linux-kernel - Re: [PATCH V2 6/7] coresight: stm: Move ACPI support from AMBA driver to platform driver

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Date:   Mon, 4 Dec 2023 13:17:10 +0000
From:   James Clark <james.clark@....com>
To:     Anshuman Khandual <anshuman.khandual@....com>,
        linux-arm-kernel@...ts.infradead.org, suzuki.poulose@....com,
        Sudeep Holla <Sudeep.Holla@....com>
Cc:     Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Mike Leach <mike.leach@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        coresight@...ts.linaro.org,
        linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH V2 6/7] coresight: stm: Move ACPI support from AMBA driver
 to platform driver



On 04/12/2023 11:50, Anshuman Khandual wrote:
> 
> 
> On 12/4/23 15:53, James Clark wrote:
>>
>>
>> On 01/12/2023 06:20, Anshuman Khandual wrote:
>>> Add support for the stm devices in the platform driver, which can then be
>>> used on ACPI based platforms. This change would now allow runtime power
>>> management for ACPI based systems. The driver would try to enable the APB
>>> clock if available.
>>>
>>> Cc: Lorenzo Pieralisi <lpieralisi@...nel.org>
>>> Cc: Sudeep Holla <sudeep.holla@....com>
>>> Cc: Suzuki K Poulose <suzuki.poulose@....com>
>>> Cc: Mike Leach <mike.leach@...aro.org>
>>> Cc: James Clark <james.clark@....com>
>>> Cc: Maxime Coquelin <mcoquelin.stm32@...il.com>
>>> Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>
>>> Cc: linux-acpi@...r.kernel.org
>>> Cc: linux-arm-kernel@...ts.infradead.org
>>> Cc: linux-kernel@...r.kernel.org
>>> Cc: coresight@...ts.linaro.org
>>> Cc: linux-stm32@...md-mailman.stormreply.com
>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
>>> ---
>> [...]
>>>  
>>> -module_amba_driver(stm_driver);
>>> +static int stm_platform_probe(struct platform_device *pdev)
>>> +{
>>> +	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> +	int ret = 0;
>>> +
>>> +	pm_runtime_get_noresume(&pdev->dev);
>>> +	pm_runtime_set_active(&pdev->dev);
>>> +	pm_runtime_enable(&pdev->dev);
>>> +
>>> +	ret = __stm_probe(&pdev->dev, res, NULL);
>>
>> Very minor nit, but this used to print this:
>>
>>   coresight stm0: STM500 initialized
>>
>> And now it prints this:
>>
>>   coresight stm0: (null) initialized
>>
>> (null) kind of makes it look a little bit like something has gone wrong.
>> Maybe we could just put "initialised" if you don't have a string from ACPI?
> 
> __stm_probe() gets called from both AMBA and platform driver paths. Even though
> a NULL check inside dev_info(..."%s initialized\n",...) could be added, but how
> to differentiate it from a scenario when coresight_get_uci_data() returns NULL ?

Sudeep's suggestion seems ok, just add a hard coded string instead of
the NULL. And keep the coresight_get_uci_data() the same.