03.02.2020 14:37, Jon Hunter пишет: > > On 01/02/2020 15:13, Dmitry Osipenko wrote: >> 31.01.2020 17:22, Dmitry Osipenko пишет: >>> 31.01.2020 12:02, Jon Hunter пишет: >>>> >>>> On 30/01/2020 20:04, Dmitry Osipenko wrote: >>>> >>>> ... >>>> >>>>>>> The tegra_dma_stop() should put RPM anyways, which is missed in yours >>>>>>> sample. Please see handle_continuous_head_request(). >>>>>> >>>>>> Yes and that is deliberate. The cyclic transfers the transfers *should* >>>>>> not stop until terminate_all is called. The tegra_dma_stop in >>>>>> handle_continuous_head_request() is an error condition and so I am not >>>>>> sure it is actually necessary to call pm_runtime_put() here. >>>>> >>>>> But then tegra_dma_stop() shouldn't unset the "busy" mark. >>>> >>>> True. >>>> >>>>>>> I'm also finding the explicit get/put a bit easier to follow in the >>>>>>> code, don't you think so? >>>>>> >>>>>> I can see that, but I was thinking that in the case of cyclic transfers, >>>>>> it should only really be necessary to call the get/put at the beginning >>>>>> and end. So in my mind there should only be two exit points which are >>>>>> the ISR handler for SG and terminate_all for SG and cyclic. >>>>> >>>>> Alright, I'll update this patch. >>>> >>>> Hmmm ... I am wondering if we should not mess with that and leave how >>>> you have it. >>> >>> I took another look and seems my current v6 should be more correct because: >>> >>> 1. If "busy" is unset in tegra_dma_stop(), then the RPM should be put >>> there since tegra_dma_terminate_all() won't put RPM in this case: >>> >>> if (!tdc->busy) >>> goto skip_dma_stop; >>> >>> 2. We can't move the "busy" unsetting into the terminate because then >>> tegra_dma_stop() will be invoked twice. Although, one option could be to >>> remove the tegra_dma_stop() from the error paths of >>> handle_continuous_head_request(), but I'm not sure that this is correct >>> to do. >> >> Jon, I realized that my v6 variant is wrong too because >> tegra_dma_terminate_all() -> tdc->isr_handler() will put RPM, and thus, >> the RPM enable-count will be wrecked in this case. > > Did you see my other suggestion to move the pm_runtime_put() outside of > tegra_dma_stop? Yes, but seems I skimmed too quickly through the lines and failed to recognize the point you made. > There are only a few call sites for tegra_dma_stop and > so if we call pm_runtime_put() after calling tegra_dma_stop this should > simplify matters. This is somewhat similar to what I made in the v7. Instead of adding pm_runtime_put() after each tegra_dma_stop(), I removed the tegra_dma_stop(). Looking at it once again, perhaps indeed it will be better to leave the relevant tegra_dma_stop() in place (the irrelevant could be removed). Please take a look at the v7, I'll drop the "[PATCH v7 13/19] dmaengine: tegra-apb: Don't stop cyclic DMA in a case of error condition" and make v8 after yours review of the v7. Thanks in advance!
