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Re: [PATCH v4 7/7] mtd: spi-nor: add read loop

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  Re: [PATCH v4 7/7] mtd: spi-nor: add read loop Andrew Murray <amurray@embedded-bits.co.uk> - 2015-08-14 12:10 +0200
    Re: [PATCH v4 7/7] mtd: spi-nor: add read loop Michal Suchanek <hramrach@gmail.com> - 2015-08-14 12:10 +0200

#1207463 — Re: [PATCH v4 7/7] mtd: spi-nor: add read loop

On 14 August 2015 at 10:23, Michal Suchanek <hramrach@gmail.com> wrote:
> mtdblock and ubi do not handle the situation when read returns less data
> than requested. Loop in spi-nor until buffer is filled or an error is
> returned.
>
> Signed-off-by: Michal Suchanek <hramrach@gmail.com>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 20 ++++++++++++++------
>  1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index e0ae9cf..246fac7 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -738,14 +738,22 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
>         if (ret)
>                 return ret;
>
> -       ret = nor->read(nor, from, len, buf);
> +       while (len) {
> +               ret = nor->read(nor, from, len, buf);
> +               if (ret <= 0)
> +                       goto read_err;
> +
> +               BUG_ON(ret > len);
> +               *retlen += ret;

Is *retlen initialized to 0 anywhere?

Andrew Murray

> +               buf += ret;
> +               from += ret;
> +               len -= ret;
> +       }
> +       ret = 0;
>
> +read_err:
>         spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
> -       if (ret < 0)
> -               return ret;
> -
> -       *retlen += ret;
> -       return 0;
> +       return ret;
>  }
>
>  static int sst_write(struct mtd_info *mtd, loff_t to, size_t len,
> --
> 2.1.4
>
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
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#1207465

On 14 August 2015 at 12:02, Andrew Murray <amurray@embedded-bits.co.uk> wrote:
> On 14 August 2015 at 10:23, Michal Suchanek <hramrach@gmail.com> wrote:
>> mtdblock and ubi do not handle the situation when read returns less data
>> than requested. Loop in spi-nor until buffer is filled or an error is
>> returned.
>>
>> Signed-off-by: Michal Suchanek <hramrach@gmail.com>
>> ---
>>  drivers/mtd/spi-nor/spi-nor.c | 20 ++++++++++++++------
>>  1 file changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
>> index e0ae9cf..246fac7 100644
>> --- a/drivers/mtd/spi-nor/spi-nor.c
>> +++ b/drivers/mtd/spi-nor/spi-nor.c
>> @@ -738,14 +738,22 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t from, size_t len,
>>         if (ret)
>>                 return ret;
>>
>> -       ret = nor->read(nor, from, len, buf);
>> +       while (len) {
>> +               ret = nor->read(nor, from, len, buf);
>> +               if (ret <= 0)
>> +                       goto read_err;
>> +
>> +               BUG_ON(ret > len);
>> +               *retlen += ret;
>
> Is *retlen initialized to 0 anywhere?

It's initialized in mtdcore and passed into mtd->_read.

Yes, the interface is really awkward.

int mtd_read(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
             u_char *buf)
{
        int ret_code;
        *retlen = 0;


Thanks

Michal
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