[PATCH V2] SPI: DUAL and QUAD support

[yuhang wang]

Hi


2013/7/29 Trent Piepho <tpiepho at gmail.com>:
> On Sat, Jul 27, 2013 at 2:39 AM, wangyuhang <wangyuhang2014 at gmail.com> wrote:
>> 2:To spidev, in order to backward compatible, still use
>>  SPI_IOC_RD_MODE to deal with user who use <u8 mode>. Add
>>  SPI_IOC_EXTRD_MODE to fix the <u16 mode>. And SPI_IOC_RD_LSB_FIRST
>>  seems a little redundant, so del it.
>
> Your changes to spidev are not backward compatible at all.  You can
> not change the data types in the ioctl and maintain backward
> compatibility.  You can also not delete ioctls!
>
well, please give me some details or specific situations. Why ioctl
can not be changed. The operation that SPI_IOC_RD_LSB_FIRST do can be
done in SPI_IOC_RD_MODE, so I dont think there is any necessary using
SPI_IOC_RD_LSB_FIRST. What you worry about is the user already used
SPI_IOC_RD_LSB_FIRST?

>> @@ -1316,6 +1324,12 @@ int spi_setup(struct spi_device *spi)
>>         /* help drivers fail *cleanly* when they need options
>>          * that aren't supported with their current master
>>          */
>> +       if (((spi->mode >> 8) & 0x03) == 0x03 ||
>> +               ((spi->mode >> 10) & 0x03) == 0x03) {
>> +               dev_err(&spi->dev,
>> +               "setup: can not select dual and quad at the same time\n");
>> +               return -EINVAL;
>> +       }
>
> This code won't work if the constants you added for mode flags change
> value.  More importantly, anyone searching the code for SPI_TX_DUAL,
> etc. won't find this code.
agree, thanks.