Hi,

On Fri, Mar 29, 2019 at 10:02:20AM +0000, Jose Abreu wrote:

On 3/27/2019 8:35 PM, Aaro Koskinen wrote:

quoted

From: Aaro Koskinen <redacted>

We always program the maximum DMA buffer size into the receive descriptor,
although the allocated size may be less. E.g. with the default MTU size
we allocate only 1536 bytes. If somebody sends us a bigger frame, then
memory may get corrupted.

Fix by using exact buffer sizes.

Signed-off-by: Aaro Koskinen <redacted>

So, I'm seeing that the maximum allowed buffer size that can be
put in the descriptor changes between enhanced descriptors to
normal descriptors (8KB vs. 2KB right ?).

There are two size fields, so it's 16KB vs 4 KB.

Shouldn't stmmac_main know about this limit before trying to init
descriptors ?

Yes, and that is not a problem.

We do limit the MTU according to HW version but I would rather
prefer not having to need to calculate min() values in the
descriptor code and just use the value as is ...

I don't think the calculation can be avoided, as the passed value can
be bigger than a single field can hold, or less than the maximum.

A.