Hi James, > > > We set gap to 0xff, which we think is a special value that means the > > > device will wait for the host to acknowledge before sending data to > > > the host. > > > > Yes, gap=0xff should be used. Actually I also have the patch to set > > gap to 0xff queued in my local tree. I will send it upstream. > > Thanks. Today I have been testing with gap 50ms and no longer able to > reproduce the "mmc0: Timeout waiting for hardware interrupt." problem. Hmm, that's interesting. The concern of none-0xff gap was that the SDIO interrupt could come in without acknowledgement from host. As long as XO-4 system (specifically mmc subsystem) can wake up within 50ms you are fine. > > > > Looking through history of development, we thought that this would > > > avoid a race condition, where the host starts to suspend, configures > > > the device for host sleep, but the device may wake in the time before > > > the host suspends. > > > > > > We don't see this "mmc0: Timeout waiting for hardware interrupt." > > > problem unless we use WPA2. It does not reproduce on an open access > > > point. > > > > With WPA2 enabled, does the "mmc0 timeout" happen in every suspend > > attempt? > > No, it is rare, of the order of one in every 6000 attempts, and depends > on the timing of arriving packets. Our reproducer uses a ping ramp, > with interval varying from 0.1 to 0.9 seconds with 50ms increment, and > this brings the problem frequency down to about one in 200 attempts. > > The OLPC XO-4 by default tries to suspend automatically when user is > idle, which is why we notice the problem. Good to know. Thanks, Bing -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
