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: <20200428135041.zg5h454fkc5wgxp3@gilmour.lan>
Date:   Tue, 28 Apr 2020 15:50:41 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Cc:     Eric Anholt <eric@...olt.net>, 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 Nicolas,

On Mon, Apr 27, 2020 at 01:24:14PM +0200, Nicolas Saenz Julienne wrote:
> 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.

Indeed, I'll fix that up.

Thanks!
Maxime

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