linux-kernel - Re: [PATCH v2 1/7] arm/virt: place power button pin number on a define

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Message-ID: <CAFEAcA_4ioaV2Rg8dFFUeAU=tBBq=_TRVpCAUftMeDxu9=gDTg@mail.gmail.com>
Date: Thu, 18 Jul 2024 11:33:41 +0100
From: Peter Maydell <peter.maydell@...aro.org>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>, "Michael S. Tsirkin" <mst@...hat.com>, 
	Shiju Jose <shiju.jose@...wei.com>, Ani Sinha <anisinha@...hat.com>, 
	Igor Mammedov <imammedo@...hat.com>, Shannon Zhao <shannon.zhaosl@...il.com>, 
	linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org, qemu-arm@...gnu.org, 
	qemu-devel@...gnu.org
Subject: Re: [PATCH v2 1/7] arm/virt: place power button pin number on a define

On Fri, 12 Jul 2024 at 14:15, 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>
> ---
>  hw/arm/virt-acpi-build.c | 6 +++---
>  hw/arm/virt.c            | 3 ++-
>  include/hw/arm/virt.h    | 3 +++
>  3 files changed, 8 insertions(+), 4 deletions(-)

Thanks for writing this refactoring patch; I have a couple
of nits below but otherwise it looks good.

> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index e10cad86dd73..ad0a0bcec310 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -154,10 +154,10 @@ static void acpi_dsdt_add_gpio(Aml *scope, const MemMapEntry *gpio_memmap,
>      aml_append(dev, aml_name_decl("_CRS", crs));
>
>      Aml *aei = aml_resource_template();
> -    /* Pin 3 for power button */
> -    const uint32_t pin_list[1] = {3};
> +    /* Pin for power button */
> +    const uint32_t pin = GPIO_PIN_POWER_BUTTON;

I would say that with the constant name we could now drop that
comment entirely.

>      aml_append(aei, aml_gpio_int(AML_CONSUMER, AML_EDGE, AML_ACTIVE_HIGH,
> -                                 AML_EXCLUSIVE, AML_PULL_UP, 0, pin_list, 1,
> +                                 AML_EXCLUSIVE, AML_PULL_UP, 0, &pin, 1,
>                                   "GPO0", NULL, 0));
>      aml_append(dev, aml_name_decl("_AEI", aei));
>
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index b0c68d66a345..7b886f3477b6 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1013,7 +1013,8 @@ static void create_gpio_keys(char *fdt, DeviceState *pl061_dev,
>                               uint32_t phandle)
>  {
>      gpio_key_dev = sysbus_create_simple("gpio-key", -1,
> -                                        qdev_get_gpio_in(pl061_dev, 3));
> +                                        qdev_get_gpio_in(pl061_dev,
> +                                                         GPIO_PIN_POWER_BUTTON));
>
>      qemu_fdt_add_subnode(fdt, "/gpio-keys");
>      qemu_fdt_setprop_string(fdt, "/gpio-keys", "compatible", "gpio-keys");

You've missed one instance of the hardcoded 3, where we write the
FDT information about it
further down in this function:

    qemu_fdt_setprop_cells(fdt, "/gpio-keys/poweroff",
                           "gpios", phandle, 3, 0);

This also can now be GPIO_PIN_POWER_BUTTON.

thanks
-- PMM