linux-kernel - Re: [PATCH] drm/tegra: switch to using devm_gpiod_get

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Message-ID: <20190916135904.GA7488@ulmo>
Date:   Mon, 16 Sep 2019 15:59:04 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Dmitry Osipenko <digetx@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        dri-devel@...ts.freedesktop.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/tegra: switch to using devm_gpiod_get_optional

On Sun, Sep 15, 2019 at 12:13:23AM -0700, Dmitry Torokhov wrote:
> We do not really need to use API that fetches GPIO data from an
> arbitrary device tree node, as we are dealing with device tree node
> assigned to the device structure. We can easily switch to
> devm_gpiod_get_optional() plus gpiod_set_consumer_name() and clean up
> the code.
> 
> Note this is part of efforts to get rid of [devm_]gpiod_get_from_of_node
> in drivers so that gpiolib can be cleaned up.
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
>  drivers/gpu/drm/tegra/output.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)

We can't do that. There's a special case in rgb.c that sets
output->of_node to something different than output->dev, so we actually
need to pass the struct device_node * separately.

Thierry

> 
> diff --git a/drivers/gpu/drm/tegra/output.c b/drivers/gpu/drm/tegra/output.c
> index bdcaa4c7168c..b4248125b844 100644
> --- a/drivers/gpu/drm/tegra/output.c
> +++ b/drivers/gpu/drm/tegra/output.c
> @@ -121,19 +121,15 @@ int tegra_output_probe(struct tegra_output *output)
>  		of_node_put(ddc);
>  	}
>  
> -	output->hpd_gpio = devm_gpiod_get_from_of_node(output->dev,
> -						       output->of_node,
> -						       "nvidia,hpd-gpio", 0,
> -						       GPIOD_IN,
> -						       "HDMI hotplug detect");
> -	if (IS_ERR(output->hpd_gpio)) {
> -		if (PTR_ERR(output->hpd_gpio) != -ENOENT)
> -			return PTR_ERR(output->hpd_gpio);
> -
> -		output->hpd_gpio = NULL;
> -	}
> +	output->hpd_gpio = devm_gpiod_get_optional(output->dev,
> +						   "nvidia,hpd", GPIOD_IN);
> +	if (IS_ERR(output->hpd_gpio))
> +		return PTR_ERR(output->hpd_gpio);
>  
>  	if (output->hpd_gpio) {
> +		gpiod_set_consumer_name(output->hpd_gpio,
> +					"HDMI hotplug detect");
> +
>  		err = gpiod_to_irq(output->hpd_gpio);
>  		if (err < 0) {
>  			dev_err(output->dev, "gpiod_to_irq(): %d\n", err);
> -- 
> 2.23.0.237.gc6a4ce50a0-goog
> 
> 
> -- 
> Dmitry

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