[PATCH] mtd: spi-nor: Fix the write Status Register on micron flashes

[PATCH] mtd: spi-nor: Fix the write Status Register on micron flashes

[Tudor.Ambarus]

From: Tudor Ambarus <tudor.ambarus@microchip.com>

Micron flashes do not support 16 bit writes on the Status Register.
According to micron datasheets, when using the Write Status Register
(01h) command, the chip select should be driven LOW and held LOW until
the eighth bit of the last data byte has been latched in, after which
it must be driven HIGH. If CS is not driven HIGH, the command is not
executed, flag status register error bits are not set, and the write enable
latch remains set to 1. This fixes the lock operations on micron flashes.

Reported-by: John Garry <john.garry@huawei.com>
Fixes: 39d1e3340c73 ("mtd: spi-nor: Fix clearing of QE bit on lock()/unlock()")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 drivers/mtd/spi-nor/spi-nor.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index f1490c7b5cb9..7e41493f69d8 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -4607,6 +4607,7 @@ static void sst_set_default_init(struct spi_nor *nor)
 static void st_micron_set_default_init(struct spi_nor *nor)
 {
 	nor->flags |= SNOR_F_HAS_LOCK;
+	nor->flags &= ~SNOR_F_HAS_16BIT_SR;
 	nor->params.quad_enable = NULL;
 	nor->params.set_4byte = st_micron_set_4byte;
 }
-- 
2.14.5

[PATCH v2] mtd: spi-nor: Fix the writing of the Status Register on micron flashes

[Tudor.Ambarus]

From: Tudor Ambarus <tudor.ambarus@microchip.com>

Micron flashes do not support 16 bit writes on the Status Register.
According to micron datasheets, when using the Write Status Register
(01h) command, the chip select should be driven LOW and held LOW until
the eighth bit of the last data byte has been latched in, after which
it must be driven HIGH. If CS is not driven HIGH, the command is not
executed, flag status register error bits are not set, and the write enable
latch remains set to 1. This fixes the lock operations on micron flashes.

Reported-by: John Garry <john.garry@huawei.com>
Fixes: 39d1e3340c73 ("mtd: spi-nor: Fix clearing of QE bit on lock()/unlock()")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
v2: reword commit subject

 drivers/mtd/spi-nor/spi-nor.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index f1490c7b5cb9..7e41493f69d8 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -4607,6 +4607,7 @@ static void sst_set_default_init(struct spi_nor *nor)
 static void st_micron_set_default_init(struct spi_nor *nor)
 {
 	nor->flags |= SNOR_F_HAS_LOCK;
+	nor->flags &= ~SNOR_F_HAS_16BIT_SR;
 	nor->params.quad_enable = NULL;
 	nor->params.set_4byte = st_micron_set_4byte;
 }
-- 
2.14.5

Re: [PATCH v2] mtd: spi-nor: Fix the writing of the Status Register on micron flashes

[John Garry]

On 03/12/2019 14:50, Tudor.Ambarus@microchip.com wrote:
> From: Tudor Ambarus <tudor.ambarus@microchip.com>
> 
> Micron flashes do not support 16 bit writes on the Status Register.
> According to micron datasheets, when using the Write Status Register
> (01h) command, the chip select should be driven LOW and held LOW until
> the eighth bit of the last data byte has been latched in, after which
> it must be driven HIGH. If CS is not driven HIGH, the command is not
> executed, flag status register error bits are not set, and the write enable
> latch remains set to 1. This fixes the lock operations on micron flashes.
> 
> Reported-by: John Garry <john.garry@huawei.com>
> Fixes: 39d1e3340c73 ("mtd: spi-nor: Fix clearing of QE bit on lock()/unlock()")
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

Thanks,

Tested-by: John Garry <john.garry@huawei.com>

> ---
> v2: reword commit subject
> 
>   drivers/mtd/spi-nor/spi-nor.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index f1490c7b5cb9..7e41493f69d8 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -4607,6 +4607,7 @@ static void sst_set_default_init(struct spi_nor *nor)
>   static void st_micron_set_default_init(struct spi_nor *nor)
>   {
>   	nor->flags |= SNOR_F_HAS_LOCK;
> +	nor->flags &= ~SNOR_F_HAS_16BIT_SR;
>   	nor->params.quad_enable = NULL;
>   	nor->params.set_4byte = st_micron_set_4byte;
>   }
> 

Re: [PATCH v2] mtd: spi-nor: Fix the writing of the Status Register on micron flashes

[Miquel Raynal]

On Tue, 2019-12-03 at 14:50:01 UTC,  wrote:
> From: Tudor Ambarus <tudor.ambarus@microchip.com>
> 
> Micron flashes do not support 16 bit writes on the Status Register.
> According to micron datasheets, when using the Write Status Register
> (01h) command, the chip select should be driven LOW and held LOW until
> the eighth bit of the last data byte has been latched in, after which
> it must be driven HIGH. If CS is not driven HIGH, the command is not
> executed, flag status register error bits are not set, and the write enable
> latch remains set to 1. This fixes the lock operations on micron flashes.
> 
> Reported-by: John Garry <john.garry@huawei.com>
> Fixes: 39d1e3340c73 ("mtd: spi-nor: Fix clearing of QE bit on lock()/unlock()")
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> Tested-by: John Garry <john.garry@huawei.com>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks.

Miquel