https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=204521
--- Comment #33 from Gary Jennejohn <gljennj...@gmail.com> --- I tried implementing rtsx_xfer_bounce() from the OpenBSD code. OpenBSD uses this function when the upstream code does not pass in a list of DMA scatter-gather addresses. Normally, the SD code in OpenBSD allocates its own DMA buffers and passes them to the driver. Since FreeBSD does not do that - it either uses buffers on the kernel stack or buffers from a struct bio - it seemed logical to me to try rtsx_xfer_bouce(). The DMA transfer raises an interrupt, but the target buffer is always filled with 0s. I'm running out of ideas on how to get DMA to work. If I had a laptop I could tear apart I'd put a logic analyzer on the controller pins and compare the behavior between OpenBSD and FreeBSD. Unfortunately, the laptop I have is a loaner and I can't do that. -- You are receiving this mail because: You are the assignee for the bug. _______________________________________________ freebsd-bugs@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-bugs To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
