linux-kernel - Re: [PATCH] soc: brcmstb: Only register SoC device on STB platforms

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Message-ID: <20180112125828.GB19999@ulmo>
Date:   Fri, 12 Jan 2018 13:58:28 +0100
From:   Thierry Reding <thierry.reding@...il.com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     Brian Norris <computersforpeace@...il.com>,
        Gregory Fong <gregory.0xf0@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>, arm@...nel.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] soc: brcmstb: Only register SoC device on STB platforms

On Fri, Jan 12, 2018 at 12:12:11PM +0000, Sudeep Holla wrote:
> 
> 
> On 12/01/18 11:39, Sudeep Holla wrote:
> > 
> > 
> > On 09/01/18 14:54, Thierry Reding wrote:
> >> From: Thierry Reding <treding@...dia.com>
> >>
> >> After moving the SoC device initialization to an early initcall in
> >> commit f780429adfbc ("soc: brcmstb: biuctrl: Move to early_initcall"),
> >> the Broadcom STB SoC device is registered on all platforms if support
> >> for the device is enabled in the kernel configuration.
> >>
> >> This causes an additional SoC device to appear on platforms that already
> >> register a native one. In case of Tegra the STB SoC device is registered
> >> as soc0 (with totally meaningless content in the sysfs attributes) and
> >> causes various scripts and programs to fail because they don't know how
> >> to parse that data.
> >>
> >> To fix this, duplicate the check from brcmstb_soc_device_early_init()
> >> that already prevents the code from doing anything nonsensical on non-
> >> STB platforms.
> >>
> >> Fixes: f780429adfbc ("soc: brcmstb: biuctrl: Move to early_initcall")
> >> Signed-off-by: Thierry Reding <treding@...dia.com>
> >> ---
> >>  drivers/soc/bcm/brcmstb/common.c | 5 +++++
> >>  1 file changed, 5 insertions(+)
> >>
> >> diff --git a/drivers/soc/bcm/brcmstb/common.c b/drivers/soc/bcm/brcmstb/common.c
> >> index 781ada62d0a3..4fe1cb73b39a 100644
> >> --- a/drivers/soc/bcm/brcmstb/common.c
> >> +++ b/drivers/soc/bcm/brcmstb/common.c
> >> @@ -89,8 +89,13 @@ early_initcall(brcmstb_soc_device_early_init);
> >>  static int __init brcmstb_soc_device_init(void)
> >>  {
> >>  	struct soc_device_attribute *soc_dev_attr;
> >> +	struct device_node *sun_top_ctrl;
> >>  	struct soc_device *soc_dev;
> >>  
> >> +	sun_top_ctrl = of_find_matching_node(NULL, sun_top_ctrl_match);
> >> +	if (!sun_top_ctrl)
> >> +		return -ENODEV;
> >> +
> > 
> > missing of_node_put(sun_top_ctrl) ? or am I missing to see that elsewhere ?
> > 
> 
> Further, I still the error messags on my Juno with this patch applied. I
> fail to see how this patch prevents brcmstb_biuctrl_init which is
> early_initcall in drivers/soc/bcm/brcmstb/biuctrl.c getting called ?

I'm not sure I understand. There's no way we can prevent the early
initcall from running. The point here is to prevent it from running code
that shouldn't be run on a platform.

That said, perhaps an even better thing would be to return 0 in order to
avoid marking this as failure, since it really isn't an error if this
happens.

Thierry

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