On 08/11/17 11:28, Linus Walleij wrote: > On Fri, Nov 3, 2017 at 2:20 PM, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote: > >> For blk-mq, add support for completing requests directly in the ->done >> callback. That means that error handling and urgent background operations >> must be handled by recovery_work in that case. >> >> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx> > > I tried enabling this on my MMC host (mmci) but I got weird > DMA error messages when I did. > > I guess this has not been tested on a non-DMA-coherent > system? I don't see what DMA-coherence has to do with anything. Possibilities: - DMA unmapping doesn't work in an atomic context - requests' DMA operations have to be synchronized with each other > I think I might be seeing this because the .pre and .post > callbacks need to be strictly sequenced, and this is > maybe not taken into account here? I looked at mmci but that did not seem to be the case. > Isn't there as risk > that the .post callback of the next request is called before > the .post callback of the previous request has returned > for example? Of course, the requests are treated as independent. If the separate DMA operations require synchronization, that is for the host driver to fix.
