Craig McQueen wrote: > Xose Vazquez Perez wrote: > > Craig McQueen wrote: > > > > > I have a D-Link DWA-140 USB Wi-Fi device which is rt2800 based (5392 > > > chipset). I'm trying to use it on a BeagleBone Black based system > > > with 3.14.x kernel built with Yocto. We're using ConnMan 1.30 at the > moment. > > > > Try it with a _desktop x86_64 distribution_ , with a *recent kernel* > > as > > Fedora: (WORK is gnome) > > https://alt.fedoraproject.org/pub/alt/live-respins/ > > Hmm, that is non-trivial but I may try it. > > For now, I'll also try a 4.4.6 kernel running on a BeagleBone Black (with a > USB > hub to work around another issue with the rt2800usb driver crashing as > described in another e-mail). > > > > We've been finding some instabilities with it periodically > > > disconnecting from some networks. So we tried upgrading the firmware > > > file rt2870.bin from version 0.29 to 0.36. That seems to be more > > > stable with the network. However, we're finding that it initially > > > doesn't connect, until the Wi-Fi has been disabled and then re-enabled. ' > > scan wifi' > > > and 'iwlist scan' don't return anything until Wi-Fi has been > > > disabled and then re-enabled. > > > > Don't use any wrapper(NM, ConnMan, wicd, ...), usually are buggy. You > > should use raw commands "iw" and "wpa_supplicant". Hints: > > https://wireless.wiki.kernel.org/en/users/documentation/iw and > > wpa_supplicant always running with "-Dnl80211" > > Okay, I've stripped down the system so ConnMan, udev rules aren't running. > > On all systems, after plugging in the device, I have to issue: > > ip link set wlan0 up > > After this, I try to do a scan: > > iw dev wlan0 scan > > On kernel 4.4.6, with firmware 0.36, it works fine (lists APs it finds). On > kernel > 3.14.x, with firmware 0.29, it works fine. But on kernel 3.14.x, with firmware > 0.36, it returns nothing. But then, if I do this: > > ip link set wlan0 down > ip link set wlan0 up > iw dev wlan0 scan > > Then it works fine. > > So, the question is, why does firmware 0.36 with kernel 3.14.x not work until > I've made the interface go up, then down, and then up again?
I've managed to build, using Yocto, kernel 4.4.12 for BeagleBone. When I run it, it has the same problem. That's different from the Ubuntu 16.04 for BeagleBone using 4.4.6 kernel. With my Yocto build, it had a different version of the 'ip' and 'iw' commands. So I tried copying the Ubuntu versions, but that didn't make a difference. I tried using the Yocto built 4.4.12 kernel with the Ubuntu root filesystem, but it halted during the boot process (don't know why). My best guess is that there's some kernel config difference that makes a difference, but there are many differences, so I'm not sure which one it might be. I'm not sure at this point how to narrow it down to the root cause. Any advice? I wonder if maybe there's a race condition in the rt2800usb driver between loading the rt2870.bin firmware and doing the interface-up initialisation. Normally the firmware loads at the point of doing the 'iw link set wlan0 up' command. Is there a way to force the firmware to load before that command? -- Craig McQueen
