Re: [PATCH 2/2] usb: musb: cppi41: Enable in device-TX mode

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On Tue, Aug 13, 2013 at 4:13 PM, Felipe Balbi <balbi@xxxxxx> wrote:
> On Tue, Aug 13, 2013 at 03:41:01PM -0500, Bin Liu wrote:
>> On Tue, Aug 13, 2013 at 2:21 PM, Felipe Balbi <balbi@xxxxxx> wrote:
>> > On Tue, Aug 13, 2013 at 01:11:47PM -0500, Bin Liu wrote:
>> >> Sebastian,
>> >>
>> >> On Tue, Aug 13, 2013 at 12:38 PM, Sebastian Andrzej Siewior
>> >> <bigeasy@xxxxxxxxxxxxx> wrote:
>> >> > Since the musb-gadget code now calls the dma engine properly it is
>> >> > possible to enable it for the TX path in device mode.
>> >> > AM335x Advisory 1.0.13 says that we may lose the toggle bit on multiple
>> >> > RX transfers. There is a workaround in host mode but none in device mode
>> >> > and therefore RX transfers are disabled.
>> >> 1.0.13 only presents in PG1.0. It has been fixed in PG2.x. Maybe we
>> >> should check for silicon rev here?
>> >
>> > it would be quite difficult to check PG revision from this driver. It
>> > would have to be passed as a flag through DT or something similar.
>>
>> To make the code logic simple, I would think to ignore the rev check
>> and enable CPPI for RX in device mode. I think in theory the
>> controller in device mode will never hit on this hw bug.
>
> this patch is already in my branch going upstream. I think Sebastian has
> a point in leaving this disabled until he knows it's working fine.

Ok. at least we have dma enabled for tx now ;)

>
> --
> balbi
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