[PATCH V2] SPI: DUAL and QUAD support

[Trent Piepho]

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!


> @@ -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.