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Putting a lid on USB powerPutting a lid on USB powerPosted Jun 8, 2006 22:12 UTC (Thu) by giraffedata (subscriber, #1954)Parent article: Putting a lid on USB power
The fact is, however, that running hardware outside of its specifications is always a dangerous thing to do. I guess I didn't follow the explanation. What hardware is being run outside its specs? You have a USB device designed to draw 150 mA. It's the only thing on the USB bus and the host port is designed to supply 500 mA. Linux knows all this and allows the device to join the system. What's wrong with that? Others are talking about losing data. How does the old Linux behavior lose data where the new one doesn't?
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Putting a lid on USB power Posted Jun 8, 2006 22:43 UTC (Thu) by ehovland (subscriber, #2284) [Link] > What hardware is being run outside its specs?
I would say that the hub and the USB host controller are the two hardware devices that would be driven to power levels that they were not necessarily specified. Since they were the ones who were suffering the brunt of this issue in older kernels.
Although I doubt running the hub beyond power spec is a serious problem, running the usb host controller hardware out of spec could cause no end of problems that may be difficult to diagnose if it is drawing too much power.
Putting a lid on USB power Posted Jun 9, 2006 2:00 UTC (Fri) by giraffedata (subscriber, #1954) [Link] I thought the article was saying that Linux knows the capacity of the host USB controller hardware and therefore knows that it is within specs if the USB device is allowed to power up. Otherwise, what is the point of the device telling Linux how much current it needs?
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