Hi, Doug. On 04/07/2015 04:32 AM, Doug Anderson wrote: > Jaehoon, > > On Mon, Apr 6, 2015 at 3:46 AM, Jaehoon Chung <jh80.chung@xxxxxxxxxxx> wrote: >> Hi, Doug. >> >> On 04/04/2015 03:13 AM, Doug Anderson wrote: >>> The Designware databook claims that cmd11 should be finished in 2ms, >>> but my testing showed that not to be the case in some situations. >>> I've seen cmd11 timeouts of up to 130ms (!) during reboot tests. >>> Let's bump the timeout way up so that we're absolutely sure. CMD11 is >>> only sent during card insertion, so this extra timeout shouldn't be >>> terrible. >> >> Is it h/w problem? Could you explain to me about "some situations"? >> As you said, this timeout only used during card inserting. So, it's not critical.. >> But there is much different between 2ms and 500ms(or 130ms). > > Very good question, and it makes sense to dig into this... > > OK, I think I've got it. Dang printk bites me again. I have serial > console enabled and my printouts were actually causing these delays. > With serial console turned off I reliably get ~280us for the interrupt > to fire (tested across SD and WiFi across 137 + 128 + 111 + 127 = 503 > reboots) Oh..agreed. I also think printouts can be caused the delay. Thanks for your explanation. > > I think it makes sense to land this patch anyway, but with an updated > description. I'm happy to repost this or happy if you just want to > update the description when applying. To save your time, when applying, i will do the updating description. Best Regards, Jaehoon Chung > > --- > > Although the cmd11 interrupt should come within 2ms, that's a very > short time. Let's increase the timeout to be really sure that we > don't get an accidnetal timeout. One case in particular this is > useful is if you've got a serial console and printk in just the right > places. Under that scenario I've seen delays of up to 130ms before > the interrupt fired. > > CMD11 is only sent during card insertion, so this extra timeout > shouldn't be terrible. > > --- > > -Doug > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
