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Re: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request

Started byMichal Suchanek <hramrach@gmail.com>
First post2016-05-18 11:30 +0200
Last post2016-05-18 12:00 +0200
Articles 3 — 2 participants

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  Re: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request Michal Suchanek <hramrach@gmail.com> - 2016-05-18 11:30 +0200
    Re: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read  request Vignesh R <vigneshr@ti.com> - 2016-05-18 11:50 +0200
      Re: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request Michal Suchanek <hramrach@gmail.com> - 2016-05-18 12:00 +0200

#1402829 — Re: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request

FromMichal Suchanek <hramrach@gmail.com>
Date2016-05-18 11:30 +0200
SubjectRe: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request
Message-ID<rA5XH-aM-5@gated-at.bofh.it>
Hello,

On 29 March 2016 at 07:46, Vignesh R <vigneshr@ti.com> wrote:
> Certain SPI controllers may provide accelerated hardware interface to
> read from m25p80 type flash devices in order to provide better read
> performance. SPI core supports such devices with spi_flash_read() API.
> Call spi_flash_read(), if supported, to make use of such interface.
>
> Signed-off-by: Vignesh R <vigneshr@ti.com>
> ---
>
> Resend v5:
> Rebased on top of v4.6-rc1
> v5: http://www.spinics.net/lists/devicetree/msg106696.html
>
>  drivers/mtd/devices/m25p80.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index c9c3b7fa3051..7730e633d7d3 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -131,6 +131,26 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
>         /* convert the dummy cycles to the number of bytes */
>         dummy /= 8;
>
> +       if (spi_flash_read_supported(spi)) {
> +               struct spi_flash_read_message msg;
> +               int ret;
> +
> +               msg.buf = buf;
> +               msg.from = from;
> +               msg.len = len;
> +               msg.read_opcode = nor->read_opcode;
> +               msg.addr_width = nor->addr_width;
> +               msg.dummy_bytes = dummy;
> +               /* TODO: Support other combinations */
> +               msg.opcode_nbits = SPI_NBITS_SINGLE;
> +               msg.addr_nbits = SPI_NBITS_SINGLE;
> +               msg.data_nbits = m25p80_rx_nbits(nor);
> +
> +               ret = spi_flash_read(spi, &msg);
> +               *retlen = msg.retlen;

This is wrong. The previous retlen is never passed into msg so it must
be added and not assigned as is seen a few lines below:

        ret = m.actual_length - m25p_cmdsz(nor) - dummy;
        if (ret < 0)
                return -EIO;
        *retlen += ret;

This interface with odd design and poor documentation will be
hopefully weeded out with
mtd: spi-nor: stop passing around retlen
so there is probably no need to patch this separately.

Thanks

Michal

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#1402843 — Re: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request

FromVignesh R <vigneshr@ti.com>
Date2016-05-18 11:50 +0200
SubjectRe: [RESEND][PATCH] mtd: devices: m25p80: add support for mmap read request
Message-ID<rA6h3-ix-19@gated-at.bofh.it>
In reply to#1402829
Hi,

On 05/18/2016 02:53 PM, Michal Suchanek wrote:
> Hello,
[...]
>>
>> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
>> index c9c3b7fa3051..7730e633d7d3 100644
>> --- a/drivers/mtd/devices/m25p80.c
>> +++ b/drivers/mtd/devices/m25p80.c
>> @@ -131,6 +131,26 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
>>         /* convert the dummy cycles to the number of bytes */
>>         dummy /= 8;
>>
>> +       if (spi_flash_read_supported(spi)) {
>> +               struct spi_flash_read_message msg;
>> +               int ret;
>> +
>> +               msg.buf = buf;
>> +               msg.from = from;
>> +               msg.len = len;
>> +               msg.read_opcode = nor->read_opcode;
>> +               msg.addr_width = nor->addr_width;
>> +               msg.dummy_bytes = dummy;
>> +               /* TODO: Support other combinations */
>> +               msg.opcode_nbits = SPI_NBITS_SINGLE;
>> +               msg.addr_nbits = SPI_NBITS_SINGLE;
>> +               msg.data_nbits = m25p80_rx_nbits(nor);
>> +
>> +               ret = spi_flash_read(spi, &msg);
>> +               *retlen = msg.retlen;
> 
> This is wrong. The previous retlen is never passed into msg so it must
> be added and not assigned as is seen a few lines below:
> 
>         ret = m.actual_length - m25p_cmdsz(nor) - dummy;
>         if (ret < 0)
>                 return -EIO;
>         *retlen += ret;
> 
> This interface with odd design and poor documentation will be
> hopefully weeded out with
> mtd: spi-nor: stop passing around retlen
> so there is probably no need to patch this separately.
> 

This patch was applied by Brian quite sometime back and the v7  of "mtd:
spi-nor: stop passing around retlen" patch takes care of removing the
offending code: https://lkml.org/lkml/2016/5/5/692

-- 
Regards
Vignesh

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#1402846

FromMichal Suchanek <hramrach@gmail.com>
Date2016-05-18 12:00 +0200
Message-ID<rA6qK-mg-15@gated-at.bofh.it>
In reply to#1402843
On 18 May 2016 at 11:39, Vignesh R <vigneshr@ti.com> wrote:
> Hi,
>
> On 05/18/2016 02:53 PM, Michal Suchanek wrote:
>> Hello,
> [...]
>>>
>>> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
>>> index c9c3b7fa3051..7730e633d7d3 100644
>>> --- a/drivers/mtd/devices/m25p80.c
>>> +++ b/drivers/mtd/devices/m25p80.c
>>> @@ -131,6 +131,26 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
>>>         /* convert the dummy cycles to the number of bytes */
>>>         dummy /= 8;
>>>
>>> +       if (spi_flash_read_supported(spi)) {
>>> +               struct spi_flash_read_message msg;
>>> +               int ret;
>>> +
>>> +               msg.buf = buf;
>>> +               msg.from = from;
>>> +               msg.len = len;
>>> +               msg.read_opcode = nor->read_opcode;
>>> +               msg.addr_width = nor->addr_width;
>>> +               msg.dummy_bytes = dummy;
>>> +               /* TODO: Support other combinations */
>>> +               msg.opcode_nbits = SPI_NBITS_SINGLE;
>>> +               msg.addr_nbits = SPI_NBITS_SINGLE;
>>> +               msg.data_nbits = m25p80_rx_nbits(nor);
>>> +
>>> +               ret = spi_flash_read(spi, &msg);
>>> +               *retlen = msg.retlen;
>>
>> This is wrong. The previous retlen is never passed into msg so it must
>> be added and not assigned as is seen a few lines below:
>>
>>         ret = m.actual_length - m25p_cmdsz(nor) - dummy;
>>         if (ret < 0)
>>                 return -EIO;
>>         *retlen += ret;
>>
>> This interface with odd design and poor documentation will be
>> hopefully weeded out with
>> mtd: spi-nor: stop passing around retlen
>> so there is probably no need to patch this separately.
>>
>
> This patch was applied by Brian quite sometime back and the v7  of "mtd:
> spi-nor: stop passing around retlen" patch takes care of removing the
> offending code: https://lkml.org/lkml/2016/5/5/692
>

Yes, I am looking exactly at that patchset but don't see it applied
anywhere yet.

Thanks

Michal

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