linux-kernel - Re: [PATCH v2 3/4] pinctrl: qcom: Add msmgpio irqchip flags

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Date:   Wed, 27 May 2020 18:00:57 +0530
From:   Maulik Shah <mkshah@...eaurora.org>
To:     Stephen Boyd <swboyd@...omium.org>, bjorn.andersson@...aro.org,
        evgreen@...omium.org, linus.walleij@...aro.org, maz@...nel.org,
        mka@...omium.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-gpio@...r.kernel.org, agross@...nel.org, tglx@...utronix.de,
        jason@...edaemon.net, dianders@...omium.org, rnayak@...eaurora.org,
        ilina@...eaurora.org, lsrao@...eaurora.org
Subject: Re: [PATCH v2 3/4] pinctrl: qcom: Add msmgpio irqchip flags

Hi,

On 5/27/2020 3:17 PM, Stephen Boyd wrote:
> Quoting Maulik Shah (2020-05-23 10:11:12)
>> Add irqchip specific flags for msmgpio irqchip to mask non wakeirqs
>> during suspend and mask before setting irq type.
> Why do we need to mask before setting irq type? Does something go wrong?
> Can you explain in the commit text?

i don't think anything goes wrong but there might be a case where some 
driver changing type at runtime,

masking before changing type should make sure any spurious interrupt is 
not detected during this operation.

>
>> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
> Does this need a Fixes tag?
Thanks i will add.
>
>> ---
>>   drivers/pinctrl/qcom/pinctrl-msm.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
>> index 2419023..b909ffe 100644
>> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
>> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
>> @@ -1143,6 +1143,8 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
>>          pctrl->irq_chip.irq_release_resources = msm_gpio_irq_relres;
>>          pctrl->irq_chip.irq_set_affinity = msm_gpio_irq_set_affinity;
>>          pctrl->irq_chip.irq_set_vcpu_affinity = msm_gpio_irq_set_vcpu_affinity;
>> +       pctrl->irq_chip.flags = IRQCHIP_MASK_ON_SUSPEND
> This is sort of sad. We have to set the IRQCHIP_MASK_ON_SUSPEND flag
> here so that genirq can call the mask op during suspend for the parent
> irqchip (pdc)?
During suspend, suspend_device_irq() will check this flag in msmgpio 
irqchip and then call it to mask if its not marked for wakeup.

in this case, setting this flag will call first invoke gpiolib's 
callback  (we override in first patch of this series), then it goes to 
msmgpio chip's mask callback,

this call will then get forwarded to its parent PDC and then to PDC's 
parent GIC.

This seems the way hierarchical irqchip works. i don't see any issue 
with this.
> Is there some way to not need to do that and instead let
> genirq do mask on suspend at the chip level instead of the irq level?
>
>> +                               | IRQCHIP_SET_TYPE_MASKED;
>>   
>>          np = of_parse_phandle(pctrl->dev->of_node, "wakeup-parent", 0);
>>          if (np) {

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