Re: RPi4B's DMA11 (DMA4 engine example) vs. xHCI/pcie
Mark Millard via freebsd-arm <[email protected]>
| Newsgroups | gmane.os.freebsd.devel.arm |
|---|---|
| Message-ID | <[email protected]> |
On 2020-Sep-30, at 14:15, Robert Crowston <crowston at protonmail.com> wrote: > Very interesting analysis. Certainly uncovered a few things I wasn't aware of. > > By default sc->sc_bus.dma_bits in xhci_init is 64 bits; I toggle it back to 32 bits in the xhci shim I wrote for the Pi 4. You can see that output in a verbose dmesg. > My biggest worry from all that material, for things as they currently are, is that it appears that FreeBSD could try to use a RPi4B DMA LITE engine but not follow its limitations when doing so. For example, ending up using a smaller size DMA transfer than intended (just 16 bits for size). (Other RPi's might have the same issue?) === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar) _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-arm To unsubscribe, send any mail to "[email protected]"