On 12/04/2017 05:17 PM, Thomas Petazzoni wrote:
The sh_eth driver uses cpu_to_le32() and le32_to_cpu() to manipulate the
fields of the DMA descriptors, making the assumption that the DMA
descriptors are little-endian.
However, testing on the Renesas SH7786 running in big-endian mode reveals
that the DMA descriptors are also big-endian when running big-endian.
Therefore, all the endianness conversion needs to be removed for the sh_eth
driver to work.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> ---
Note: I see that Sergei Shtylyov has done some work around endianness on
this driver back in 2015. I am not sure if it's used on other non-SuperH
platforms in platforms where the CPU might run big-endian but the IP still
be little-endian.
The original Renesas' code assumed that... but the big-endian descriptors
(marked as such) were never used by the arch/sh/ code (and the code wouldn't
work right even if they did!). Therefore I did remove EDMAC_BIG_ENDIAN (and
now EDMAC_LITTLE_ENDIAN can be removed as well).
If this is the case, then we would need a different approach and more
discussion.
No, the ARM platforms sh_eth is used on (mostly R-Car) seem to be
little-endian only.
Therefore, it would be useful to wait for an ACK from Sergei before
applying this patch.
You have it (-:
Acked-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
MBR, Sergei
