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SubjectRe: [PATCH 1/2] mtd: spi-nor: rework spi nor read and write.
Date
On Tuesday, July 28, 2015 at 11:23:02 AM, Michal Suchanek wrote:
> The spi_nor read and write functions pass thru the mtd retlen to the
> chip-specific read and write function. This makes it difficult to check
> for errors in read and write functions and these errors are not checked.
> This leads to silent data corruption.
>
> This patch styles the chip-specific read and write function as unix
> read(2) and write(2) and updates the retlen in the spi-nor generic driver.
>
> This also makes it possible to check for write errors.
> When pl330 fails to transfer the flash data over SPI I get I/O error
> instead of 4M of zeroes.
>
> I do not have sst and fsl hardware to test with.
>
> Signed-off-by: Michal Suchanek <hramrach@gmail.com>
> ---
> drivers/mtd/devices/m25p80.c | 33 ++++++++++++++---------
> drivers/mtd/spi-nor/fsl-quadspi.c | 29 ++++++++++----------
> drivers/mtd/spi-nor/spi-nor.c | 57
> ++++++++++++++++++++++++++++----------- include/linux/mtd/spi-nor.h
> | 8 +++---
> 4 files changed, 81 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index d313f948b..d8f064b 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -75,14 +75,15 @@ static int m25p80_write_reg(struct spi_nor *nor, u8
> opcode, u8 *buf, int len, return spi_write(spi, flash->command, len + 1);
> }
>
> -static void m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
> - size_t *retlen, const u_char *buf)
> +static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
> + const u_char *buf)
> {
> struct m25p *flash = nor->priv;
> struct spi_device *spi = flash->spi;
> struct spi_transfer t[2] = {};
> struct spi_message m;
> int cmd_sz = m25p_cmdsz(nor);
> + ssize_t ret;
>
> spi_message_init(&m);
>
> @@ -100,9 +101,14 @@ static void m25p80_write(struct spi_nor *nor, loff_t
> to, size_t len, t[1].len = len;
> spi_message_add_tail(&t[1], &m);
>
> - spi_sync(spi, &m);
> + ret = spi_sync(spi, &m);
> + if (ret)
> + return ret;
>
> - *retlen += m.actual_length - cmd_sz;
> + ret = m.actual_length - cmd_sz;
> + if (ret < 0)
> + return -EIO;
> + return ret;

I'd prefer to just add the return value and keep the retlen to keep error
codes and transfer length separate.

btw. you change the transfer length from unsigned to signed type -- long
transfer might get interpreted as an error.

[...]


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