[PATCH 2/2] spi: dual and quad support(device tree)

[Gupta, Pekon]

> 
> fix one thing in patch:
> commit id:f477b7fb13df2b843997559ff34e87d054ba6538
> 
> change property spi-tx-nbits and spi-rx-nbits to optional.
> If User don't set spi-tx-nbits or spi-rx-nbits, spi device mode
> should be regarded as SINGLE, not return an error.
> 
> Signed-off-by: wangyuhang <wangyuhang2014 at gmail.com>
> ---
>  drivers/spi/spi.c |   68 +++++++++++++++++++++++++--------------------------
> --
>  1 file changed, 32 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index 50f7fc3..46a55f0 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -872,46 +872,42 @@ static void of_register_spi_devices(struct
> spi_master *master)
>  		/* Device DUAL/QUAD mode */
>  		prop = of_get_property(nc, "spi-tx-nbits", &len);
>  		if (!prop || len < sizeof(*prop)) {
> -			dev_err(&master->dev, "%s has no 'spi-tx-nbits'
> property\n",
> -				nc->full_name);
> -			spi_dev_put(spi);
> -			continue;
> -		}
> -		switch (be32_to_cpup(prop)) {
> -		case SPI_NBITS_SINGLE:
> -			break;
> -		case SPI_NBITS_DUAL:
> -			spi->mode |= SPI_TX_DUAL;
> -			break;
> -		case SPI_NBITS_QUAD:
> -			spi->mode |= SPI_TX_QUAD;
> -			break;
> -		default:
> -			dev_err(&master->dev, "spi-tx-nbits value is not
> supported\n");
> -			spi_dev_put(spi);
> -			continue;
> +			/* set tx mode in SINGLE as default */
[Pekon]: I think you should explicitly set, and not trust spi->mode defaults.
	spi->mode |= SPI_TX_SINGLE;

> +		} else {
> +			switch (be32_to_cpup(prop)) {
> +			case SPI_NBITS_SINGLE:
> +				break;
> +			case SPI_NBITS_DUAL:
> +				spi->mode |= SPI_TX_DUAL;
> +				break;
> +			case SPI_NBITS_QUAD:
> +				spi->mode |= SPI_TX_QUAD;
> +				break;

[Pekon]: This is incomplete definition, as indicated in [Patch 1/2] comments.
SPI_NBITS_QUAD does not clearly indicates whether SPI_TX_DUAL mode
is also supported or not. That is..
	spi->mode |= SPI_TX_QUAD;
or
	spi->mode |= SPI_TX_QUAD | SPI_TX_DUAL;


> +			default:
> +				dev_err(&master->dev,
> +					"spi-tx-nbits value is not
> supported\n");
> +				spi_dev_put(spi);
> +				continue;
>  		}
> 
>  		prop = of_get_property(nc, "spi-rx-nbits", &len);
>  		if (!prop || len < sizeof(*prop)) {
> -			dev_err(&master->dev, "%s has no 'spi-rx-nbits'
> property\n",
> -				nc->full_name);
> -			spi_dev_put(spi);
> -			continue;
> -		}
> -		switch (be32_to_cpup(prop)) {
> -		case SPI_NBITS_SINGLE:
> -			break;
> -		case SPI_NBITS_DUAL:
> -			spi->mode |= SPI_RX_DUAL;
> -			break;
> -		case SPI_NBITS_QUAD:
> -			spi->mode |= SPI_RX_QUAD;
> -			break;
> -		default:
> -			dev_err(&master->dev, "spi-rx-nbits value is not
> supported\n");
> -			spi_dev_put(spi);
> -			continue;
> +			/* set rx mode in SINGLE as default */
> +		} else {
> +			switch (be32_to_cpup(prop)) {
> +			case SPI_NBITS_SINGLE:
> +				break;
> +			case SPI_NBITS_DUAL:
> +				spi->mode |= SPI_RX_DUAL;
> +				break;
> +			case SPI_NBITS_QUAD:
> +				spi->mode |= SPI_RX_QUAD;
> +				break;
> +			default:
> +				dev_err(&master->dev,
> +					"spi-rx-nbits value is not
> supported\n");
> +				spi_dev_put(spi);
> +				continue;
>  		}
> 
>  		/* Device speed */
> --
> 1.7.9.5