Am Dienstag, 27. Februar 2018, 21:47:11 CET schrieb Douglas Anderson: > Back in the early days when gru devices were still under development > we found an issue where the WiFi reset line needed to be configured as > early as possible during the boot process to avoid the WiFi module > being in a bad state. > > We found that the way to get the kernel to do this in the earliest > possible place was to configure this line in the pinctrl hogs, so > that's what we did. For some history here you can see > <http://crosreview.com/368770>. After the time that change landed in > the kernel, we landed a firmware change to configure this line even > earlier. See <http://crosreview.com/399919>. However, even after the > firmware change landed we kept the kernel change to deal with the fact > that some people working on devices might take a little while to > update their firmware. > > At this there are definitely zero devices out in the wild that have > firmware without the fix in it. Specifically looking in the firmware > branch several critically important fixes for memory stability landed > after the patch in coreboot and I know we didn't ship without those. > Thus, by now, everyone should have the new firmware and it's safe to > not have the kernel set this up in a pinctrl hog. > > Historically, even though it wasn't needed to have this in a pinctrl > hog, we still kept it since it didn't hurt. Pinctrl would apply the > default hog at bootup and then would never touch things again. That > all changed with commit 981ed1bfbc6c ("pinctrl: Really force states > during suspend/resume"). After that commit then we'll re-apply the > default hog at resume time and that can screw up the reset state of > WiFi. ...and on rk3399 if you touch a device on PCIe in the wrong way > then the whole system can go haywire. That's what was happening. > Specifically you'd resume a rk3399-gru-* device and it would mostly > resume, then would crash with some crazy weird crash. > > One could say, perhaps, that the recent pinctrl change was at fault > (and should be fixed) since it changed behavior. ...but that's not > really true. The device tree for rk3399-gru is really to blame. > Specifically since the pinctrl is defined in the hog and not in the > "wlan-pd-n" node then the actual user of this pin doesn't have a > pinctrl entry for it. That's bad. > > Let's fix our problems by just moving the control of > "wlan_module_reset_l pinctrl" out of the hog and put them in the > proper place. > > NOTE: in theory, I think it should actually be possible to have a pin > controlled _both_ by the hog and by an actual device. Once the device > claims the pin I think the hog is supposed to let go. I'm not 100% > sure that this works and in any case this solution would be more > complex than is necessary. > > Reported-by: Marc Zyngier <marc.zyngier@xxxxxxx> > Fixes: 48f4d9796d99 ("arm64: dts: rockchip: add Gru/Kevin DTS") > Fixes: 981ed1bfbc6c ("pinctrl: Really force states during suspend/resume") > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> applied as fix for 4.16 with the 2 Tested-tags Thanks Heiko -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
