Hi Tony,
On 12/08/2016 09:37 AM, Tony Lindgren wrote:
> * Felipe Balbi <balbi@xxxxxxxxxx> [161208 01:45]:
>> Tony Lindgren <tony@xxxxxxxxxxx> writes:
>>> Somehow starting with v4.9-rc7 there have been imprecise
>>
>> There's nothing touching dwc3 since v4.9-rc5.
>
> Right, nothing obvious has changed. I think it's just a slight timing
> change in the code that started triggering it.
>
>>> external aborts on omap5-uevm dwc3 controller. I have not been
>>> able to bisect what exactly triggered this as it does not always
>>> happen. It seems that something changed with probing that
>>> now exposes the issue:
>>>
>>> Unhandled fault: imprecise external abort (0x1406) at 0x00000000
>>
>> hmmm, clock disabled... dwc3-omap shouldn't have pm runtime at all.
>
> It does for the interconnect target module clkctrl register via PM
> runtime. That's the "usb_otg_ss" module.
>
>>> ...
>>> PC is at dwc3_omap_interrupt_thread+0x20/0x80
>>> LR is at irq_thread_fn+0x1c/0x54
>>> ...
>>> [<c0989fa8>] (dwc3_omap_interrupt_thread) from [<c038a4d8>]
>>> (irq_thread_fn+0x1c/0x54)
>>> [<c038a4d8>] (irq_thread_fn) from [<c038a7b0>] (irq_thread+0x12c/0x1f0)
>>> [<c038a7b0>] (irq_thread) from [<c035d6f0>] (kthread+0xdc/0xf4)
>>> [<c035d6f0>] (kthread) from [<c0307d78>] (ret_from_fork+0x14/0x3c)
>>> ...
>>>
>>> Unable to handle kernel paging request at virtual address ffffffec
>>> ...
>>> Internal error: Oops: 37 [#2] SMP ARM
>>> PC is at kthread_data+0x4/0xc
>>> LR is at irq_thread_dtor+0x28/0xd0
>>> ...
>>> [<c035e0b4>] (kthread_data) from [<c038a5dc>] (irq_thread_dtor+0x28/0xd0)
>>> [<c038a5dc>] (irq_thread_dtor) from [<c035bef0>] (task_work_run+0xb8/0xdc)
>>> [<c035bef0>] (task_work_run) from [<c03448d4>] (do_exit+0x314/0xa20)
>>> [<c03448d4>] (do_exit) from [<c030bea8>] (die+0x410/0x474)
>>> [<c030bea8>] (die) from [<c0301350>] (do_DataAbort+0xb4/0xb8)
>>> [<c0301350>] (do_DataAbort) from [<c030c578>] (__dabt_svc+0x58/0x80)
>>> Exception stack(0xee777ec8 to 0xee777f10)
>>> 7ec0: 0000014d ee6e6f10 00000034 fc020034 ee6e6f10 ee1eec00
>>> 7ee0: 00000000 00000000 ee6ec640 c038a4bc 00000000 00000000 00000000 ee777f18
>>> 7f00: c038a4d8 c0989fa8 60000013 ffffffff
>>> [<c030c578>] (__dabt_svc) from [<c0989fa8>] (dwc3_omap_interrupt_thread+0x20/0x80)
>>> [<c0989fa8>] (dwc3_omap_interrupt_thread) from [<c038a4d8>] (irq_thread_fn+0x1c/0x54)
>>> [<c038a4d8>] (irq_thread_fn) from [<c038a7b0>] (irq_thread+0x12c/0x1f0)
>>> [<c038a7b0>] (irq_thread) from [<c035d6f0>] (kthread+0xdc/0xf4)
>>> [<c035d6f0>] (kthread) from [<c0307d78>] (ret_from_fork+0x14/0x3c)
>>>
>>> Fix the issue by making sure the dwc3 interrupts are disabled
>>> before we call devm_request_threaded_irq().
>>
>> that should already be the case. Are you sure that register isn't zero
>> in probe?
>
> Looks like irq0_status = 0 and irqmisc_status = 0x2121. Also just
> clearing irqmisc with dwc3_omap_write_irqmisc_clr(omap, 0xffffffff)
> stops the issue from happening.
>
> There is some deferred probing happening but irqmisc is always 0x2121.
>
My assumption is that you have race here between IRQ handler and PM runtime
in error handling path during deferred probing.
Will below change fix issue for you?
diff --git a/drivers/usb/dwc3/dwc3-omap.c b/drivers/usb/dwc3/dwc3-omap.c
index 29e80cc..dbc21bc 100644
--- a/drivers/usb/dwc3/dwc3-omap.c
+++ b/drivers/usb/dwc3/dwc3-omap.c
@@ -517,12 +517,12 @@ static int dwc3_omap_probe(struct platform_device *pdev)
if (ret) {
dev_err(dev, "failed to request IRQ #%d --> %d\n",
omap->irq, ret);
- goto err1;
+ goto err11;
}
ret = dwc3_omap_extcon_register(omap);
if (ret < 0)
- goto err1;
+ goto err11;
ret = of_platform_populate(node, NULL, NULL, dev);
if (ret) {
@@ -538,6 +538,8 @@ static int dwc3_omap_probe(struct platform_device *pdev)
extcon_unregister_notifier(omap->edev, EXTCON_USB, &omap->vbus_nb);
extcon_unregister_notifier(omap->edev, EXTCON_USB_HOST, &omap->id_nb);
+err11:
+ disable_irq(omap->irq);
err1:
pm_runtime_put_sync(dev);
pm_runtime_disable(dev);
--
regards,
-grygorii
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