linux-kernel - Re: [PATCH v1 2/4] gpio: dwapb: Read GPIO base from gpio-base property

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Message-ID: <20210802135839.4clqd34npppwasyh@mobilestation>
Date:   Mon, 2 Aug 2021 16:58:39 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>, linux-kernel@...r.kernel.org,
        linux-gpio@...r.kernel.org,
        Hoan Tran <hoan@...amperecomputing.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: Re: [PATCH v1 2/4] gpio: dwapb: Read GPIO base from gpio-base
 property

+Cc Rob

On Mon, Jul 26, 2021 at 03:54:34PM +0300, Andy Shevchenko wrote:
> For backward compatibility with some legacy devices introduce
> a new (*) property gpio-base to read GPIO base. This will allow
> further cleanup of the driver.
> 
> *) Note, it's not new for GPIO library since mockup driver is
>    using it already.

You are right but I don't think it's a good idea to advertise the
pure Linux-internal property "gpio-base" to any use-case like OF
and ACPI FW nodes. Especially seeing we don't have it described in the
DT-bindings and noting that the mockup driver is dedicated for the
GPIO tests only. What about restricting the property usage for the
SW-nodes only by adding an additional check: is_software_node() here?

@Linus, @Bartosz, @Rob, what do you think about that?

-Sergey

> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/gpio/gpio-dwapb.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
> index f6ae69d5d644..e3011d4e17b0 100644
> --- a/drivers/gpio/gpio-dwapb.c
> +++ b/drivers/gpio/gpio-dwapb.c
> @@ -581,7 +581,8 @@ static struct dwapb_platform_data *dwapb_gpio_get_pdata(struct device *dev)
>  			pp->ngpio = DWAPB_MAX_GPIOS;
>  		}
>  
> -		pp->gpio_base	= -1;
> +		if (fwnode_property_read_u32(fwnode, "gpio-base", &pp->gpio_base))
> +			pp->gpio_base = -1;
>  
>  		/*
>  		 * Only port A can provide interrupts in all configurations of
> -- 
> 2.30.2
>