linux-kernel - Re: [PATCH v2 04/91] firmware: rpi: Only create clocks device if we don't have a node for it

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Message-ID: <4842d1b72192bb7c461a2d50c8798f178da964e0.camel@suse.de>
Date:   Mon, 27 Apr 2020 13:24:14 +0200
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Maxime Ripard <maxime@...no.tech>, Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org,
        linux-rpi-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>
Subject: Re: [PATCH v2 04/91] firmware: rpi: Only create clocks device if we
 don't have a node for it

Hi Maxime,

On Fri, 2020-04-24 at 17:33 +0200, Maxime Ripard wrote:
> The firmware clocks driver was previously probed through a platform_device
> created by the firmware driver.
> 
> Since we will now have a node for that clocks driver, we need to create the
> device only in the case where there's no node for it already.
> 
> Signed-off-by: Maxime Ripard <maxime@...no.tech>
> ---
>  drivers/firmware/raspberrypi.c | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
> index da26a584dca0..1874f41b007c 100644
> --- a/drivers/firmware/raspberrypi.c
> +++ b/drivers/firmware/raspberrypi.c
> @@ -210,6 +210,15 @@ rpi_register_hwmon_driver(struct device *dev, struct
> rpi_firmware *fw)
>  
>  static void rpi_register_clk_driver(struct device *dev)
>  {
> +	/*
> +	 * Earlier DTs don't have a node for the firmware clocks but
> +	 * rely on us creating a platform device by hand. If we do
> +	 * have a node for the firmware clocks, just bail out here.
> +	 */
> +	if (of_get_compatible_child(dev->of_node,
> +				    "raspberrypi,firmware-clocks"))
> +		return;
> +
>  	rpi_clk = platform_device_register_data(dev, "raspberrypi-clk",
>  						-1, NULL, 0);
>  }
> @@ -262,8 +271,12 @@ static int rpi_firmware_remove(struct platform_device
> *pdev)
>  
>  	platform_device_unregister(rpi_hwmon);
>  	rpi_hwmon = NULL;
> -	platform_device_unregister(rpi_clk);
> -	rpi_clk = NULL;
> +
> +	if (rpi_clk) {

rpi_clk, being a static global variable, will be zeroed by default. So, if you
don't register the platform device, rpi_clk is going to be NULL, which you're
allowed to feed platform_device_unregister(), so no need to be extra careful.

Regards,
Nicolas

> +		platform_device_unregister(rpi_clk);
> +		rpi_clk = NULL;
> +	}
> +
>  	mbox_free_channel(fw->chan);
>  
>  	return 0;


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