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Re: bus_dmamap_sync() for uhci(4) wrote:

> > NVIDIA EHCI has some hardware bug that we don't handle (see PR#37884),
> > though it could be fixed by proper bus_dmatag_subregion(9) and
> > bus_dmamap_sync(9) calls that Manuel is working on.
> Note that we can do bus_dmatag_subregion() without the bus_dmamap_sync()
> calls here, because all DMA memory used by the USB subsystem comes from
> bus_dmamem_alloc(). I'm adding bus_dmamap_sync() calls here because they
> also should cause memory barriers, which are needed to avoid race
> condition between host and controller in the DMA descriptors linked lists
> management.

Do current USB drivers have bus_dmamap_sync(9) calls for data xfers?
Izumi Tsutsui

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