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Message-ID: <20140415184941.GD21101@oc0268524204.ibm.com> Date: Tue, 15 Apr 2014 15:49:41 -0300 From: Thadeu Lima de Souza Cascardo <cascardo@...ux.vnet.ibm.com> To: Stefani Seibold <stefani@...bold.net> Cc: Benjamin Herrenschmidt <benh@....ibm.com>, linux-usb <linux-usb@...r.kernel.org>, linux-kernel@...r.kernel.org, Greg KH <greg@...ah.com>, Alan Stern <stern@...land.harvard.edu>, sarah.a.sharp@...ux.intel.com Subject: Re: Missing USB XHCI and EHCI reset for kexec On Tue, Apr 15, 2014 at 08:42:58PM +0200, Stefani Seibold wrote: > Am Dienstag, den 15.04.2014, 15:33 -0300 schrieb Thadeu Lima de Souza > Cascardo: > > On Tue, Apr 15, 2014 at 05:00:28PM +0200, stefani@...bold.net wrote: > > > > > > Zitat von Thadeu Lima de Souza Cascardo <cascardo@...ux.vnet.ibm.com>: > > > > > > >On Tue, Apr 15, 2014 at 12:04:17PM +0200, stefani@...bold.net wrote: > > > >> > > > >>Zitat von Thadeu Lima de Souza Cascardo <cascardo@...ux.vnet.ibm.com>: > > > >> > > > >>>On Mon, Apr 14, 2014 at 05:44:58PM +0200, stefani@...bold.net wrote: > > > >>>> > > > >>>>Zitat von Benjamin Herrenschmidt <benh@....ibm.com>: > > > >>>> > > > >>>>>I don't know about EHCI specifically but this is a known issue with > > > >>>>>XHCI, I observe similar issues on other powerpc platforms (servers) > > > >>>>>and this isn't architecture specific (looks more like actualy xhc > > > >>>>>implementation specific). > > > >>>>> > > > >>>>>Thadeu Cascardo (on CC) has been the one investigating that on our side, > > > >>>>>he might have more to add including patches. > > > >>>>> > > > >>>> > > > >>>>I have now a kernel 3.14 dmesg log of the problem. After a kexec the > > > >>>>kexeced 3.14 kernel shows: > > > >>>> > > > >>>>[ 1.170029] xhci_hcd 0001:03:00.0: xHCI Host Controller > > > >>>>[ 1.175306] xhci_hcd 0001:03:00.0: new USB bus registered, > > > >>>>assigned bus number 1 > > > >>>>[ 1.212561] xhci_hcd 0001:03:00.0: Host not halted after 16000 > > > >>>>microseconds. > > > >>>>[ 1.219621] xhci_hcd 0001:03:00.0: can't setup: -110 > > > >>>>[ 1.224597] xhci_hcd 0001:03:00.0: USB bus 1 deregistered > > > >>>>[ 1.230021] xhci_hcd 0001:03:00.0: init 0001:03:00.0 fail, -110 > > > >>>>[ 1.235955] xhci_hcd: probe of 0001:03:00.0 failed with error -110 > > > >>>> > > > >>> > > > >>>What is your controller vendor and device IDs? Is that a TI chip? > > > >>> > > > >> > > > >>Yes it is a TI chip, vendor ID 104c and product ID 8241. > > > >> > > > >>>Can you check if the patch I sent a month ago fixes it? [1] There's the > > > >>>whole story there. In fact, you will also need something like the patch > > > >>>below. Can you apply only the first one, verify, and, then, the other > > > >>>one as well, and report what worked for you? > > > >>> > > > >>>[1] http://marc.info/?l=linux-usb&m=139483181809062&w=2 > > > >>> > > > >> > > > >>I tried the attach patch and it did not help. This is what i > > > >>expected because this is a fix in the shutdown path, which will > > > >>never called when doing a forced kexec. > > > > > > > >Hi, Stefani. > > > > > > > >Did you try with both patches applied? How do you evoke the forced > > > >kexec? Is that a kexec on panic? Does it really need to be forced? With > > > >no clean shutdown, platform and drivers would need to issue resets, like > > > >you mentioned below, to get the system into a clean state. > > > > > > > > > > Yes, i applied both patches. But without success. > > > > > > IMHO i think it is necessary to bring the device i a clean state > > > when the driver use the HW. > > > > > > >> > > > >>I have a running a 3.10.23 kernel. This kernel do a kexec for a > > > >>kernel 3.14. Since the kernel 3.10.23 did not performe a clean > > > >>shutdown, the state of the XHCI Controller is undefined. So when > > > > > > > >And the clean shutdown requires both of my patches, for TI chips, as far > > > >as I know. It looks like the problem is issuing a halt when there are > > > >pending URBs. > > > > > > > >>kernel 3.14 will probe XHCI it will find a XHCI controller which was > > > >>not performed a reset. > > > >> > > > > > > > >The problem is not that a reset hasn't been issued. A PCI function reset > > > >should fix most of the problems with a bad device state, when the reset > > > >works. However, the problem is that it was not cleanly shut down. URBs > > > >should have been canceled and removed from the controller queue, and it > > > >should have halted after that. > > > > > > Again, i think it is the job of the driver to bring the chip in a clean state > > > before using them. A driver should never expect a reset state of a chip. > > > > > > > > > > >>So i think it is necessary to reset the XHCI controller and all > > > >>devices on this bus. This is what i do with a "echo 1 > > > >>>/sys/bus/pci/drivers/xhci_hcd/0001:03:00.0/reset" before the kexec. > > > >> > > > > > > > >One way to look at that is making the PCI code issue resets to all buses > > > >before doing any other access. That will make booting more slow, and > > > >there are a lot of other corner cases where this might not be enough. > > > >It's probably more sane to try to get the 3.10.23 kernel to do a clean > > > >shutdown, if possible. > > > > > > > > > > With this driver design the kexec functionality is usesless on PowerPC. > > > X86 looks a little bit better. > > > > > > - Stefani > > > > > > > > > > What is the vendor and device ID you are using on your X86 system? This > > is not a matter of what architecture you are using, it's the XHCI > > controller which does not behave as well as the one you are using on > > X86, which is likely an Intel one. > > > > It is an Intel 8086:8c31. But this was only a side note. We need a > generic solution not a vendor specific one. Otherwise kexec is useless > on other architectures. > > - Stefani > > It's probably "useless" on X86 with a TI XHCI board. I just don't have such an environment to test. Can you arrange to test that? If that shows me wrong, we certainly need to investigate this even further. Thanks. Cascardo. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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