On Tue, 19 May 2015, Marcel Holtmann wrote: > Hi Alan, > > >>>> I am not convinced. Now we are hacking the Bluetooth core layer > >>>> (which has nothing to do with the drivers suspend/resume or > >>>> probe) to do something different so that we do not see this > >>>> warning. > >>>> > >>>> I can not do anything about the platform in question choosing a > >>>> unplug/replug for suspend/resume instead of having a proper USB > >>>> suspend and resume handling. That is pretty much out of our > >>>> control. > > > > Actually one can do something about this. I mean, one _can_ implement > > proper USB suspend and resume handling in the Bluetooth driver. At > > this point the details aren't clear to me, but perhaps if the driver in > > question had a reset_resume callback then it might work better. > > the btusb.ko driver has suspend/resume support. Are you saying we > also need reset_resume support? I don't know; I'm not familiar enough with how Bluetooth works. If the device loses power and requires its firmware to be loaded again, then a reset_resume would end up doing much the same thing as probe anyway. So implementing reset_resume might not make much difference. > >>>> I would rather have the USB subsystem delay the probe() > >>>> callback if we tell it to. > > > > This is possible. I am not sure it would be the right thing to do, > > though. What happens if the probe routine gets called early on during > > the boot-up procedure, before userspace is up and running? The same > > thing should happen here. > > For modules this will be hard. Since you need userspace before being > able to load the modules. If built-in code, then in theory this might > be possible. Depending on the order of the init sections. Yes, I meant built-in. > >>>> Of just have request_firmware() > >>>> actually sleep until userspace is ready. Seriously, why is > >>>> request_firmware not just sleeping for us. > > > > It won't work. The request_firmware call is part of the probe > > sequence, which in turn is part of the resume sequence. Userspace > > doesn't start running again until the resume sequence is finished. If > > request_firmware waited for userspace, it would hang. > > Then I really have no idea on how to solve this unless we silence the > warning from request_firmware. From a driver perspective we go back > trough probe(). So the driver has to treat this as a new device. Oliver's suggestion to keep the firmware in memory may be the only reasonable solution. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
