08.05.2019 12:24, Jon Hunter пишет: > > On 05/05/2019 19:12, Dmitry Osipenko wrote: >> The DMA_PREP_INTERRUPT flag means that descriptor's callback should be >> invoked upon transfer completion and that's it. For some reason driver >> completely disables the hardware interrupt handling, leaving channel in >> unusable state if transfer is issued with the flag being unset. Note >> that there are no occurrences in the relevant drivers that do not set >> the flag, hence this patch doesn't fix any actual bug and merely fixes >> potential problem. >> >> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx> > > From having a look at this, I am guessing that we have never really > tested the case where DMA_PREP_INTERRUPT flag is not set because as you > mentioned it does not look like this will work at all! > > Is there are use-case you are looking at where you don't set the > DMA_PREP_INTERRUPT flag? No. I just noticed it while was checking whether we really need to handle the BUSY bit state for the Ben's "accurate reporting" patch. > If not I am wondering if we should even bother supporting this and warn > if it is not set. AFAICT it does not appear to be mandatory, but maybe > Vinod can comment more on this. The warning message will be also okay if it's not mandatory.
