[U-Boot] [PATCH 6/9] CACHE: nand read/write: Test if start address is aligned

[Aneesh V]

On 06/24/2012 05:17 PM, Marek Vasut wrote:
> This prevents the scenario where data cache is on and the
> device uses DMA to deploy data. In that case, it might not
> be possible to flush/invalidate data to RAM properly. The
> other option is to use bounce buffer, but that involves a
> lot of copying and therefore degrades performance rapidly.
> Therefore disallow this possibility of unaligned load address
> altogether if data cache is on.
>
> Signed-off-by: Marek Vasut<marex at denx.de>
> Cc: Scott Wood<scottwood at freescale.com>
> ---
>   common/cmd_nand.c |    9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/common/cmd_nand.c b/common/cmd_nand.c
> index a91ccf4..122a91c 100644
> --- a/common/cmd_nand.c
> +++ b/common/cmd_nand.c
> @@ -609,6 +609,8 @@ int do_nand(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
>   			goto usage;
>
>   		addr = (ulong)simple_strtoul(argv[2], NULL, 16);
> +		if (!cacheline_aligned(addr))
> +			return 1;

You need to check the end address too. Also, I agree with Scott that
that this is an un-justifiable restriction on cache-coherent
architectures. IMO, such checks should be done in platform specific
code where the DMA is being attempted.

best regards,
Aneesh