Re: [RESEND/PATCH 5/6] USB: musb-gadget: complete request only ifdata is transfered over

[Sergei Shtylyov]

Hello.

Felipe Balbi wrote:

> >    If a DMA interrupt comes when the whole transfer is not yet 
> > complete (and
> > other Ming Lei's patches are making this possible),

   Oh, here I mixed some other patch with Ming Lei's ones...

> > it will pass due to the

> than this is the actual problem, no ? If we're using mode1 dma (as we
> are on tx path), we should only get dma interrupt when the whole
> transfer has been completed.

   The Inventra DMA controller has serious DMA length limitation, so the whole 
transfer may take more than one DMA.

> > 'ís_dma' condition above the patched code:

> >                 if (is_dma || request->actual == request->length) {

> > and then it will hit the code sending the final ZLP (above this 
> > patched code too):

> but this was already there before the patch.

   Yes, and here lies the problem.

> >                         /*
> >                          * First, maybe a terminating short packet. 
> > Some DMA
> >                          * engines might handle this by themselves.
> >                          */
> >                         if ((request->zero && request->length
> >                                 && request->length % 
> > musb_ep->packet_sz == 0)
> > #ifdef CONFIG_USB_INVENTRA_DMA
> >                                 || (is_dma && (!dma->desired_mode ||
> >                                         (request->actual &
> >                                                 (musb_ep->packet_sz - 
> > 1))))
> > #endif
> >                         ) {

> > before the transfer is complete while it should only be hit when and 
> > only when
> > the whole transfer is complete. The current code doesn't look correct 
> > as well
> > though, all due to this 'ís_dma' condition. Surely this needs fixing.

> likewise, this was there before the patch. I don't think the real
> problem lies with this patch, it's been there for a while, don't you
> agree ?

   Then what problem this patch fixes, if not this one?

> the problem is not on the extra if () added below the quoted code,
> it's on the quoted code itself, which wasn't changed in any way.

   Let me repeat: in the PIO mode the added check is just duplicate, in the DMA 
mode it's added too late in the code, after ZLP/short packet send is triggered.
We should modify the check at the top of that code instead.

WBR, Sergei
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