been out there...

Fixes: 1fef62c1423b ("mtd: nand: add sunxi NAND flash controller
support")
CC: stable at vger.kernel.org

> Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>

I will wait a review before sending a v2.

Thanks,
Miqu?l

[PATCH] mtd: nand: sunxi: Fix ECC strength choice

[Boris Brezillon]

On Wed, 24 Jan 2018 23:59:36 +0100
Miquel Raynal <miquel.raynal@free-electrons.com> wrote:

> Hello,
> 
> On Wed, 24 Jan 2018 23:49:31 +0100
> Miquel Raynal <miquel.raynal@free-electrons.com> wrote:
> 
> > When the requested ECC strength does not exactly match the strengths
> > supported by the ECC engine, the driver is selecting the closest
> > strength meeting the 'selected_strength > requested_strength'
> > constraint. Fix the fact that, in this particular case, ecc->strength
> > value was not updated to match the 'selected_strength'.
> > 
> > For instance, one can encounter this issue when no ECC requirement is
> > filled in the device tree while the NAND chip minimum requirement is not
> > a strength/step_size combo natively supported by the ECC engine.
> >   
> 
> I forgot to add the Fixes/CC tags, but it seems that this problem
> has always been out there...
> 
> Fixes: 1fef62c1423b ("mtd: nand: add sunxi NAND flash controller
> support")
> CC: stable at vger.kernel.org

No need to send a new version. I added the Fixes+stable tags when
applying.

Thanks,

Boris

> 
> > Suggested-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>  
> 
> I will wait a review before sending a v2.
> 
> Thanks,
> Miqu?l