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From: Linus Walleij <linus.walleij@linaro.org>
To: Mars Cheng <mars.cheng@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
	Rob Herring <robh@kernel.org>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Stephen Boyd <sboyd@kernel.org>, Sean Wang <sean.wang@kernel.org>,
	CC Hwang <cc.hwang@mediatek.com>,
	Loda Chou <loda.chou@mediatek.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@lists.infradead.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
	wsd_upstream@mediatek.com, mtk01761 <wendell.lin@mediatek.com>,
	linux-clk <linux-clk@vger.kernel.org>
Subject: Re: [PATCH v2 05/11] pinctrl: mediatek: avoid virtual gpio trying to set reg
Date: Fri, 23 Aug 2019 10:57:03 +0200
Message-ID: <CACRpkdZa_sQgvWC3ic0NxrVi9gS1cNTsV-wa-SDpA0e5kutBRw@mail.gmail.com> (raw)
In-Reply-To: <1566206502-4347-6-git-send-email-mars.cheng@mediatek.com>

On Mon, Aug 19, 2019 at 11:22 AM Mars Cheng <mars.cheng@mediatek.com> wrote:

> for virtual gpios, they should not do reg setting and
> should behave as expected for eint function.
>
> Signed-off-by: Mars Cheng <mars.cheng@mediatek.com>

This does not explain what a "virtual GPIO" is in this
context, so please elaborate. What is this? Why does
it exist? What is it used for?

GPIO is "general purpose input/output" and it is a
pretty rubbery category already as it is, so we need
to define our terms pretty strictly.

> +bool mtk_is_virt_gpio(struct mtk_pinctrl *hw, unsigned int gpio_n)
> +{
> +       const struct mtk_pin_desc *desc;
> +       bool virt_gpio = false;
> +
> +       if (gpio_n >= hw->soc->npins)
> +               return virt_gpio;
> +
> +       desc = (const struct mtk_pin_desc *)&hw->soc->pins[gpio_n];
> +
> +       if (desc->funcs &&
> +           desc->funcs[desc->eint.eint_m].name == 0)

NULL check is done like this:

if (desc->funcs && !desc->funcs[desc->eint.eint_m].name)

> +               virt_gpio = true;

So why is this GPIO "virtual" because it does not have
a name in the funcs table?

> @@ -278,6 +295,9 @@ static int mtk_xt_set_gpio_as_eint(void *data, unsigned long eint_n)
>         if (err)
>                 return err;
>
> +       if (mtk_is_virt_gpio(hw, gpio_n))
> +               return 0;

So does this mean we always succeed in setting a GPIO as eint
if it is virtual? Why? Explanatory comment is needed.

> @@ -693,6 +693,9 @@ static int mtk_gpio_get_direction(struct gpio_chip *chip, unsigned int gpio)
>         const struct mtk_pin_desc *desc;
>         int value, err;
>
> +       if (mtk_is_virt_gpio(hw, gpio))
> +               return 1;

Why are "virtual GPIOs" always inputs?

Yours,
Linus Walleij

  reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-19  9:21 [PATCHv2 00/11] Add basic SoC Support for Mediatek MT6779 SoC Mars Cheng
2019-08-19  9:21 ` [PATCH v2 01/11] dt-bindings: mediatek: add support for mt6779 reference board Mars Cheng
2019-08-23 15:50   ` Matthias Brugger
2019-08-19  9:21 ` [PATCH v2 02/11] dt-bindings: mtk-uart: add mt6779 uart bindings Mars Cheng
2019-08-23 15:47   ` Matthias Brugger
2019-08-19  9:21 ` [PATCH v2 03/11] dt-bindings: irq: mtk,sysirq: add support for mt6779 Mars Cheng
2019-08-23  8:51   ` Linus Walleij
2019-08-23 15:51     ` Matthias Brugger
2019-08-23 15:44   ` Matthias Brugger
2019-08-27 16:50   ` Rob Herring
2019-08-19  9:21 ` [PATCH v2 04/11] pinctrl: mediatek: update pinmux definitions " Mars Cheng
2019-08-23 15:53   ` Matthias Brugger
2019-08-19  9:21 ` [PATCH v2 05/11] pinctrl: mediatek: avoid virtual gpio trying to set reg Mars Cheng
2019-08-23  8:57   ` Linus Walleij [this message]
2019-08-19  9:21 ` [PATCH v2 06/11] pinctrl: mediatek: add pinctrl support for MT6779 SoC Mars Cheng
     [not found]   ` <CAGp9LzoVwNxY8Q3G4hxpa7=orsEox+J0mNamag70wyjrGvDiZw@mail.gmail.com>
2019-08-23  8:59     ` Linus Walleij
2019-08-19  9:21 ` [PATCH v2 07/11] pinctrl: mediatek: add mt6779 eint support Mars Cheng
2019-08-22 18:13   ` Sean Wang
2019-08-19  9:21 ` [PATCH v2 08/11] dt-bindings: mediatek: bindings for MT6779 clk Mars Cheng
2019-08-27 16:52   ` Rob Herring
2019-09-10 14:53   ` Stephen Boyd
2019-08-19  9:21 ` [PATCH v2 09/11] clk: mediatek: Add dt-bindings for MT6779 clocks Mars Cheng
2019-08-27 16:53   ` Rob Herring
2019-09-10 14:53   ` Stephen Boyd
2019-08-19  9:21 ` [PATCH v2 10/11] clk: mediatek: Add MT6779 clock support Mars Cheng
2019-09-10 14:53   ` Stephen Boyd
2019-08-19  9:21 ` [PATCH v2 11/11] arm64: dts: add dts nodes for MT6779 Mars Cheng
2019-08-19  9:40   ` Marc Zyngier
2019-08-19 11:42     ` Mars Cheng
2019-08-19 12:07       ` Marc Zyngier
2019-08-22  0:46         ` Mars Cheng
2019-08-23 16:13   ` Matthias Brugger

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