On Sat, Oct 09, 2021 at 10:01:25AM +0800, zhuyinbo wrote:

在 2021/10/8 下午10:26, Alan Stern 写道:

quoted

On Fri, Oct 08, 2021 at 03:26:10PM +0800, Yinbo Zhu wrote:

quoted

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.

quoted

quoted

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?

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?

      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