Messages in this thread | | | Subject | Re: [RESEND PATCH v1 3/9] spmi: pmic-arb: check apid against limits before calling irq handler | From | Fenglin Wu <> | Date | Fri, 15 Oct 2021 09:54:01 +0800 |
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On 10/15/2021 9:15 AM, Stephen Boyd wrote: > Quoting Fenglin Wu (2021-10-13 20:11:40) >> On 10/14/2021 3:25 AM, Stephen Boyd wrote: >>> Quoting Fenglin Wu (2021-10-12 22:31:22) >>>> On 10/13/2021 2:02 AM, Stephen Boyd wrote: >>>>> Quoting Fenglin Wu (2021-09-16 23:32:58) >>>>>> From: David Collins <collinsd@codeaurora.org> >>>>>> >>>>>> Check that the apid for an SPMI interrupt falls between the >>>>>> min_apid and max_apid that can be handled by the APPS processor >>>>>> before invoking the per-apid interrupt handler: >>>>>> periph_interrupt(). >>>>>> >>>>>> This avoids an access violation in rare cases where the status >>>>>> bit is set for an interrupt that is not owned by the APPS >>>>>> processor. >>>>>> >>>>>> Signed-off-by: David Collins <collinsd@codeaurora.org> >>>>>> Signed-off-by: Fenglin Wu <quic_fenglinw@quicinc.com> >>>>>> --- >>>>> Fixes? BTW, a lot of these patches are irqchip specific. It would be >>>>> good to get review from irqchip maintainers. Maybe we should split the >>>>> irqchip driver off via the auxiliary bus so that irqchip maintainers can >>>>> review. Please Cc them on irqchip related patches. >>>>> >>>>> IRQCHIP DRIVERS >>>>> M: Thomas Gleixner <tglx@linutronix.de> >>>>> M: Marc Zyngier <maz@kernel.org> >>>> Sure, copied Thomas and Marc for code review. >>>> This is a fix to avoid the register access violation in a case that an >>>> interrupt is fired in a PMIC module which is not owned by APPS >>>> processor. >>> Got it. >>> >>>>>> drivers/spmi/spmi-pmic-arb.c | 6 ++++++ >>>>>> 1 file changed, 6 insertions(+) >>>>>> >>>>>> diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c >>>>>> index 4d7ad004..c4adc06 100644 >>>>>> --- a/drivers/spmi/spmi-pmic-arb.c >>>>>> +++ b/drivers/spmi/spmi-pmic-arb.c >>>>>> @@ -535,6 +535,12 @@ static void pmic_arb_chained_irq(struct irq_desc *desc) >>>>>> id = ffs(status) - 1; >>>>>> status &= ~BIT(id); >>>>>> apid = id + i * 32; >>>>>> + if (apid < pmic_arb->min_apid >>>>>> + || apid > pmic_arb->max_apid) { >>>>> The || goes on the line above. What about making a local variable for >>>>> first and last and then shifting by 5 in the loop? >>>>> >>>>> int first = pmic_arb->min_apid; >>>>> int last = pmic_arb->max_apid; >>>>> >>>>> for (i = first >> 5; i <= last >> 5; i++) >>>>> >>>>> if (apid < first || apid > last) >>>> ACK, will update it following this. >>>>>> + WARN_ONCE(true, "spurious spmi irq received for apid=%d\n", >>>>>> + apid); >>>>> Is there any way to recover from this? Or once the mapping is wrong >>>>> we're going to get interrupts that we don't know what to do with >>>>> forever? >>>> This is a rare case that the unexpected interrupt is fired in a module >>>> not owned by APPS process, so the interrupt itself is not expected hence >>>> no need to recover from this but just bail out to avoid following register >>>> access violation. >>> And then the irq stops coming? It feels like a misconfiguration in the >>> firmware that we're trying to hide, hence the WARN_ONCE(). Can we >>> somehow silence irqs that aren't owned by the APPS when this driver >>> probes so that they can't even happen after probe? >> Actually this is a rarely happened case that couldn't be reproduced easily >> and consistently for further debug. I agreed this should be caused by HW >> misconfiguration or even some unknown HW bug that it would send out SPMI >> interrupt messages with incorrect APID, but we have never had any chance >> to find out the root cause. The patch here simply checked the APID and >> bail out if it's not in the valid range, it won't cause anything bad but >> improves the SW robustness. After that, the IRQ won't be triggered again >> because the latched status in PMIC is not cleared. Also, because of the >> access restriction to the registers corresponding to this APID, there is >> nothing we can do from APPS processor side to keep it silent. > This patch seems like a band-aid for an issue that isn't fully > understood. I suppose it's good that the irq will stay asserted forever > and then it won't happen again until it gets cleared by some other > processor in the SoC. Instead of the WARN_ONCE() can we track if any irq > is handled when the chained irq is raised, and if nothing is handled > then call handle_bad_irq() on the chained descriptor? Take a look at > pinctrl-msm.c to see how they handled spurious irqs that aren't actually > directed at the APPS processor. We should do something similar here. Sure, I will do it that way.
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