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.
Signed-off-by: Yinbo Zhu <zhuyinbo@xxxxxxxxxxx>
---
Change in v3:
Rework the commit information.
Move the patch code change to lower down position in ohci_irq.
drivers/usb/host/ohci-hcd.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
index 1f5e693..87aa9bb 100644
--- a/drivers/usb/host/ohci-hcd.c
+++ b/drivers/usb/host/ohci-hcd.c
@@ -879,7 +879,8 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd)
{
struct ohci_hcd *ohci = hcd_to_ohci (hcd);
struct ohci_regs __iomem *regs = ohci->regs;
- int ints;
+ int ints, ctl;
+
Extra blank line not needed.
/* Read interrupt status (and flush pending writes). We ignore the
* optimization of checking the LSB of hcca->done_head; it doesn't
@@ -969,9 +970,15 @@ static irqreturn_t ohci_irq (struct usb_hcd *hcd)
* when there's still unlinking to be done (next frame).
*/
ohci_work(ohci);
- if ((ints & OHCI_INTR_SF) != 0 && !ohci->ed_rm_list
- && ohci->rh_state == OHCI_RH_RUNNING)
+
+ ctl = ohci_readl(ohci, ®s->control);
+
Blank lines not needed.
+ if (((ints & OHCI_INTR_SF) != 0 && !ohci->ed_rm_list
+ && ohci->rh_state == OHCI_RH_RUNNING) ||
+ ((ctl & OHCI_CTRL_HCFS) != OHCI_USB_OPER)) {
ohci_writel (ohci, OHCI_INTR_SF, ®s->intrdisable);
+ (void)ohci_readl(ohci, ®s->intrdisable);
+ }
This is definitely wrong. You must not turn off SF interrupts when
ed_rm_list is non-NULL. If you do, the driver will not be able to
finish unlinking URBs.
Alan Stern
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.
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);
...
}
BRS,
Yinbo Zhu.
