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

[Stephen Warren]

On 10/20/15 1:10 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.
> 
> Or we take a look at borrowing the kernel's code, similar to how we
> leverage UBIFS today.
> 
> Regardless, thanks for the time you've already put in on this!

If anyone is still interested in replacing the FAT code, I just noticed 
that FreeRTOS has been relicensed to MIT along with some/all of its 
extensions, including the FAT code:

https://www.freertos.org/FreeRTOS-Plus/FreeRTOS_Plus_FAT/index.html

I'd assume that code is reasonably well maintained and 
embedded-suitable. I have not investigated:

- If it has the same "no contributions" issue that FF had.
- If it's modular enough to plug into other hosts besides FreeRTOS.
- What its performance is like.