Hi Tom,
On Fri, Jun 15, 2012 at 8:50 PM, Tom Rini <tr...@ti.com> wrote:
> On 06/15/2012 08:18 AM, R, Sricharan wrote:
>> Hi,
>> [snip..]
>>>>>> If it is a problem with unaligned regions, then that is the only
>>>>>> thing to be fixed
>>>>>> right ?. Just trying to understand why this change is required ?
>>>>>
>>>>> The problem is that within the USB/network/filesystem stacks we have a
>>>>> lot of not cache safe alignments apparently. Without this every '#' of
>>>>> a tftp gives a screen full of error printfs. So tftp'ing a kernel takes
>>>>> minutes, not seconds, to complete.
>>>>>
>>>> Ok,but when buffers are not aligned
>>>> isn't that you are going to have coherency problems ?
>>>
>>> Exactly. USB requires dcache to be turned off today. With it turned
>>> off it spams these messages making tftp to an aligned address take
>>> minutes because the console is busy printing all of these messages about
>>> flushes it didn't need to do. The alternative is to build
>>> omap4/omap5/etc with dcache disabled or USB disabled.
>>>
>> Ok, but who is calling cache maintenance in your case after
>> turning off caches ?
>
> The USB stack currently.
Ok, in that case if
1) Alignment issue has to be fixed USB stack, (or)
2) Better to turn off caches when say USB-EHCI is enabled ?
(or)
3) Turn of caches until cache library is fixed so that
we will not require any maintenance after turning it off.
( I will work on this some time, this week)
I am not sure which one to do, but definitely we should not
prevent it from executing as in the above patch. This may
lead to other issues.
Thanks,
Sricharan
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot
