Hi, On 2/28/2018 1:00 PM, Zengtao (B) wrote: > Hi johnyoun: > > I found a suspected bug, and I am writing to confirm with you. > > In the function dwc2_gadget_complete_isoc_request_ddma(drivers/usb/dwc2/gadget.c). > Only the first request from the eq queue is processed while maybe there are more than one descriptors done by the HW. > > 1. Each usb request is associated with a DMA descriptor, but this is not reflect in the driver, so when one DMA descriptor is done, > we don't know which usb request is done, but I think if only one DMA descriptor is done, we can know that the first USB request in > eq queue is done, because the HW DMA descriptor and SW usb request are both in sequence. > > 2. In the function dwc2_gadget_complete_isoc_request_ddma, we may complete more than one DMA descriptor but only the first > Usb request is processed, but in fact, we should all the usb requests associated with all the done DMA descriptors. > > 3. I noticed that each DMA descriptor is configured to report an interrupt, and if each DMA descriptor generate an interrupt, the above > Flow should be ok, but the interrupts can merge and we have used the depdma to figure out the largest finished DMA descriptor index. > Why you suspect that subsequent interrupts can be merged? Did you see this case? Can you provide a log? Even in case of minimal interval=1, time between 2 subsequent interrupts should be about 125us. It's fully enough to process target descriptor, complete request, enqueue new request and prepare new descriptor. Thanks, Minas > Looking forward your reply. > > Thank you. > > Regards > Zengtao > -- > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at https://urldefense.proofpoint.com/v2/url?u=http-3A__vger.kernel.org_majordomo-2Dinfo.html&d=DwIDAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=6z9Al9FrHR_ZqbbtSAsD16pvOL2S3XHxQnSzq8kusyI&m=vbKt9jwY5FRUysFlZg1CB6HKRyFACygkwZBO0mvSQDc&s=7rLKr3g3UyOZT22GAer-w5wDtv-Bb5awlncAJQ1OICM&e= > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
