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

[Suzuki K Poulose]

On 05/12/2023 05:20, Anshuman Khandual wrote:
> On 12/4/23 18:47, James Clark wrote:
> > 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@xxxxxxxxxx>
> > > > > Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
> > > > > Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > > > > Cc: Mike Leach <mike.leach@xxxxxxxxxx>
> > > > > Cc: James Clark <james.clark@xxxxxxx>
> > > > > Cc: Maxime Coquelin <mcoquelin.stm32@xxxxxxxxx>
> > > > > Cc: Alexandre Torgue <alexandre.torgue@xxxxxxxxxxx>
> > > > > Cc: linux-acpi@xxxxxxxxxxxxxxx
> > > > > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > > > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > > > Cc: coresight@xxxxxxxxxxxxxxxx
> > > > > Cc: linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > > > > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> > > > > ---
> > > > [...]
> > > > >   
> > > > > -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.
>
> Something like this works ?
>
> diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
> index 3387ebc9d8ab..2b6834c4cac6 100644
> --- a/drivers/hwtracing/coresight/coresight-stm.c
> +++ b/drivers/hwtracing/coresight/coresight-stm.c
> @@ -906,7 +906,7 @@ static int __stm_probe(struct device *dev, struct resource *res, void *dev_caps)
>          pm_runtime_put(dev);
>   
>          dev_info(&drvdata->csdev->dev, "%s initialized\n",
> -                (char *)dev_caps);
> +                dev_caps ? (char *)dev_caps: "STM");
>          return 0;
>   

Please could stop abusing the private data for storing the name ? 
Instead, we could read the PID of the device and use a table to map
it to the name and use that instead ?

Suzuki


>   cs_unregister: