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From: Michal Suchanek <hramrach@gmail.com>
Date: Fri, 14 Aug 2015 12:08:00 +0200
Message-ID: <CAOMqctQOU91hbt+2O0qQe3tjMn=3pSYE8E4xPpeS3iGG2A5h8w@mail.gmail.com>
Subject: Re: [PATCH v4 7/7] mtd: spi-nor: add read loop
To: Andrew Murray <amurray@embedded-bits.co.uk>
Cc: Hou Zhiqiang <B48286@freescale.com>, Huang Shijie <shijie.huang@intel.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Brian Norris <computersforpeace@gmail.com>,
        Han Xu <han.xu@freescale.com>,
        =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <zajec5@gmail.com>,
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        Ben Hutchings <ben@decadent.org.uk>, Marek Vasut <marex@denx.de>,
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        =?UTF-8?B?QmVhbiBIdW8g6ZyN5paM5paMLA==?= <beanhuo@micron.com>,
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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