On Tue, Jul 3, 2018 at 10:14 PM, Marek Vasut <ma...@denx.de> wrote: > On 07/03/2018 05:22 PM, Andre Przywara wrote: >> Hi, >> >> On 02/07/18 22:57, Marek Vasut wrote: >>> On 07/02/2018 11:40 PM, Tom Rini wrote: >>>> On Mon, Jul 02, 2018 at 11:27:58PM +0200, Marek Vasut wrote: >>>>> On 07/02/2018 10:53 PM, Jagan Teki wrote: >>>>>> During usb shutdown or 'usb reset' all the necessary clocks >>>>>> on the specific controller will disable. Usually this shutdown >>>>>> happen during U-Boot proper handoff to Linux. >>>>> >>>>> No, 'usb reset' can be triggered by the user any time. >>>> >>>> Yes, and it's also triggered as part of the hand-off, which is the use >>>> case in question. >>> >>> No, that's not true. The USB controllers are torn down when starting the >>> OS, which is a different thing from usb reset, which brings them back up >>> and rescans the bus too. >>> >>>>>> There is an issue in Allwinner A64, is during OHCI1 shutdown >>>>>> the controller is unable to access the register space >>>>>> so the Linux boot hangs at this place. >>>>> >>>>> This doesn't make any sense, Linux should enable the necessary clock >>>>> before accessing any controller registers, unless there is a bug in Linux. >>>> >>>> Should but doesn't always? So yes, there's possibly / hopefully a bug >>>> in the dts files. >>> >>> How did you reach that conclusion about the DTS files ? There is a bug >>> in Linux, but it's likely in the driver which doesn't enable the clock >>> before accessing the registers. >>> >>> But maybe the description here is completely confusing, since the output >>> down below would indicate this hang is still in U-Boot. >> >> Yes, it is. There is no bug in Linux. >> >> U-Boot trips over its own feet when bringing down the USB controllers: >> It shutdowns one part (EHCI or OHCI) on the register level, then turns >> off the clocks and reset gates. But because they are shared between >> controllers, this turns off the other controller as well. Then it tries >> to bring down the the second part (OHCI or EHCI, respectively) on the >> USB register level, which hangs, because the AHB clock is already off. >> As this just happens quite late, it looks like U-Boot already said >> goodbye, but it actually hasn't completely finished. >> So Linux is completely fine and the bug is entirely in U-Boot. >> My patch [1] tries to paper^Wsolve this in a different way, though it >> isn't perfect either. I think there is a bit more to it than I assumed >> yesterday, so I need to go back to the code later tonight to see what's >> really going on (I suspect it's about OHCI 0 and 1 sharing a clock, not >> about EHCI and OHCI). > > Well, please keep poking. > > Maybe a dumb idea, but what about enabling the clock at the beginning of > remove function to guarantee they are ON and then disabling the clock at > the end of the function. Would that work maybe ? ie. > > .remove() { > clk_enable(..); > readl()/writel()/... > clk_disable(..); > }
I've verified clock bits before disabling, and bits are enabled as usual. and even verified your idea of enabling before disable[2] => usb reset resetting USB... ohci_usb_remove: input mask = 0x10000, input usb_clk_cfg = 0x30303 ohci_usb_remove: usb_clk_cfg = 0x20303 EHCI failed to shut down host controller. [2] https://paste.ubuntu.com/p/V9KKxMx6Cj/ _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot