[PATCH v2] mtd: m25p80: consider max message size in m25p80_read

[Marek Vasut]

On 10/28/2016 07:58 AM, Heiner Kallweit wrote:
> Consider a message size limit when calculating the maximum amount
> of data that can be read.
> 
> The message size limit has been introduced with 4.9, so cc it
> to stable.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>
> Cc: <stable at vger.kernel.org> # 4.9.x
> ---
> v2:
> - This patch was part of a series and the other patches of the
>   series went into 4.9. It's needed to correctly support
>   reads > 64k on fsl-espi as first user of spi_max_message_size.
>   See commit 02a595d5d6e4 ("spi: fsl-espi: eliminate spi nor
>   flash read loop"). CC it to stable.  

Does this imply that we have to fix every single driver this way ?

> ---
>  drivers/mtd/devices/m25p80.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index 9cf7fcd..16a7df2 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -172,7 +172,8 @@ static ssize_t m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
>  
>  	t[1].rx_buf = buf;
>  	t[1].rx_nbits = m25p80_rx_nbits(nor);
> -	t[1].len = min(len, spi_max_transfer_size(spi));
> +	t[1].len = min3(len, spi_max_transfer_size(spi),
> +			spi_max_message_size(spi) - t[0].len);
>  	spi_message_add_tail(&t[1], &m);
>  
>  	ret = spi_sync(spi, &m);
> 


-- 
Best regards,
Marek Vasut