[PATCH] RFC: mtd/spi-nor: add checking for the spi_nor_read

[Michal Suchanek]

On 31 July 2015 at 14:13, Michal Suchanek <hramrach at gmail.com> wrote:
> Hello,
>
> On 31 July 2015 at 12:35, Hou Zhiqiang <B48286 at freescale.com> wrote:
>> Hi Shijie and Brian,
>>
>> Do you have any comment?
>>
>>> -----Original Message-----
>>> From: Zhiqiang Hou [mailto:B48286 at freescale.com]
>>> Sent: 2015年7月21日 19:57
>>> To: linux-mtd at lists.infradead.org; computersforpeace at gmail.com;
>>> dwmw2 at infradead.org
>>> Cc: Hu Mingkai-B21284; Hou Zhiqiang-B48286
>>> Subject: [PATCH] RFC: mtd/spi-nor: add checking for the spi_nor_read
>>>
>>> From: Hou Zhiqiang <B48286 at freescale.com>
>>>
>>> Compare the var retlen with len to ensure the read operation successful.
>>>
>>> There are some SPI controllers that have a maximum transfer length, e.g.
>>> Freescale eSPI controller is able to transfer 0x10000 Bytes each time.
>>> If the spi_nor_read diliver a transaction length that excced the ability
>>> of the SPI controller, there should be multiple read operation to make
>>> sure this transaction completion.
>>>
>>> Signed-off-by: Hou Zhiqiang <B48286 at freescale.com>
>>> ---
>>>  drivers/mtd/spi-nor/spi-nor.c | 14 ++++++++++++--
>>>  1 file changed, 12 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-
>>> nor.c index fbc5035..ec10cd1 100644
>>> --- a/drivers/mtd/spi-nor/spi-nor.c
>>> +++ b/drivers/mtd/spi-nor/spi-nor.c
>>> @@ -715,6 +715,8 @@ static int spi_nor_read(struct mtd_info *mtd, loff_t
>>> from, size_t len,  {
>>>       struct spi_nor *nor = mtd_to_spi_nor(mtd);
>>>       int ret;
>>> +     size_t cnt = 0;
>>> +     u_char *cur = buf;
>>>
>>>       dev_dbg(nor->dev, "from 0x%08x, len %zd\n", (u32)from, len);
>>>
>>> @@ -722,8 +724,16 @@ 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, retlen, buf);
>>> -
>>> +     *retlen = 0;
>>> +     while (len > 0) {
>>> +             ret = nor->read(nor, from, len, &cnt, cur);
>>> +             if (ret < 0)
>>> +                     break;
>>> +             len -= cnt;
>>> +             cur += cnt;
>>> +             *retlen += cnt;
>>> +             from += cnt;
>>> +     }
>>>       spi_nor_unlock_and_unprep(nor, SPI_NOR_OPS_READ);
>>>       return ret;
>>>  }
>>> --
>>> 2.1.0.27.g96db324
>>
>> Thanks,
>> Zhiqiang
>> ______________________________________________________
>> Linux MTD discussion mailing list
>> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>
>
> It appears that nor->read() always returns 0.
>
> Also see https://www.mail-archive.com/linux-kernel%40vger.kernel.org/msg942729.html
>

Sorry, there is some e-mail thread connectivity problem. This is a
link to the actual patch

http://lists.infradead.org/pipermail/linux-mtd/2015-July/060466.html