We should applaud them for standing up and saying "Hey, we cocked up, sorry!"
Linux may have been causing USB disconnects
11–20 of 123 posts
Re: Linux may have been causing USB disconnects
#12Re: Linux may have been causing USB disconnects
#13Now can someone fix the embarrassing network bug in Linux. You know, where if you access a link to a network, or access an open networked path after 255 seconds or so ... You receive a network error. It still begs belief that such a fundamental aspect of Linux is broken ... When I show Linux to newbies and this fault occurs (ie. 100% of the time), I simply say "Linux isn't perfect ..." But inside, I cringe... It occu…
I have TCP connections that have stayed open for months so this is highly unlikely to be a kernel issue. I have no idea what you might be running into as I've never seen anything like that occurring.
Re: Linux may have been causing USB disconnects
#14Wait, if I'm reading this correctly there's no safe resume recovery time which can be guaranteed not to cause devices to drop off the bus. The kernel could wait 10 minutes and devices could still require more than that. That seems like a pretty major issue with the USB specification.
If you issue a database query, you have no particular guarantee that it's going to complete in any finite amount of time. At some point, you simply throw up your hands and say it would be unreasonable to wait any longer, and accept the resulting error condition.
Re: Linux may have been causing USB disconnects
#15Now can someone fix the embarrassing network bug in Linux. You know, where if you access a link to a network, or access an open networked path after 255 seconds or so ... You receive a network error. It still begs belief that such a fundamental aspect of Linux is broken ... When I show Linux to newbies and this fault occurs (ie. 100% of the time), I simply say "Linux isn't perfect ..." But inside, I cringe... It occu…
backing the previous poster here, I've never experienced anything like this at all. "Network error" makes it sound like you're using KDE or GNOME or something, or Samba isn't liking your configuration...
Re: Linux may have been causing USB disconnects
#16Now can someone fix the embarrassing network bug in Linux. You know, where if you access a link to a network, or access an open networked path after 255 seconds or so ... You receive a network error. It still begs belief that such a fundamental aspect of Linux is broken ... When I show Linux to newbies and this fault occurs (ie. 100% of the time), I simply say "Linux isn't perfect ..." But inside, I cringe... It occu…
That's an odd.
Have you eliminated all other variables E.G. Common utility/setting, cabling, switch/router etc..? I've had paths open for much longer than that without access issues.
Re: Linux may have been causing USB disconnects
#17Wait, if I'm reading this correctly there's no safe resume recovery time which can be guaranteed not to cause devices to drop off the bus. The kernel could wait 10 minutes and devices could still require more than that. That seems like a pretty major issue with the USB specification.
The hub knows when the device is ready; just query it. A constant timeout is not needed. A give-up timeout might be employed, but there's no reason that can't be 100's of ms, nobody is waiting on that and it doesn't usually happen anyway.
Re: Linux may have been causing USB disconnects
#18Congrats! But how nobody analysed this bug for 8+ years is a bit of a mystery to me...
Because nobody cares about suspend-resume power mgmt. If it doesn't work, curse it, pull it out and put it back in again, voila it works.
The people who really care about and study the spec, are those who have to support fixed devices i.e. USB devices internal to an appliance. They physically cannot be removed by the user. So suspend/resume has to work.
Embedded programmers have to deal with totally-broken drivers/specs all the time. There are probably 100s of folks who knew about this and dealt with it (bumped the timeout in their embedded kernel to match the devices they support) and never said anything to anybody.
Re: Linux may have been causing USB disconnects
#19Congrats! But how nobody analysed this bug for 8+ years is a bit of a mystery to me...
Well the Linux USB maintainer has spent the last month or so trying to get Linus to be more polite, so I guess those kind of things have a higher priority!
I kid, I kid...
The reason is that it is incredibly difficult to link the disconnect to the cause as the 10ms is likely sufficient in 99% of cases - until it suddenly isn't. This means that you could be running test cases on a certain device for a year, and suddenly the test will fail the day after. When the test case mysteriously fails randomly like that on only a subset of devices, the assumption is that the hardware is faulty. These kind of failures would likely be higher on lower quality, less optimized hardware as well, furthering the perception.
As far as I can tell, the reason this is fixed now is because known good hardware from Intel started exhibiting the same error which got people at Intel to track it down directly, as they knew it wasn't their hardware at fault.
Re: Linux may have been causing USB disconnects
#20Well, that's why you don't hardcode a magic value, nor do you continuously poll the state of a device and rely instead on interrupts: That's what they're made for.
Agreed. There's no reason to slavishly imitate a spec, when you can be more generous or better yet just test and wait.
Embedded programmers know this; you can't ship working appliances without dealing with these issues.