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

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Message-ID: <de6b302b-7368-72ff-6643-c585c2118050@arm.com>
Date:   Fri, 12 Jan 2018 15:25:54 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        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 12/01/18 13:15, Thierry Reding wrote:
> On Fri, Jan 12, 2018 at 01:58:28PM +0100, Thierry Reding wrote:
>> 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.
> 
> Oh, I see the errors you mentioned now. They're in the biuctrl code,
> which I hadn't noticed before since they don't cause any weird behaviour
> other than the error messages in the boot log. Let me fix that up while
> I'm on it.

Sorry for missing context. I posted a patch[1] to fix the error messages
I mentioned, but Florian directed me to his patch instead and hence the
above question was for him as your patch was addressing a different issue.

-- 
Regards,
Sudeep

[1] https://marc.info/?l=linux-kernel&m=151568158127806&w=2