I've just tested AR9271 with additional Y USB cable which occupy two USB ports. No difference.
athn0: could not load firmware message appears when connect it to USB2 ports, but firmware loads successfully when AR9271 connected to USB3 on AMD GX-420CA SOC. On 7/28/2018 10:04 PM, Denis wrote: > As for USB3.0 spec USB Host can provide up to 900mA to a device > connected 0.9A*5V=4.5W total. USB2.0 has no more than 500mA so <=2.5W > USB device can be connected. > > I'm sure AR9271 has <2.5W during firmware loading procedure but it must > be checked in case of fit-pc has out of spec power per USB2.0 port. > > Going to perform some checks soon. > > > On 7/27/2018 2:22 PM, Kevin Chadwick wrote: >> On Fri, 27 Jul 2018 12:22:08 +0300 >> >> >>> There is no any external hub or cable between AR9271 usb stick. I >>> attach it directly to AMD GX-420CA SOC with Radeon(tm) HD Graphics >>> PC. Firmware does not load when it attached to any of USB2.0 ports. >>> But when it attached to USB3.0 AR9271 works without any errors. >> >> >> USB3 provides more current than USB2, so this may make sense with the >> current theory of some USB2 boards not supplying enough power for >> these devices. >> >> USB has to protect against user insertion, damaged ports etc. so surges >> are filtered more so than required for USB via pci-ex. >> >> I wonder if the firmware loading speed can be dialed down so that less >> power is required (perhaps it saves memory by verifying as received) or >> more likely the issue occurs after upload completion? Is the open >> firmware a different size or sets different power settings? Are any >> power affecting settings available before firmware upload? >> >> If the power usage is close to the limit then it may cause micro >> reset/failure a varying percentage of the time. >> >> Sorry if all this has already been considered. >> >
