linux-kernel - Re: [PATCH] pinctrl: qcom: spmi-gpio: make the irqchip immutable

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Message-ID: <d8912a0d811b5eb924b8c4136b099f72@kernel.org>
Date:   Wed, 13 Jul 2022 12:47:33 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Robert Marko <robimarko@...il.com>
Cc:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-gpio@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pinctrl: qcom: spmi-gpio: make the irqchip immutable

On 2022-07-13 12:08, Robert Marko wrote:
> On Tue, 12 Jul 2022 at 17:12, Marc Zyngier <maz@...nel.org> wrote:
>> 
>> On Tue, 12 Jul 2022 13:44:45 +0100,
>> Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org> wrote:
>> >
>> > On Tue, Jul 12, 2022 at 11:42:32AM +0100, Marc Zyngier wrote:
>> > > On Fri, 24 Jun 2022 20:51:12 +0100,
>> > > Robert Marko <robimarko@...il.com> wrote:
>> > > >
>> > > > Commit 6c846d026d49 ("gpio: Don't fiddle with irqchips marked as
>> > > > immutable") added a warning to indicate if the gpiolib is altering the
>> > > > internals of irqchips.
>> > > >
>> > > > Following this change the following warning is now observed for the SPMI
>> > > > PMIC pinctrl driver:
>> > > > gpio gpiochip1: (200f000.spmi:pmic@0:gpio@...0): not an immutable chip, please consider fixing it!
>> > > >
>> > > > Fix this by making the irqchip in the SPMI PMIC pinctrl driver immutable.
>> > > >
>> > > > Signed-off-by: Robert Marko <robimarko@...il.com>
>> > > > ---
>> > > >  drivers/pinctrl/qcom/pinctrl-spmi-gpio.c | 22 ++++++++++++----------
>> > > >  1 file changed, 12 insertions(+), 10 deletions(-)
>> > > >
>> > > > diff --git a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>> > > > index c3255b0bece4..406ee0933d0b 100644
>> > > > --- a/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>> > > > +++ b/drivers/pinctrl/qcom/pinctrl-spmi-gpio.c
>> > > > @@ -171,7 +171,6 @@ struct pmic_gpio_state {
>> > > >   struct regmap   *map;
>> > > >   struct pinctrl_dev *ctrl;
>> > > >   struct gpio_chip chip;
>> > > > - struct irq_chip irq;
>> > > >   u8 usid;
>> > > >   u8 pid_base;
>> > > >  };
>> > > > @@ -988,6 +987,17 @@ static void *pmic_gpio_populate_parent_fwspec(struct gpio_chip *chip,
>> > > >   return fwspec;
>> > > >  }
>> > > >
>> > > > +static const struct irq_chip spmi_gpio_irq_chip = {
>> > > > + .name           = "spmi-gpio",
>> > > > + .irq_ack        = irq_chip_ack_parent,
>> > > > + .irq_mask       = irq_chip_mask_parent,
>> > > > + .irq_unmask     = irq_chip_unmask_parent,
>> > >
>> > > No, this is wrong. Please look at the documentation to see how you
>> > > must now directly call into the gpiolib helpers for these two
>> > > callbacks.
>> > >
>> >
>> > IIUC, you are referring to gpiochip_disable_irq() and
>> > gpiochip_enable_irq() APIs.
>> 
>> I am indeed.
>> 
>> > These APIs are supposed to let the gpiolib know about that the IRQ
>> > usage of these GPIOs. But for the case of hierarchial IRQ domain,
>> > isn't the parent is going to do that?
>> 
>> Why would it? The parent has no clue about what sits above it. In a
>> hierarchical configuration, each level is responsible for its own
>> level, and the GPIO layer should be responsible for its own
>> management.
>> 
>> > Please correct me if I'm wrong.
>> 
>> I'm afraid you are, and this patch is a fairly obvious change in
>> behaviour, as the callbacks you mention above are not called anymore,
>> while they were before.
>> 
>> If they are not necessary (for reasons I can't fathom), then this
>> should be clearly explained.
> 
> Hi Marc,
> I will look at IRQ GPIO docs, but in this case, then we have more
> conversions that
> are not correct.

Then please point them out.

         M.
-- 
Jazz is not dead. It just smells funny...