linux-kernel - Re: [PATCH RFC v2 10/14] drivers: pinctrl: msm: setup GPIO chip in hierarchy

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Message-ID: <20191113183506.GA18786@codeaurora.org>
Date:   Wed, 13 Nov 2019 11:35:06 -0700
From:   Lina Iyer <ilina@...eaurora.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Stephen Boyd <swboyd@...omium.org>,
        Evan Green <evgreen@...omium.org>,
        Marc Zyngier <maz@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        MSM <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        mkshah@...eaurora.org,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH RFC v2 10/14] drivers: pinctrl: msm: setup GPIO chip in
 hierarchy

On Thu, Oct 03 2019 at 06:17 -0600, Linus Walleij wrote:
>On Fri, Sep 13, 2019 at 11:59 PM Lina Iyer <ilina@...eaurora.org> wrote:
>
>> Some GPIOs are marked as wakeup capable and are routed to another
>> interrupt controller that is an always-domain and can detect interrupts
>> even most of the SoC is powered off. The wakeup interrupt controller
>> wakes up the GIC and replays the interrupt at the GIC.
>>
>> Setup the TLMM irqchip in hierarchy with the wakeup interrupt controller
>> and ensure the wakeup GPIOs are handled correctly.
>>
>> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
>> Signed-off-by: Lina Iyer <ilina@...eaurora.org>
>> ----
>> Changes in RFC v2:
>>         - Define irq_domain_qcom_handle_wakeup()
>>         - Rebase on top of GPIO hierarchy support in linux-next
>>         - Set the chained irq handler for summary line
>
>This is looking better every time I look at it, it's really complex
>but alas the problem is hard to solve so it requires complex solutions.
>
>> @@ -1006,6 +1091,7 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
>>         struct gpio_irq_chip *girq;
>>         int ret;
>>         unsigned ngpio = pctrl->soc->ngpios;
>> +       struct device_node *dn;
>
>I usually call the variable "np"
>
Will change.

>> @@ -1021,17 +1107,40 @@ static int msm_gpio_init(struct msm_pinctrl *pctrl)
>>
>>         pctrl->irq_chip.name = "msmgpio";
>>         pctrl->irq_chip.irq_enable = msm_gpio_irq_enable;
>> +       pctrl->irq_chip.irq_disable = msm_gpio_irq_disable;
>>         pctrl->irq_chip.irq_mask = msm_gpio_irq_mask;
>>         pctrl->irq_chip.irq_unmask = msm_gpio_irq_unmask;
>>         pctrl->irq_chip.irq_ack = msm_gpio_irq_ack;
>> +       pctrl->irq_chip.irq_eoi = irq_chip_eoi_parent;
>
>This part and the functions called seem fine!
>
>> +       dn = of_parse_phandle(pctrl->dev->of_node, "wakeup-parent", 0);
>> +       if (dn) {
>> +               int i;
>> +               bool skip;
>> +               unsigned int gpio;
>> +
>> +               chip->irq.parent_domain = irq_find_matching_host(dn,
>> +                                                DOMAIN_BUS_WAKEUP);
>> +               of_node_put(dn);
>> +               if (!chip->irq.parent_domain)
>> +                       return -EPROBE_DEFER;
>> +               chip->irq.child_to_parent_hwirq = msm_gpio_wakeirq;
>> +
>> +               skip = irq_domain_qcom_handle_wakeup(chip->irq.parent_domain);
>> +               for (i = 0; skip && i < pctrl->soc->nwakeirq_map; i++) {
>> +                       gpio = pctrl->soc->wakeirq_map[i].gpio;
>> +                       set_bit(gpio, pctrl->skip_wake_irqs);
>> +               }
>> +       }
>
>OK I guess this is how we should do it, maybe add a comment to clarify
>that we are checking the parent irqdomain of the chained IRQ to see
>if we need to avoid disabling the irq as it is used for wakeup. (IIUC
>what the code does!)
>
Okay.

>> +       /*
>> +        * Since we are chained to the GIC using the TLMM summary line
>> +        * and in hierarchy with the wakeup parent interrupt controller,
>> +        * explicitly set the chained summary line. We need to do this because
>> +        * the summary line is not routed to the wakeup parent but directly
>> +        * to the GIC.
>> +        */
>> +       gpiochip_set_chained_irqchip(chip, &pctrl->irq_chip, pctrl->irq,
>> +                                    msm_gpio_irq_handler);
>
>I don't think this part is needed, we already have:
>
>girq->parent_handler = msm_gpio_irq_handler;
>girq->num_parents = 1;
>girq->parents = devm_kcalloc(pctrl->dev, 1, sizeof(*girq->parents),
>     GFP_KERNEL);
>if (!girq->parents)
>     return -ENOMEM;
>girq->default_type = IRQ_TYPE_NONE;
>girq->handler = handle_bad_irq;
>girq->parents[0] = pctrl->irq;
>
>This will make the irq chain when calling gpiochip_add_data(), so
>just delete this and see if everything works as before.
>
I thought it didn't work without this change and I am not sure why it
started working after I did. May be it was a bad set of patches that I
pulled in.

>Other than that it looks fine!
Thanks for your review.

--Lina