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

[Netagunte, Nagabhushana]

Gentlemen,

We will address cache coherency issues soon after these patches.
Earlier also, chache was disabled. Only due to new cache management
Framework which was added recently, it is explicitly needed to be 
Indicated to turn off cache. 

Since fixing the cache coherency issues with EMAC will take some time,
I want this patch to go in mainline so that issue doesn't crop up for
People who use u-boot.

Regards,
Nag
-----Original Message-----
From: Laurence Withers [mailto:lwithers at guralp.com] 
Sent: Thursday, August 18, 2011 8:50 PM
To: Ben Gardiner
Cc: Netagunte, Nagabhushana; u-boot at lists.denx.de; Rajashekhara, Sudhakar; Hadli, Manjunath; Stefan Roese
Subject: Re: [U-Boot] [PATCH v3 1/8] da850: indicate cache usage disable in config file

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