From: Lina Iyer <ilina@codeaurora.org>
To: Stephen Boyd <swboyd@chromium.org>
Cc: evgreen@chromium.org, linus.walleij@linaro.org,
marc.zyngier@arm.com, linux-kernel@vger.kernel.org,
linux-arm-msm@vger.kernel.org, bjorn.andersson@linaro.org,
mkshah@codeaurora.org, linux-gpio@vger.kernel.org,
rnayak@codeaurora.org
Subject: Re: [PATCH RFC 02/14] drivers: irqchip: pdc: Do not toggle IRQ_ENABLE during mask/unmask
Date: Fri, 20 Sep 2019 16:31:42 -0600 [thread overview]
Message-ID: <20190920223142.GI15853@codeaurora.org> (raw)
In-Reply-To: <5d85511e.1c69fb81.98f62.dae0@mx.google.com>
On Fri, Sep 20 2019 at 16:22 -0600, Stephen Boyd wrote:
>Quoting Lina Iyer (2019-09-11 09:15:57)
>> On Thu, Sep 05 2019 at 18:39 -0600, Stephen Boyd wrote:
>> >Quoting Lina Iyer (2019-08-29 11:11:51)
>> >> When an interrupt is to be serviced, the convention is to mask the
>> >> interrupt at the chip and unmask after servicing the interrupt. Enabling
>> >> and disabling the interrupt at the PDC irqchip causes an interrupt storm
>> >> due to the way dual edge interrupts are handled in hardware.
>> >>
>> >> Skip configuring the PDC when the IRQ is masked and unmasked, instead
>> >> use the irq_enable/irq_disable callbacks to toggle the IRQ_ENABLE
>> >> register at the PDC. The PDC's IRQ_ENABLE register is only used during
>> >> the monitoring mode when the system is asleep and is not needed for
>> >> active mode detection.
>> >
>> >I think this is saying that we want to always let the line be sent
>> >through the PDC to the parent irqchip, in this case GIC, so that we
>> >don't get an interrupt storm for dual edge interrupts? Why does dual
>> >edge interrupts cause a problem?
>> >
>> I am not sure about the hardware details, but the PDC designers did not
>> expect enable and disable to be called whenever the interrupt is
>> handled. This specially becomes a problem for dual edge interrupts which
>> seems to generate a interrupt storm when enabled/disabled while handling
>> the interrupt.
>>
>
>Ok. I just wanted to confirm that masking "doesn't matter" to the PDC
>because it assumes the irqchip closer to the CPU will be able to mask it
>anyway. Is that right?
>
That is correct.
next prev parent reply other threads:[~2019-09-20 22:31 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 18:11 [PATCH RFC 00/14] qcom: support wakeup capable GPIOs Lina Iyer
2019-08-29 18:11 ` [PATCH RFC 01/14] irqdomain: add bus token DOMAIN_BUS_WAKEUP Lina Iyer
2019-08-29 18:11 ` [PATCH RFC 02/14] drivers: irqchip: pdc: Do not toggle IRQ_ENABLE during mask/unmask Lina Iyer
2019-09-06 0:39 ` Stephen Boyd
2019-09-11 16:15 ` Lina Iyer
2019-09-20 22:22 ` Stephen Boyd
2019-09-20 22:31 ` Lina Iyer [this message]
2019-08-29 18:11 ` [PATCH RFC 03/14] drivers: irqchip: add PDC irqdomain for wakeup capable GPIOs Lina Iyer
2019-08-30 14:50 ` Marc Zyngier
2019-08-30 15:58 ` Lina Iyer
2019-09-02 8:21 ` Marc Zyngier
2019-09-03 22:51 ` Stephen Boyd
2019-08-29 18:11 ` [PATCH RFC 04/14] of: irq: document properties for wakeup interrupt parent Lina Iyer
2019-09-02 13:38 ` Rob Herring
2019-08-29 18:11 ` [PATCH RFC 05/14] dt-bindings/interrupt-controller: pdc: add SPI config register Lina Iyer
2019-09-02 13:38 ` Rob Herring
2019-09-02 13:53 ` Marc Zyngier
2019-09-03 17:07 ` Lina Iyer
2019-09-06 0:03 ` Stephen Boyd
2019-09-13 19:53 ` Lina Iyer
2019-09-17 21:50 ` Lina Iyer
2019-09-20 22:20 ` Stephen Boyd
2019-09-23 6:11 ` Sibi Sankar
[not found] ` <CACRpkdaReFzjb_hcDbQwqMX+whzscLpeZpJPHKqOo+9tANzemA@mail.gmail.com>
2019-09-11 15:19 ` Lina Iyer
2019-08-29 18:11 ` [PATCH RFC 06/14] drivers: irqchip: pdc: additionally set type in SPI config registers Lina Iyer
2019-09-06 0:22 ` Stephen Boyd
2019-08-29 18:11 ` [PATCH RFC 07/14] genirq: Introduce irq_chip_get/set_parent_state calls Lina Iyer
2019-09-06 0:35 ` Stephen Boyd
2019-08-29 18:11 ` [PATCH RFC 08/14] drivers: irqchip: pdc: Add irqchip set/get state calls Lina Iyer
2019-09-06 0:09 ` Stephen Boyd
2019-08-29 18:11 ` [PATCH RFC 09/14] drivers: pinctrl: msm: fix use of deprecated gpiolib APIs Lina Iyer
2019-09-06 0:11 ` Stephen Boyd
2019-09-11 10:19 ` Linus Walleij
2019-09-11 16:16 ` Lina Iyer
2019-08-29 18:11 ` [PATCH RFC 10/14] drivers: pinctrl: msm: setup GPIO chip in hierarchy Lina Iyer
2019-08-29 18:12 ` [PATCH RFC 11/14] drivers: pinctrl: sdm845: add PDC wakeup interrupt map for GPIOs Lina Iyer
2019-09-06 0:24 ` Stephen Boyd
2019-08-29 18:12 ` [PATCH RFC 12/14] arm64: dts: qcom: add PDC interrupt controller for SDM845 Lina Iyer
2019-09-09 11:26 ` Maulik Shah
2019-08-29 18:12 ` [PATCH RFC 13/14] arm64: dts: qcom: setup PDC as the wakeup parent for TLMM on SDM845 Lina Iyer
2019-08-29 18:12 ` [PATCH RFC 14/14] arm64: defconfig: enable PDC interrupt controller for Qualcomm SDM845 Lina Iyer
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