Re: [PATCH v3] usb: ohci: add check for host controller functional states

[zhuyinbo]

在 2021/10/11 下午1:10, zhuyinbo 写道:
> 在 2021/10/10 上午3:39, Alan Stern 写道:
> > On Sat, Oct 09, 2021 at 10:01:25AM +0800, zhuyinbo wrote:
> > > 在 2021/10/8 下午10:26, Alan Stern 写道:
> > > > On Fri, Oct 08, 2021 at 03:26:10PM +0800, Yinbo Zhu wrote:
> > > > > The usb states of ohci controller include UsbOperational, UsbReset,
> > > > > UsbSuspend and UsbResume. Among them, only the UsbOperational state
> > > > > supports launching the start of frame for host controller according
> > > > > the ohci protocol spec, but in S3/S4 press test procedure, it may
> > > > Nobody reading this will know what "S3/S4 press test procedure" means.
> > > > You have to explain it, or use a different name that people will
> > > > understand.
> > > okay, I got it.
> > > > > happen that the start of frame was launched in other usb states and
> > > > > cause ohci works abnormally then kernel will allways report rcu
> > > > > call trace. This patch was to add check for host controller
> > > > > functional states and if it is not UsbOperational state that need
> > > > > set INTR_SF in intrdisable register to ensure SOF Token generation
> > > > > was been disabled.
> > > > This doesn't make sense.  You already mentioned that only the
> > > > UsbOperational state supports sending start-of-frame packets.  So 
> > > > if the
> > > > controller is in a different state then it won't send these packets,
> > > > whether INTR_SF is enabled or not.
> > > >
> > > > What problem are you really trying to solve?
> > > Only UsbOperational state supports sending start-of-frame packets, 
> > > but in
> > > fact, in S3/S4 press test procedure,
> > >
> > > usb in non-UsbOperational state that send start-of-frame packets but hc
> > > driver doesn't deal with this frame. and hc will
> > >
> > > allways lauched the SOF for finishing the frame, the cpu will hand 
> > > this sof
> > > interrupt and doesn't deal with time interrupt
> > >
> > > that will cause rcu call trace then system doesn't suspend to 
> > > memory/disk.
> > I still don't understand.
> >
> > Are you saying that your OHCI controller behaves badly because it sends
> > SOF packets even when the state is different from UsbOperational?
>
> HC will allways report the SoF interrupt in the all time when HC was 
> not in NO-UsbOperation state.
>
> and no WritebackDoneHead interrupt that is the issue phenomenon. and 
> this situation is badly state for ohci.
>
> > > Hi Alan Stern,
> > >
> > >      even though ed_rm_list is non-NULL, if hc in non-UsbOperation 
> > > state set
> > > SoF status in usbsts register that is illegal,
> > >
> > > at this time hcd doesn't need care URB whether finished, because hc had
> > > into a wrong state. even thoug it doesn't has this patch,
> > >
> > > URB was not be able to finish when hc in above worng state. except 
> > > software
> > > can intervence this wrong state. but the SoF bit of usbsts
> > >
> > > register was set by HC, and this action will happen always !!! software
> > > clear SoF state I think it isn't make sense. software only disable SoF
> > >
> > > interrupt to fix HC wrong state.
> > This problem happens when you go into S3 or S4 suspend, right? So you
> > should fix the problem by disabling INTR_SF when the root hub is
> > suspended.  Try adding
> >
> >     /* All ED unlinks should be finished, no need for SOF interrupts */
> >     ohci_writel(ohci, OHCI_INTR_SF, &ohci->regs->intrdisable);
> >
> > into ohci_rh_suspend(), just before the update_done_list() call.  If you
> > add this then INTR_SF will not be enabled during S3 or S4 suspend, so
> > the problem shouldn't occur.  Does that work for you?
>
> The system doesn't suspend to disk completely by my test result and hc 
> will always produce SoF interrupt.
>
> I encountered SoF interrupt  issue when HC in UsbSuspend state. and I 
> think when hc in
>
> UsbResume/UsbRest/ SoF interrupt issue may be happen so I disable 
> INTR_SF in ohci_irq.
>
> So I think disable INTR_SF in suspend function which this way isn't 
> good for me.
>
>     In addition, I hope my patch was not only fix the bug i 
> encountered and it can limit HC into badly state and it should be the
>
> base limit condition and prevent more unknown problems.  In fact, HC 
> doesn't deal with ed/td list and done list by the ohci spec, so
>
> I think my patch has no risk for ohci.
>
>       by the way, root hub state isn't completely same with HC, but 
> the root hub reset and resume signaling are controlled by the hcfs bits.
>
> and hcd can set hcfs to decide hc usb state, so I judge whether set 
> SF_INT to interrupt disable register only depend on HC state.

And I have a test, ohci_rh_suspend was called that HC state as gerneral 
was also UsbOperational state whatever do s3/s4 test or power on to boot 
kernel.

but HCD record it as suspend state on root hub at this time.

> > >        In additon, when kernel include my patch, that it does't 
> > > happen about
> > > what you descriped that driver will not be able to finish unlinging 
> > > URBs.
> > >
> > > Because above issue happen in S3/S4(Suspend to disk/Suspend to mem) 
> > > test
> > > procedure, if ed_rm_lis is no-NULL but my patch disable SoF interrupt.
> > >
> > > then when S3/S4 recovery to cpu idle state that usb resume will be 
> > > called,
> > > reume function has following logic, URB will continue to be processed.
> > >
> > >        static int ohci_rh_resume (struct ohci_hcd *ohci)
> > >
> > >       {
> > >
> > >          ...
> > >
> > >          242         if (ohci->ed_rm_list)
> > >          243                 ohci_writel (ohci, OHCI_INTR_SF,
> > > &ohci->regs->intrenable);
> > >
> > >         ...
> > >
> > >        }
> > I'm worried that your patch may disable INTR_SF even when the controller
> > has not gone into S3 or S4 suspend.  Maybe this won't cause problems,
> > but it's better to be safe and do the disable _only_ when a suspend
> > occurs.
> >
> > Alan Stern
>
> Hi  Alan Stern,
>
>     According to the previous statement, I think my patch has no risk 
> on ohci.