RE: Re: [PATCH 2/2 v2] USB: musb: disable double buffering for older

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Hi,
> >> Kroah-Hartman; Subbrathnam, Swaminathan
> >> Subject: Re: [PATCH 2/2 v2] USB: musb: disable double buffering for
> older
> >> RTL versions
> >>
> >> On Tue, Apr 06, 2010 at 01:46:29PM +0200, ext Gadiyar, Anand wrote:
> >> >With g_zero, do you see a hang or do you have data corruption?
> >>
> >> data corruption. But with our internal mode1 changes, we can use double
> >> buffering with rtl1.8 on omap36xx, so at least rtl1.8 can work.
> >
> >Felipe,
> >
> >Have you ensured using either first 8K or second 8K of FIFO space
> >in your double buffering tests for OMAP35x?
> 
> don't remember right now. But I can only remember seeing that errata on
> 36xx not 34xx/35xx. Can you confirm that.

Yes, this issue is valid for OMAP34x/35x also. I have verified double
Buffering on OMAP3EVM with FIFO space of first 8K and didn't see any issue.

Can you test this on your end and confirm ? We would require reverting this
Patch which is already merged in mainline. 

> 
> >I think you are aware of a known issue on OMAP35x where two active
> >endpoints have to use FIFO either in first 8K or next 8K range. I think
> >double
> >buffering data corruption issue is linked to this known issue and can
> >be
> >avoided if we use FIFO space of first 8K or next 8K.
> 
> problem with this is the endpoint limitation. We would have to cope with
> that if we want mode1 + dbuf to work.
We don't have any option due to the known errata on OMAP34x.

Thanks,
Ajay
> 
> --
> balbi
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