On Wed, 2016-05-04 at 14:56 +0300, Felipe Balbi wrote: > Hi, > > chunfeng yun <chunfeng.yun@xxxxxxxxxxxx> writes: > >> chunfeng yun <chunfeng.yun@xxxxxxxxxxxx> writes: > >> > On Tue, 2016-05-03 at 12:33 +0300, Felipe Balbi wrote: > >> >> Hi, > >> >> > >> >> chunfeng yun <chunfeng.yun@xxxxxxxxxxxx> writes: > >> >> >> chunfeng yun <chunfeng.yun@xxxxxxxxxxxx> writes: > >> >> >> > On Thu, 2016-04-21 at 10:04 +0800, Chunfeng Yun wrote: > >> >> >> >> Click mouse after xhci suspend completion but before system suspend > >> >> >> >> completion, system will not be waken up by mouse if the duration of > >> >> >> >> them is larger than 20ms which is the device UFP's resume signaling > >> >> >> > >> >> >> what is "them" here ? The duration of what is longer than 20ms ? > >> >> > They are "xhci suspend completion" and "system suspend completion"; > >> >> > > >> >> > It's time duration > >> >> > >> >> okay. So if xhci suspend takes longer than 20ms your SPM doesn't see a > >> >> wakeup ? > >> > It is not the time of xhci suspend consumed, but is the time of duration > >> > from xhci suspend completion to system suspend completion(after BOOT-CPU > >> > is turned off, SPM will be enabled to receive wakeup event) > >> > >> Okay, so SPM will be the entity actually handling wakeups, right ? I'm > >> assuming something like this happens: > >> > >> echo mem > /sys/power/state > >> /* start suspending devices */ > >> xhci_suspend() > >> /* all devices suspended */ > >> enable_spm() > >> > >> so, if a mouse button is pressed after xhci_suspend() returns but before > >> enable_spm() runs, then we're gonna miss that event, am I right ? > > Yes, you are right. > >> > >> I can't think of any way to sort this out. Let's ask on linux-pm (I've > >> added linux-pm to Cc list) > > Thanks > >> > >> >> >> >> lasted. Another reason is that the SPM is not enabled before system > >> >> >> > >> >> >> what's SPM ? > >> >> > It is System Power Management which is powered off when system is > >> >> > running in normal mode, and is powered on when system enters suspend > >> >> > mode. It is used to wakeup system when some wakeup sources, such as > >> >> > bluetooth or powerkey etc, tigger wakeup event. > >> >> > >> >> okay, thanks > >> >> > >> >> >> >> suspend compeltion, this causes SPM also not notice the resume signal. > >> >> >> ^^^^^^^^^^ > >> >> >> completion > >> >> >> > >> >> >> >> So in order to reduce the duration less than 20ms, make use of > >> >> >> >> syscore's suspend/resume interface. > >> >> >> > >> >> >> no, this is the wrong approach > >> >> > But it seems only one workable approach from software side > >> >> > >> >> I wouldn't say that. It seems to me SPM should be enabled earlier. > >> > Yes, but normally SPM should be enabled after all CPUS are turned off, > >> > so it's difficult to do that, I mean enable SPM before turning off CPUS > >> > >> is it a requirement that SPM should be enabled only after all CPUs are > >> turned off ? If that's the case, then any device in the system might > >> have missed wakeups. This doesn't seem like a good design to me; unless > >> I'm missing something... > > Yes, it's a requirement. > > > > If the wakeup source is level trigger, and will keep it until SPM notice > > it. Although USB wakeup is level trigger, but it just last at most 20ms > > and clear itself automatically. > > who's clearing USB wakeup after 20ms ? Sure, it's a requirement by the > USB spec that host should drive reset for *at least* 20ms, but I don't > remember the exact wordings WRT remote wakeup > > /me reads > > Okay, here it is, section 7.1.7.7 of USB 2.0 Spec states: > > "The remote wakeup device must hold the resume signaling for at > least 1 ms but for no more than 15 ms (TDRSMUP). At the end of > this period, the device stops driving the bus (puts its drivers > into the high-impedance state and does not drive the bus to the > J state)." > > IOW, the mouse is not at fault here. Remote wakeup can last anywhere > between 1ms and 15ms. If your system can't cope with it, then I'd say > it's a problem with your system and you shouldn't allow XHCI to go to > such deep power states until SPM is enabled. Yes > > I really tried finding the correct piece of code which does this for PCI > devices, but basically it's treated as an IRQ and as long as > enable_irq_wake() or the sysfs file is set to true, then PME gets > enabled (hopefully PCI folks can confirm this statement). > > Very recently Tony Lindgren added proper handling of wakeup signals as > IRQs for non-PCI systems too (see 4990d4fe327b PM / Wakeirq: Add > automated device wake IRQ handling), wonder if you could treat SPM > similarly. We can't make use of device's interrupt as wake IRQ, because there is no IRQ when xHCI enters suspend mode. Thanks > -- 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
