[U-Boot] [PATCH V3] net: fec_mxc: allow use with cache enabled

[Marek Vasut <marex@denx.de>]

Dear Eric Nelson,

> 	ensure that transmit and receive buffers are cache-line aligned
>         invalidate cache for each packet as received
> 	update receive buffer descriptors one cache line at a time
>         flush cache before transmitting
> 
> Original patch by Marek:
> 	http://lists.denx.de/pipermail/u-boot/2012-February/117695.html
> 
> Signed-off-by: Eric Nelson <eric.nelson@boundarydevices.com>
> 
> ---
> V2 addresses some concerns from the ML:
> 	- Use readl()/writel() instead of mapped data structure
> 	  accesses
> 	- Wrong comment style
> 	- &rbd_base[0] == rbd_base
> 	removed 'volatile' from fec_send().
> 
> V3 updates from ML (and Marek):
> 	consolidated CONFIG_FEC_DATA_ALIGNMENT and CONFIG_FEC_DESC_ALIGNMENT
> 	added cache flushes after initialization of TBD/RBD
> 
>  drivers/net/fec_mxc.c |  265
> +++++++++++++++++++++++++++++++++++-------------- drivers/net/fec_mxc.h | 
>  19 +----
>  2 files changed, 189 insertions(+), 95 deletions(-)
> 
> diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c
> index 1fdd071..94a3927 100644
> --- a/drivers/net/fec_mxc.c
> +++ b/drivers/net/fec_mxc.c
> @@ -50,6 +50,24 @@ DECLARE_GLOBAL_DATA_PTR;
>  #define	CONFIG_FEC_MXC_SWAP_PACKET
>  #endif
> 
> +#if ARCH_DMA_MINALIGN > CONFIG_SYS_CACHELINE_SIZE
> +#define CONFIG_FEC_ALIGN ARCH_DMA_MINALIGN
> +#else
> +#define CONFIG_FEC_ALIGN CONFIG_SYS_CACHELINE_SIZE
> +#endif

Check PPC and let's go with ARCH_DMA_MINALIGN

> +
> +#define RXDESC_PER_CACHELINE	(CONFIG_FEC_ALIGN/sizeof(struct fec_bd))
> +
> +/* Check various alignment issues at compile time */
> +#if ((CONFIG_FEC_ALIGN < 16) || (CONFIG_FEC_ALIGN % 16 != 0))
> +#error	"CONFIG_FEC_ALIGN must be multiple of 16!"
> +#endif
> +
> +#if ((PKTALIGN < CONFIG_FEC_ALIGN) || \
> +	(PKTALIGN % CONFIG_FEC_ALIGN != 0))
> +#error	"PKTALIGN must be multiple of CONFIG_FEC_ALIGN!"
> +#endif

We should keep these checks in case some obscure platform appears.

Otherwise, we're almost there Eric! Great work !!

Best regards,
Marek Vasut