[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]: And there please check for spi_master->mode_bits
before setting spi_device->mode.
spi_device->mode should be sub-set of spi_master->mode_bits.
Example: 
switch (be32_to_cpup(prop)) {
	case SPI_NBITS_SINGLE:
		if (spi_master->mode_bits & SPI_TX_SINGLE)
			spi-mode |= SPI_TX_SINGLE;
		else
			pr_err("SPI controller does not support SPI_TX_SINGLE\n");
	break;
	case SPI_NBITS_DUAL:
		if (spi_master->mode_bits & SPI_TX_DUAL)
			spi-mode |= SPI_TX_DUAL;
		else
			pr_err("SPI controller does not support SPI_TX_DUAL\n");
	break;
	case SPI_NBITS_QUAD:
		if (spi_master->mode_bits & SPI_TX_QUAD)
			spi-mode |= SPI_TX_QUAD;
		else
			pr_err("SPI controller does not support SPI_TX_QUAD\n");
	break;
}
This way you will do initial compatibility check between the
device and controller right at the probe, and you don't have
to worry about it later.


> 	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
> 

with regards, pekon