[no subject]

> 
>> when read or written in Double Transfer Rate (DTR) mode compared to
>> Single Transfer Rate (STR) mode. If one writes D0 D1 D2 D3 bytes using
>> 1-1-1 mode, and uses 8D-8D-8D SPI mode for reading, it will read back
>> D1 D0 D3 D2. Swapping the bytes is a bad design decision because this may
>> introduce some endianness problems. It can affect the boot sequence if the
>> entire boot sequence is not handled in either 8D-8D-8D mode or 1-1-1 mode.
>> Fortunately there are controllers that can swap back the bytes at runtime,
>> fixing the endiannesses. Provide a way for the upper layers to specify the
>> byte order in DTR mode.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx>
>> ---
>>  include/linux/spi/spi-mem.h | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
>> index 85e2ff7b840d..e1878417420c 100644
>> --- a/include/linux/spi/spi-mem.h
>> +++ b/include/linux/spi/spi-mem.h
>> @@ -89,6 +89,8 @@ enum spi_mem_data_dir {
>>   * @dummy.dtr: whether the dummy bytes should be sent in DTR mode or not
>>   * @data.buswidth: number of IO lanes used to send/receive the data
>>   * @data.dtr: whether the data should be sent in DTR mode or not
>> + * @data.dtr_bswap16: whether the byte order of 16-bit words is swapped when
>> + *                 read or written in DTR mode compared to STR mode.
>>   * @data.dir: direction of the transfer
>>   * @data.nbytes: number of data bytes to send/receive. Can be zero if the
>>   *            operation does not involve transferring data
>> @@ -119,6 +121,7 @@ struct spi_mem_op {
>>       struct {
>>               u8 buswidth;
>>               u8 dtr : 1;
>> +             u8 dtr_bswap16 : 1;

but I would keep this name here as it is, without prepending octal.

> 
> You also need to add this capability to spi_controller_mem_caps and
> update spi_mem_default_supports_op() to check for it.

sure, will do.

Thanks!
ta
> 
>>               enum spi_mem_data_dir dir;
>>               unsigned int nbytes;
>>               union {
>> --
>> 2.25.1
>>
> 
> --
> Regards,
> Pratyush Yadav
> Texas Instruments Inc.