> In general, I think we should adopt a flexible or "loose" model for > acking interrupts on SFF controllers. Agreed - especially as the IRQ is often essentially the drive output not under any kind of sane control of ours. > (a) whenever we are in bus-idle (qc == NULL), and get an interrupt, go > ahead and read Status. Please call into the driver. Quite a few PATA drivers have multiple IRQ sources, and SATA many. > (b) if we are expecting an interrupt, and receive one, check Status (or > AltStatus if DMAing). Providing we are not mid data transfer (which is why we need to get into enable/disable_irq for some controllers). Right now its a problem that can't occur but on some controllers reading status mid PIO xfer causes joyous things like silent corruption. > (c) if condition "(b)" indicates busy, initiate status polling every > 250ms until timeout occurs or BSY clears. Yep. > (d) if N seconds (4?) elapses without an interrupt, initiate polling. > keep a history of such "fail-over" events, and note each fail-over'd > command's eventual success via polling, success via interrupt, or > timeout. Use that history to decide to switch to 100% polling mode > (i.e. reach conclusion that interrupt delivery is broken, via observation) N = 8 sounds good to me (7 being the normal maximum command timeout) > That should cover no-interrupts, lost interrupts, early interrupts, > screaming interrupts, insane devices, and of course normal operation. Should we also consider resetting the device as one of the strategies (at least once off) Might also want to think at that point about the case of command .... timeout where old IDE checks with the controller to spot lost IRQ cases where a command finished and stuff vanished. Old IDE doesn't do much with it but we could use that as a good hint that we want to switch to polling mode and tell the user their computer sucks. Alan - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
