On 07/31/2013 04:35 AM, Sekhar Nori wrote: > On Wednesday 31 July 2013 10:35 AM, Joel Fernandes wrote: >> On 07/30/2013 03:29 AM, Sekhar Nori wrote: >>> On Monday 29 July 2013 06:59 PM, Joel Fernandes wrote: >>>> We certainly don't want error conditions to be cleared anywhere >>> >>> 'anywhere' is a really loaded term. >>> >>>> as this will make us 'forget' about missed events. We depend on >>>> knowing which events were missed in order to be able to reissue them. >>> >>>> This fixes a race condition where the EMR was being cleared >>>> by the transfer completion interrupt handler. >>>> >>>> Basically, what was happening was: >>>> >>>> Missed event >>>> | >>>> | >>>> V >>>> SG1-SG2-SG3-Null >>>> \ >>>> \__TC Interrupt (Almost same time as ARM is executing >>>> TC interrupt handler, an event got missed and also forgotten >>>> by clearing the EMR). >>> >>> Sorry, but I dont see how edma_stop() is coming into picture in the race >>> you describe? >> >> In edma_callback function, for the case of DMA_COMPLETE (Transfer >> completion interrupt), edma_stop() is called when all sets have been >> processed. This had the effect of clearing the EMR. > > Ah, thanks. I was missing the fact that the race comes into picture only > when using the DMA engine driver. I guess that should be mentioned > somewhere since it is not immediately obvious. > > The patch looks good to me. So if you respin just this one with some > updated explanation based on what you wrote below, I will take it. Sure I'll do that. Also the trigger_channel patch, will you be taking that one too? I can send these 2 in a series as they touch arch/arm/common/edma.c Thanks, -Joel > > Thanks, > Sekhar > > -- > To unsubscribe from this list: send the line "unsubscribe linux-omap" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
