[U-Boot] Issue with USB mass storage (thumb drives)

[Diego]

In data martedì 3 maggio 2016 23:01:10, Marek Vasut ha scritto:
> On 04/29/2016 09:58 AM, Diego wrote:
> > In data venerdì 29 aprile 2016 00:49:22, Marek Vasut ha scritto:
> >> Urgh, so you seem to have third revision of this stick. I have two
> > 
> >> sticks which are exactly the same and work in U-Boot on MX6 wandboard:
> > Hi Marek,
> > 
> > how big is the file you're trying to load?
> >
> > For me it fails for files bigger than 16MB:
>
> Ha ok, I see it now. According to the bus analyzer, the stick Acks long
> block transfer, but then just times out, I guess because it prepares the
> data or something. Just a dummy question, did you try reducing
> USB_MAX_XFER_BLK ? Try with 4096 instead of 65536 , that might work.
> 

Hi Marek,

that was the original argument of my mail thread:
http://lists.denx.de/pipermail/u-boot/2016-April/251799.html
Changing USB_MAX_XFER_BLK from 65535 to 32767 definitely fixed the "EHCI timed 
out on TD".

I was questioning what was the best approach to fix the problem.
It seems that 65536 doesn't work for quite some USB thumb drives. Seeing my 
experience, my coworker's experience, and previous mails in this same thread, 
I'd guess something like 50% or lower work with 65535, while something like 
90% or more work with 32767.
http://lists.denx.de/pipermail/u-boot/2016-February/245893.html

So I see three options:
1) 65535 default with quirk table
2) 32767 default without quirk table
3) 32767 default with quirk table

Personally I think 3) would be the safest solution, but I think 2) would at 
least work for most thumb drives.
As the transfer speed wouldn't be affected much for 32767:
http://lists.denx.de/pipermail/u-boot/2016-February/246267.html
and as the quirk table for 65535 would grow quite a lot with time, I think.

Bests,
Diego