Hi Mathias, On Tue, Feb 15, 2022 at 12:16:12PM +0200, Mathias Nyman wrote: > On 14.2.2022 15.53, Pavan Kondeti wrote: > > Hi Mathias, > > > > On Mon, Feb 14, 2022 at 02:51:54PM +0200, Mathias Nyman wrote: > >> On 14.2.2022 14.20, Pavankumar Kondeti wrote: > >>> From: Daehwan Jung <dh10.jung@xxxxxxxxxxx> > >>> > >>> xhci_reset() is called with interrupts disabled. Waiting 10 seconds for > >>> controller reset and controller ready operations can be fatal to the > >>> system when controller is timed out. Reduce the timeout to 1 second > >>> and print a error message when the time out happens. > >>> > >>> Fixes: 22ceac191211 ("xhci: Increase reset timeout for Renesas 720201 host.") > >> > >> > >> The commit 22ceac191211 ("xhci: Increase reset timeout for Renesas 720201 host.") > >> intentionally increased the timeout to 10 seconds as that host might take 9 > >> seconds to complete reset. This was done almost 10 years ago so I don't know > >> if it really is an issue anymore. > >> > >> Anyways, your patch might break Renesas 72021 instead of fixing it. > > > > Unfortunately, yes :-( . We have this reduced timeout patch in our previous > > commercialized products so thought this would be a good time to fix this > > once for all. Since this patch has been 10 years long, not sure if any other > > controllers also need 10 sec timeout. It would probably better > > > >> > >> I agree that busylooping up to 10 seconds with interrupts disabled doesn't make sense. > >> > >> Lets see if there is another solution for your case. > >> > >> - Does a "guard interval" after writing the reset help? > >> For example Intel xHCI needs 1ms before touching xHC after writing the reset bit > > > > I will ask this question to our hardware team. Setting that one quirk from > > DWC3 host might require other changes like this [1]. > >> > >> - Is it the CNR bit or the RESET bit that fails? could be just stuck CNR bit? > > > > The RESET bit never gets cleared from USBCMD register. > > > >> > >> - we only disable local interrupts when xhci_reset() is called from xhci_stop(), > >> and sometimes from xhci_shutdown() and xhci_resume() if some conditions are met. > >> Have you identified which one is the problematic case? > > > > The crash reports I have seen are pointing to > > > > usb_remove_hcd()->xhci_stop()->xhci_reset() > > Ok, so xhci_stop() and xhci_shutdown() both may call xhci_reset() with interrupts > disabled and spinlock held. In both these cases we're not that interested in the > outcome of xhci_reset(). > > But during probe we call xhci_reset() with interrupts enabled without spinlock, > and here we really care about it succeeding. > I'm also guessing reset could take a longer time during probe due to possible recent > BIOS handover, or firmware loading etc. > > So how about passing a timeout value to xhci_reset()? > Give it 10 seconds during probe, and 250ms in the other cases. > Thanks for this suggestion. This sounds better compared to the quirks approach. xhci_resume() also seems to be calling xhci_reset() in the hibernation path, I believe we should treat this like probe()/startup case and give larger timeout. Thanks, Pavan