[U-Boot] [PATCH v2] SPI: Fix 32 bit transfers in mxc_spi.c

[Tom]

Magnus Lilja wrote:
> Commit f9b6a1575d9f1ca192e4cb60e547aa66f08baa3f,  "i.MX31: fix SPI
> driver for shorter than 32 bit" broke 32 bit transfers. This patch
> makes single 32 bit transfer work again.
> 
> Transfer lengths that are known not to work will abort and print
> an error message.
> 
> Tested on i.MX31 Litekit and i.MX31 PDK using 32 bit transfers to
> the MC13783/ATLAS chip (using the 'date' command).
> 
> Signed-off-by: Magnus Lilja <lilja.magnus at gmail.com>
> ---
> 
> As discussed on the mailing list, Guennadi Liakhovetski thinks that
> all transfers > 16 bits are broken. This patch fixes the 32 bit case
> and makes sure the user is notified if a broken bitlength is used.
> 
>  drivers/spi/mxc_spi.c |    9 +++++++++
>  1 files changed, 9 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c
> index fad9840..93c2bd7 100644
> --- a/drivers/spi/mxc_spi.c
> +++ b/drivers/spi/mxc_spi.c
> @@ -131,6 +131,13 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
>  		return 1;
>  	}
>  
> +	/* This driver is currently partly broken, alert the user */
> +	if (bitlen > 16 && bitlen != 32) {

I believe this check can be improved
The transfer loops over 32 bit blks.
so bitlen that are multiples of 32 should work.
so

bitlen != 32

can change to

(bitlen % 32)

Tom

> +		printf("Error: SPI transfer with bitlen=%d is broken.\n",
> +		       bitlen);
> +		return 1;
> +	}
> +
>  	for (i = 0, in_l = (u32 *)din, out_l = (u32 *)dout;
>  	     i < n_blks;
>  	     i++, in_l++, out_l++, bitlen -= 32) {
> @@ -142,6 +149,8 @@ int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
>  				*(u8 *)din = data;
>  			else if (bitlen < 17)
>  				*(u16 *)din = data;
> +			else
> +				*in_l = data;
>  		}
>  	}
>