Re: xhci power to external device
I "solved" the problem by returning the disk in question ("performance
not as expected") and buying a "desktop" model (which has its own
external power supply). Since it is a 3,5" disk inside instead of a
2,5", it is a bit faster too.
-Olaf.
--
___ Olaf 'Rhialto' Seibert -- "What good is a Ring of Power
\X/ rhialto/at/falu.nl -- if you're unable...to Speak." - Agent Elrond
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Re: xhci power to external device
On Tue, Feb 19, 2019 at 11:30:22AM -0500, Greg Troxel wrote: > > That information is mostly used to calculate the power budget, If > > it would be exceeded, the device isn't allowed to draw more power. > How common is it for USB controllers to actually do this calculation and > selectively enable, vs being built to supply 500/900 per port? > Looking at NetBSD drivers quickly, I don't see this. usb_subr.c:707ff > Certainly current limiting on power supplies is normal. Probably. Hubs notice when the current limit is exceeded, I don't see that our controllers could set a current limit but there is probably some fuse or other current limiter to prevent damage. Greetings, -- Michael van Elst Internet: mlel...@serpens.de "A potential Snark may lurk in every tree."
Re: xhci power to external device
mlel...@serpens.de (Michael van Elst) writes: > USB2 ports are limited to 100mA and devices may communicate that they > want more (up to 500mA) and then are signaled to draw more power. > > USB3 is similar but allows other limits, 150mA default and 900mA max. > There are also USB3 options that allow even more power, e.g. for > USB chargers. Thanks for straigtening me out! > > That information is mostly used to calculate the power budget, If > it would be exceeded, the device isn't allowed to draw more power. How common is it for USB controllers to actually do this calculation and selectively enable, vs being built to supply 500/900 per port? Looking at NetBSD drivers quickly, I don't see this. > Many USB controllers cannot limit the power output, so even when > a device is denied the extra power (or didn't even dare to communicate > and is only allowed the minimum) it could just draw higher currents. That seems cheaper to build. >> I have never heard of a port that can throttle what it supplies. > > Throttling would cause the voltage to drop, which of course happens > when a device tries to draw more current than the port can provide. > A USB controller that limits power output on a port does this to > protect the port. Certainly current limiting on power supplies is normal. How common is it for a USB controller to not only have current limiting for the 500/900 level (to protect the port hardware as you say) to also have configured lower current limiting so that devices that should be under 100/150 will be prevented from going much over that? Overall, it sounds to me like Rhialto's problem is more likely some kind of bug, dodgy wiring, marginal power supply, etc.
Re: xhci power to external device
g...@lexort.com (Greg Troxel) writes: >Rhialto writes: >> I have an external harddisk, like so: (output from usbdevs -v) >> >> Controller /dev/usb0: >> addr 0: super speed, self powered, config 1, xHCI Root Hub(0x), vendor >> 8086(0x8086), rev 1.00(0x0100) >> port 1 addr 9: super speed, power 224 mA, config 1, Elements 25A1(0x25a1), >> Western Digital(0x1058), rev 10.14(0x1014), serial >> >> I have some reason to believe it does nog get enough power from the >> port. Is the "power 224 mA" how the current is actually limited? Or can >> the device draw more without telling us? >My impression is: > USB ports and devices are limited to 500 mA, per the spec. (But, > there are various schemes for USB chargers to communciate that they > support more, so devices can be willing to draw more) USB2 ports are limited to 100mA and devices may communicate that they want more (up to 500mA) and then are signaled to draw more power. USB3 is similar but allows other limits, 150mA default and 900mA max. There are also USB3 options that allow even more power, e.g. for USB chargers. That information is mostly used to calculate the power budget, If it would be exceeded, the device isn't allowed to draw more power. Many USB controllers cannot limit the power output, so even when a device is denied the extra power (or didn't even dare to communicate and is only allowed the minimum) it could just draw higher currents. Some USB controllers that can limit the power output only switch between minimum and unlimited. That's also allowed so that a USB2 device asking for 500mA can actually draw 900mA on a USB3 port without violating the spec. > I have never heard of a port that can throttle what it supplies. Throttling would cause the voltage to drop, which of course happens when a device tries to draw more current than the port can provide. A USB controller that limits power output on a port does this to protect the port. -- -- Michael van Elst Internet: mlel...@serpens.de "A potential Snark may lurk in every tree."
Re: xhci power to external device
Rhialto writes: > I have an external harddisk, like so: (output from usbdevs -v) > > Controller /dev/usb0: > addr 0: super speed, self powered, config 1, xHCI Root Hub(0x), vendor > 8086(0x8086), rev 1.00(0x0100) > port 1 addr 9: super speed, power 224 mA, config 1, Elements 25A1(0x25a1), > Western Digital(0x1058), rev 10.14(0x1014), serial > > I have some reason to believe it does nog get enough power from the > port. Is the "power 224 mA" how the current is actually limited? Or can > the device draw more without telling us? My impression is: USB ports and devices are limited to 500 mA, per the spec. (But, there are various schemes for USB chargers to communciate that they support more, so devices can be willing to draw more) what you are seeing is the device's declaration of how much power it will draw there is, very maybe, some notion that a computer will only enable a port if some power conditions are met, such as the total declared power of all enabled devices remains below some level believed to be what can in aggregate is supplied. But I'm not sure this exists. I have never heard of a port that can throttle what it supplies. I have definitely seen problems from trying to pull too much power in various ways. I don't have a good reason to believe all ports in any one computer will have exactly the same behavior. if you have an external disk that is USB powered, and it's flaky, you should get a powered hub
Re: xhci power to external device
On Sun 17 Feb 2019 at 21:34:44 +0100, Rhialto wrote: > I have an external harddisk, like so: (output from usbdevs -v) > > Controller /dev/usb0: > addr 0: super speed, self powered, config 1, xHCI Root Hub(0x), vendor > 8086(0x8086), rev 1.00(0x0100) > port 1 addr 9: super speed, power 224 mA, config 1, Elements 25A1(0x25a1), > Western Digital(0x1058), rev 10.14(0x1014), serial To make things more interesting, I connected it to a laptop which has USB 2, not 3, and under Linux "lsusb -v" says bmAttributes 0x80 (Bus Powered) MaxPower 500mA On the same laptop, with NetBSD 8, also 500 mA: Controller /dev/usb7: addr 1: high speed, self powered, config 1, EHCI root hub(0x), vendor 8086(0x8086), rev 1.00(0x0100) port 1 addr 2: high speed, power 500 mA, config 1, Elements 25A1(0x25a1), Western Digital(0x1058), rev 10.14(0x1014), serial When I try the same on the original computer in a USB 2 port, I get the same result. On a MacBook (which does have USB 3), "System Information" says "Current Available (mA): 900" and "Current Required (mA): 896". And on a laptop with Linux and USB 3 ports, the same "224 mA" number is shown by lsusb -v. So there seems some confusion about the number, which supposedly is reported by the device and simply believed by the computer. So inspired by seeing "500 mA" on USB-2 ports, I plugged the disk into a USB-2 port on the original computer, and I don't see the symptoms (yet??) that made me think that there was a power problem. Can anyone shed some light on this? -Olaf. -- ___ Olaf 'Rhialto' Seibert -- "What good is a Ring of Power \X/ rhialto/at/falu.nl -- if you're unable...to Speak." - Agent Elrond signature.asc Description: PGP signature
xhci power to external device
I have an external harddisk, like so: (output from usbdevs -v) Controller /dev/usb0: addr 0: super speed, self powered, config 1, xHCI Root Hub(0x), vendor 8086(0x8086), rev 1.00(0x0100) port 1 addr 9: super speed, power 224 mA, config 1, Elements 25A1(0x25a1), Western Digital(0x1058), rev 10.14(0x1014), serial I have some reason to believe it does nog get enough power from the port. Is the "power 224 mA" how the current is actually limited? Or can the device draw more without telling us? For comparison, there is another device like so, which is a SD card reader: Controller /dev/usb3: addr 1: high speed, self powered, config 1, EHCI root hub(0x), vendor 8086(0x8086), rev 1.00(0x0100) port 1 addr 2: high speed, self powered, config 1, Rate Matching Hub(0x0024), Intel(0x8087), rev 0.00(0x) ... port 6 addr 3: high speed, power 500 mA, config 1, USB Storage(0x0723), Generic(0x05e3), rev 94.51(0x9451) so at least some devices can draw that much. If the given 224 mA are actually enforced, can I give the disk more anyway? -Olaf. -- ___ Olaf 'Rhialto' Seibert -- "What good is a Ring of Power \X/ rhialto/at/falu.nl -- if you're unable...to Speak." - Agent Elrond signature.asc Description: PGP signature
