mtd: spi-nor: Fix the number of bytes for the dummy cycles

[PATCH] mtd: spi-nor: Fix the number of bytes for the dummy cycles

Posted by Allen-KH Cheng 1 year, 10 months ago

The number of bytes used by spi_nor_spimem_check_readop() may be
incorrect for the dummy cycles. Since nor->read_dummy is not initialized
before spi_nor_spimem_adjust_hwcaps().

We use both mode and wait state clock cycles instead of nor->read_dummy.

Fixes: 0e30f47232ab ("mtd: spi-nor: add support for DTR protocol")
Co-developed-by: Bayi Cheng <bayi.cheng@mediatek.com>
Signed-off-by: Bayi Cheng <bayi.cheng@mediatek.com>
Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
---
 drivers/mtd/spi-nor/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index 6c921eb3fadb..8b9c318a0ad4 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -1914,7 +1914,8 @@ static int spi_nor_spimem_check_readop(struct spi_nor *nor,
 	spi_nor_spimem_setup_op(nor, &op, read->proto);
 
 	/* convert the dummy cycles to the number of bytes */
-	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
+	op.dummy.nbytes = (read->num_mode_clocks + read->num_wait_states) *
+			  op.dummy.buswidth / 8;
 	if (spi_nor_protocol_is_dtr(nor->read_proto))
 		op.dummy.nbytes *= 2;
 
-- 
2.18.0

Re: [PATCH] mtd: spi-nor: Fix the number of bytes for the dummy cycles

Posted by Tudor Ambarus 1 year, 10 months ago

On Mon, 31 Oct 2022 20:46:33 +0800, Allen-KH Cheng wrote:
> The number of bytes used by spi_nor_spimem_check_readop() may be
> incorrect for the dummy cycles. Since nor->read_dummy is not initialized
> before spi_nor_spimem_adjust_hwcaps().
> 
> We use both mode and wait state clock cycles instead of nor->read_dummy.
> 
> 
> [...]

Applied to spi-nor/next, thanks!

[1/1] mtd: spi-nor: Fix the number of bytes for the dummy cycles
      https://git.kernel.org/mtd/c/fdc20370d93e

Best regards,
-- 
Tudor Ambarus <tudor.ambarus@microchip.com>

Re: [PATCH] mtd: spi-nor: Fix the number of bytes for the dummy cycles

Posted by Pratyush Yadav 1 year, 10 months ago

On 31/10/22 08:46PM, Allen-KH Cheng wrote:
> The number of bytes used by spi_nor_spimem_check_readop() may be
> incorrect for the dummy cycles. Since nor->read_dummy is not initialized
> before spi_nor_spimem_adjust_hwcaps().
> 
> We use both mode and wait state clock cycles instead of nor->read_dummy.
> 
> Fixes: 0e30f47232ab ("mtd: spi-nor: add support for DTR protocol")
> Co-developed-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
> ---
>  drivers/mtd/spi-nor/core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 6c921eb3fadb..8b9c318a0ad4 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1914,7 +1914,8 @@ static int spi_nor_spimem_check_readop(struct spi_nor *nor,
>  	spi_nor_spimem_setup_op(nor, &op, read->proto);
>  
>  	/* convert the dummy cycles to the number of bytes */
> -	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
> +	op.dummy.nbytes = (read->num_mode_clocks + read->num_wait_states) *
> +			  op.dummy.buswidth / 8;

Good catch!

Reviewed-by: Pratyush Yadav <pratyush@kernel.org>

>  	if (spi_nor_protocol_is_dtr(nor->read_proto))
>  		op.dummy.nbytes *= 2;
>  
> -- 
> 2.18.0
> 

-- 
Regards,
Pratyush Yadav

Re: [PATCH] mtd: spi-nor: Fix the number of bytes for the dummy cycles

Posted by AngeloGioacchino Del Regno 1 year, 10 months ago

Il 31/10/22 13:46, Allen-KH Cheng ha scritto:
> The number of bytes used by spi_nor_spimem_check_readop() may be
> incorrect for the dummy cycles. Since nor->read_dummy is not initialized
> before spi_nor_spimem_adjust_hwcaps().
> 
> We use both mode and wait state clock cycles instead of nor->read_dummy.
> 
> Fixes: 0e30f47232ab ("mtd: spi-nor: add support for DTR protocol")
> Co-developed-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
> Tested-by: Dhruva Gole <d-gole@ti.com>

On MT8195 Tomato Chromebook:
Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Re: [EXTERNAL] [PATCH] mtd: spi-nor: Fix the number of bytes for the dummy cycles

Posted by Dhruva Gole 1 year, 10 months ago

On 31/10/22 18:16, Allen-KH Cheng wrote:
> The number of bytes used by spi_nor_spimem_check_readop() may be
> incorrect for the dummy cycles. Since nor->read_dummy is not initialized
> before spi_nor_spimem_adjust_hwcaps().
>
> We use both mode and wait state clock cycles instead of nor->read_dummy.
>
> Fixes: 0e30f47232ab ("mtd: spi-nor: add support for DTR protocol")
> Co-developed-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
> ---

Tested-by: Dhruva Gole <d-gole@ti.com>

>   drivers/mtd/spi-nor/core.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 6c921eb3fadb..8b9c318a0ad4 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1914,7 +1914,8 @@ static int spi_nor_spimem_check_readop(struct spi_nor *nor,
>   	spi_nor_spimem_setup_op(nor, &op, read->proto);
>   
>   	/* convert the dummy cycles to the number of bytes */
> -	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
> +	op.dummy.nbytes = (read->num_mode_clocks + read->num_wait_states) *
> +			  op.dummy.buswidth / 8;
>   	if (spi_nor_protocol_is_dtr(nor->read_proto))
>   		op.dummy.nbytes *= 2;
>   
Tested on my AM625 SK EVM having spi nor flash and no obvious 
regressions observed :)

-- 
Best regards,
Dhruva Gole
Texas Instruments Incorporated