[U-Boot] [PATCH v3 1/8] da850: indicate cache usage disable in config file

[Laurence Withers]

On Thu, Aug 18, 2011 at 11:13:19AM -0400, Ben Gardiner wrote:
> I understand that both Laurence and Stefan (cc'd) have confirmed that
> there dcache issues with the EMA; I am assuming that the 'issue'
> results in a delay in tftp'ing...

No; the issue was that packets were being sent on to the wire with incorrect
IP checksums. It twigged that the problem was cache coherency when I put a
full hexdump of each outgoing packet in and suddenly the outbound packets
started being valid.

> Disabling the caches will slow down decompression which will slow down
> boot overall when booting from flash.
> 
> Rather than masking the issue by disabling caches and slowing down
> u-boot for it's users perhaps TI should be fixing the EMAC drivers'
> cache bugs instead?

Indeed, the correct solution is to properly manage the net buffers with
respect to the cache, although I have not attempted that change myself. I
have seen some patches start to flow that make changes in drivers to work
correctly with caches enabled, such as
http://lists.denx.de/pipermail/u-boot/2011-August/098484.html .

Bye for now,
-- 
Laurence Withers, <lwithers at guralp.com>                http://www.guralp.com/
Direct tel:+447753988197 or tel:+443333408643               Software Engineer
General support queries: <support at guralp.com>         CMG-DCM CMG-EAM CMG-NAM