linux-kernel - Re: [PATCH v3 1/7] arm/virt: place power button pin number on a define

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Message-ID: <20240730132620.46cca4ce@imammedo.users.ipa.redhat.com>
Date: Tue, 30 Jul 2024 13:26:20 +0200
From: Igor Mammedov <imammedo@...hat.com>
To: Peter Maydell <peter.maydell@...aro.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, Jonathan Cameron
 <Jonathan.Cameron@...wei.com>, Shiju Jose <shiju.jose@...wei.com>, "Michael
 S. Tsirkin" <mst@...hat.com>, Ani Sinha <anisinha@...hat.com>, Shannon Zhao
 <shannon.zhaosl@...il.com>, linux-kernel@...r.kernel.org,
 qemu-arm@...gnu.org, qemu-devel@...gnu.org
Subject: Re: [PATCH v3 1/7] arm/virt: place power button pin number on a
 define

On Tue, 30 Jul 2024 09:29:37 +0100
Peter Maydell <peter.maydell@...aro.org> wrote:

> On Tue, 30 Jul 2024 at 08:26, Igor Mammedov <imammedo@...hat.com> wrote:
> >
> > On Mon, 22 Jul 2024 08:45:53 +0200
> > Mauro Carvalho Chehab <mchehab+huawei@...nel.org> wrote:
> >  
> > > Having magic numbers inside the code is not a good idea, as it
> > > is error-prone. So, instead, create a macro with the number
> > > definition.
> > >
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> > > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>  
> 
> > > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > > index b0c68d66a345..c99c8b1713c6 100644
> > > --- a/hw/arm/virt.c
> > > +++ b/hw/arm/virt.c
> > > @@ -1004,7 +1004,7 @@ static void virt_powerdown_req(Notifier *n, void *opaque)
> > >      if (s->acpi_dev) {
> > >          acpi_send_event(s->acpi_dev, ACPI_POWER_DOWN_STATUS);
> > >      } else {
> > > -        /* use gpio Pin 3 for power button event */
> > > +        /* use gpio Pin for power button event */
> > >          qemu_set_irq(qdev_get_gpio_in(gpio_key_dev, 0), 1);  
> >
> > /me confused, it was saying Pin 3 but is passing 0 as argument where as elsewhere
> > you are passing 3. Is this a bug?  
> 
> No. The gpio_key_dev is a gpio-key device which has one
> input (which you assert to "press the key") and one output,
> which goes high when the key is pressed and then falls
> 100ms later. The virt board wires up the output of the
> gpio-key device to input 3 on the PL061 GPIO controller.
> (This happens in create_gpio_keys().) So the code is correct
> to assert input 0 on the gpio-key device and the comment
> isn't wrong that this results in GPIO pin 3 being asserted:
> the link is just indirect.

it's likely obvious to ARM folks, but maybe comment should
clarify above for unaware.
 
> 
> thanks
> -- PMM
>