Re: [PATCH V2 5/7] coresight: tmc: Move ACPI support from AMBA driver to platform driver

James Clark
2023-12-04T10:54:21Z

On 01/12/2023 06:20, Anshuman Khandual wrote:
> Add support for the tmc 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.
>
[...]
> -module_amba_driver(tmc_driver);
> +static int tmc_platform_probe(struct platform_device *pdev)
> +{
> + struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + struct tmc_drvdata *drvdata;
> + int ret = 0;
> +
> + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
> + if (!drvdata)
> + return -ENOMEM;
> +
> + drvdata->pclk = coresight_get_enable_apb_pclk(&pdev->dev);
> + if (IS_ERR(drvdata->pclk))
> + return -ENODEV;
> +
> + dev_set_drvdata(&pdev->dev, drvdata);
> + pm_runtime_get_noresume(&pdev->dev);
> + pm_runtime_set_active(&pdev->dev);
> + pm_runtime_enable(&pdev->dev);
> +
> + ret = __tmc_probe(&pdev->dev, res, NULL);
> + if (ret) {
> + pm_runtime_put_noidle(&pdev->dev);
> + pm_runtime_disable(&pdev->dev);
> + }

I'm not sure if these pm_runtime()s are right because there is already a
put inside of __tmc_probe() if it fails. If you unload and then reload
all the coresight modules with these patches you get these errors which
are new:

coresight-tpiu-platform ARMHC979:00: Unbalanced pm_runtime_enable!
CSCFG registered etm0
coresight etm0: CPU0: etm v4.2 initialized
CSCFG registered etm1
coresight etm1: CPU1: etm v4.2 initialized
CSCFG registered etm2
coresight etm2: CPU2: etm v4.2 initialized
CSCFG registered etm3
coresight etm3: CPU3: etm v4.2 initialized
coresight-tmc-platform ARMHC97C:00: Unbalanced pm_runtime_enable!
coresight-tmc-platform ARMHC97C:01: Unbalanced pm_runtime_enable!
coresight-tmc-platform ARMHC97C:02: Unbalanced pm_runtime_enable!
coresight-tmc-platform ARMHC97C:03: Unbalanced pm_runtime_enable!

It might be worth testing all of these pm_runtime()s, including the
error case ones, because loading and unloading the modules doesn't even
include the error scenarios, so there are probably more bad ones in
there too.