linux-kernel - Re: [PATCH v3 3/3] memory: Add Broadcom STB memory controller driver

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Date:   Fri, 12 Aug 2022 10:52:50 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        linux-kernel@...r.kernel.org
Cc:     Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v3 3/3] memory: Add Broadcom STB memory controller driver

On 8/12/22 10:36, Krzysztof Kozlowski wrote:
> On 12/08/2022 20:29, Florian Fainelli wrote:
>> On 8/9/22 02:58, Krzysztof Kozlowski wrote:
>>> On 02/08/2022 01:09, Florian Fainelli wrote:
>>>> Add support for configuring the Self Refresh Power Down (SRPD)
>>>> inactivity timeout on Broadcom STB chips. This is used to conserve power
>>>> when the DRAM activity is reduced.
>>>>
>>>
>>>
>>>> +static int __maybe_unused brcmstb_memc_resume(struct device *dev)
>>>> +{
>>>> +	struct brcmstb_memc *memc = dev_get_drvdata(dev);
>>>> +
>>>> +	if (memc->timeout_cycles == 0)
>>>> +		return 0;
>>>> +
>>>> +	return brcmstb_memc_srpd_config(memc, memc->timeout_cycles);
>>>> +}
>>>> +
>>>> +static SIMPLE_DEV_PM_OPS(brcmstb_memc_pm_ops, brcmstb_memc_suspend,
>>>> +			 brcmstb_memc_resume);
>>>> +
>>>> +static struct platform_driver brcmstb_memc_driver = {
>>>> +	.probe = brcmstb_memc_probe,
>>>> +	.remove = brcmstb_memc_remove,
>>>> +	.driver = {
>>>> +		.name		= "brcmstb_memc",
>>>> +		.owner		= THIS_MODULE,
>>>
>>> No need, run coccinelle.
>>>
>>>> +		.of_match_table	= brcmstb_memc_of_match,
>>>> +		.pm		= &brcmstb_memc_pm_ops,
>>>
>>> Shouldn't this be pm_ptr()? and then no need for __maybe_unused in
>>> brcmstb_memc_resume/suspend.
>>
>> How can one can remove __maybe_unused without causing a warning for the
>> CONFIG_PM=n case, not that I needed to build to convince myself, but
>> still did anyway:
>>
>> drivers/memory/brcmstb_memc.c:275:12: warning: 'brcmstb_memc_resume'
>> defined but not used [-Wunused-function]
>>    static int brcmstb_memc_resume(struct device *dev)
>>               ^~~~~~~~~~~~~~~~~~~
>> drivers/memory/brcmstb_memc.c:252:12: warning: 'brcmstb_memc_suspend'
>> defined but not used [-Wunused-function]
>>    static int brcmstb_memc_suspend(struct device *dev)
>>               ^~~~~~~~~~~~~~~~~~~~
>>
>> unless you also implied enclosing those functions under an #if
>> IS_ENABLED(CONFIG_PM) or something which is IMHO less preferable.
> 
> Are you sure you added also pm_ptr()? I don't see such warnings with W=1
> and final object does not have the functions (for a different driver but
> same principle).

Yes I am sure I added pm_ptr() see the v4 I just submitted. I don't see 
how the compiler cannot warn about the functions being unused the day 
they stop being referenced by the pm_ops structure which is eliminated?
-- 
Florian