[U-Boot] [PATCH V3 05/10] fat: ff: read max contiguous file data

[Stephen Warren]

On 10/20/2015 01:10 PM, Tom Rini wrote:
> On Tue, Oct 20, 2015 at 12:57:32PM -0600, Stephen Warren wrote:
>> On 10/02/2015 12:06 AM, Stephen Warren wrote:
>>> Enhance f_read() to find the maximum contiguous set of clusters to read,
>>> and read it all at once (which is fast) rather one by one (which is
>>> slow).
>>
>> Hmm. I had hoped that the author of ff.c would accept this patch
>> upstream, so we could pick up a later upstream version that included
>> this patch. However, it seems the author of ff.c has a policy of not
>> accepting outside contributions:
>>
>> http://elm-chan.org/fsw/ff/bd/?show=2472
>> (That's a link to the author's reply to my patch, on the forum
>> system associated with his/her SW)
>
> The bit about the license is at
> http://elm-chan.org/fsw/ff/en/appnote.html#license
>
>> I wonder how much of a liability incorporating ff.c into U-Boot will
>> be, if we can't ever get any fixes merged upstream. Perhaps we just
>> fork it, although I had hoped we'd be able to keep picking up new
>> versions.
>
> Arg, that really does take away one of the potential nice features.  I
> guess, sadly, at this point I'd rather stick with the version we have
> unless you want to deal with re-syncing their releases but still
> effectively doing a fork (so that we can also make use of caches which I
> think you said before you thought might be part of the performance
> problem.

FWIW, the caching (of FAT bitmap, not CPU memory) turned out not to be 
an issue at all; it was just my wild conjecture before I'd investigated 
the read performance issues.