[U-Boot] [PATCH] net: fec: Avoid MX28 bus sync issue

Hector Palacios
2013-07-12T11:37:00Z

Dear Marek,

On 07/12/2013 05:51 AM, Marek Vasut wrote:
> Hi,
>
>> On Thu, Jul 11, 2013 at 8:18 PM, Fabio Estevam <festevam@gmail.com> wrote:
>>> On Thu, Jul 11, 2013 at 8:03 PM, Marek Vasut <marex@denx.de> wrote:
>>>> The MX28 multi-layer AHB bus can be too slow and trigger the
>>>> FEC DMA too early, before all the data hit the DRAM. This patch
>>>> ensures the data are written in the RAM before the DMA starts.
>>>> Please see the comment in the patch for full details.
>>>>
>>>> This patch was produced with an amazing help from Albert Aribaud,
>>>> who pointed out it can possibly be such a bus synchronisation
>>>> issue.
>>>>
>>>> Signed-off-by: Marek Vasut <marex@denx.de>
>>>> Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
>>>> Cc: Fabio Estevam <fabio.estevam@freescale.com>
>>>> Cc: Stefano Babic <sbabic@denx.de>
>>>
>>> Excellent, managed to transfer 90MB via TFTP on mx28evk without a
>>> single timeout.
>>>
>>> Tested-by: Fabio Estevam <fabio.estevam@freescale.com>
>>
>> It's working here too.
>>
>> Tested-by: Alexandre Pereira da Silva <aletes.xgr@gmail.com>
>
> Nice to hear, thank Albert for finding this.

Thanks for sharing.

Unfortunately I'm still seeing non-recoverable timeouts when doing tftp transfers.
Nevertheless, with this patch sometimes I'm able to transfer big files (100MiB)
without problems (I was never able before). So this is a big improvement.
I applied this patch over a v2013.01, does it need any additional patch? I think I saw
one email about flush dcache...

Considering the other guys seem to work without problems I guess this scenario is
specific to my board. I'm using a Micrel KSZ8031RNLI at 50MHz. I always suspect from
the PHY.
I'm disconcerted because usually the timeouts occur after having successfully
downloaded 22 or 24 MiB. Other times it just downloads completely.

In any case, good job!

Best regards,
--
Hector Palacios