Hi Greg, On Tue, Jan 07, 2014 at 08:16:20PM -0800, Greg KH wrote: > > A: No. > Q: Should I include quotations after my reply? > > http://daringfireball.net/2007/07/on_top > > On Wed, Jan 08, 2014 at 03:49:07AM +0000, Tang, Jianqiang wrote: > > Hi, > > 1) I met this issue one time just boot up our Linux Platform(Kernel3.10) with XHCI driver, then kernel panic happen. > > > > And this issue reported once by other internal team. > > > > Nothing special of reproduce step and do not need special Hardware I think. > > > > Just random issue which will happen when meet the timing condition. > > > > 2) This issue is introduced by this patch: > > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=596d789a211d134dc5f94d1e5957248c204ef850 > > > > which set all hub autosuspend delay to 0. > > That patch was released in a kernel almost a full year ago, yet we have > never had a report of this happening before, so are you sure this patch > is the root cause? This bug happened in a platform with 1 usb3 host controller + 1 usb3 OTG controller (Jianqiang, please correct me if I'm wrong). How common is this configuration out there? Br, David Cohen > > > This causes race condition during XHCI driver initialization, > > > > After USB2 hcd and USB2 root hub finish the initialization, USB2 root hub is functional and auto suspend right now, hence trigger XHCI runtime suspend flow; > > > > At the same time, XHCI driver continue to initialize the USB3 hcd and assign to xhci->shared_hcd after finish the initialization; > > > > Since xhci_suspend() use the xhci->shared_hcd, so there is race condition that when XHCI runtime suspend called, xhci->shared_hcd still NULL. > > > > I think this patch is a fix solution since before XHCI finish the whole initialization, USB2 root hub triggered runtime suspend is mean less and do not need to handle. > > With this patch applied, does the crash go away? -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
