Re: commit ef11982dd7a657512c362242508bb4021e0d67b6 breaks musb

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On Wed, Mar 11, 2015 at 09:03:54AM +0100, Sebastian Andrzej Siewior wrote:
> On 03/10/2015 10:22 PM, Felipe Balbi wrote:
> > On Thu, Mar 05, 2015 at 12:25:48PM +0530, Amit Virdi wrote:
> >> +cc Sebastian, Alan Stern
> >>
> >> Hello Felipe,
> >>
> >> On 2/28/2015 3:18 AM, Felipe Balbi wrote:
> >>> Hi Amit,
> >>>
> >>> commit ef11982dd7a657512c362242508bb4021e0d67b6 (Add support for
> >>> interrupt EP) actually broke testusb for MUSB when MUSB is the gadget.
> >>>
> >>> The reason is that we're requesting an endpoint with a 64-byte FIFO, but
> >>> later deciding to use the same endpoint with wMaxPacketSize set to 1024
> >>> and MUSB errors out because the endpoint was selected for 64-byte only.
> >>>
> >>> This only happens when trying to set alternate setting 2 and it's pretty
> >>> easy to trigger.
> >>>
> >>
> >> This issue was brought up earlier by Sebastian. He even submitted a patch
> >> for the same and there were discussions over it.
> >> http://www.spinics.net/lists/linux-usb/msg117962.html
> >>
> >> However, things were never concluded. Using module parameters should get it
> >> working but that isn't a clean solution.
> >>
> >> What do you suggest?
> > 
> > allocate endpoints based on largest wMaxPacketSize ? If we have more
> > FIFO space than needed, that's not a problem. The problem is when we
> > allocate a FIFO which is not large enough.
> 
> Please either revert the patch that broke things or apply mine until
> the whole endpoint allocations is reworked so this is not an issue
> anymore.

I'll apply your patch, but add a few comments as to why we're doing it
that way.

-- 
balbi

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