Re: [PATCH V3 04/10] coresight: replicator: Move ACPI support from AMBA driver to platform driver

[Anshuman Khandual <anshuman.khandual@arm.com>]

On 12/8/23 11:09, Anshuman Khandual wrote:
> Add support for the dynamic replicator device in the platform driver, which
> can then be used on ACPI based platforms. This change would now allow
> runtime power management for repliacator devices on ACPI based systems.
> 
> The driver would try to enable the APB clock if available. Also, rename the
> code to reflect the fact that it now handles both static and dynamic
> replicators.
> 
> Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> Cc: Mike Leach <mike.leach@linaro.org>
> Cc: James Clark <james.clark@arm.com>
> Cc: linux-acpi@vger.kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Cc: coresight@lists.linaro.org
> Tested-by: Sudeep Holla <sudeep.holla@arm.com> # Boot and driver probe only
> Acked-by: Sudeep Holla <sudeep.holla@arm.com> # For ACPI related changes
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> Changes in V3:
> 
> - Added commnets for 'drvdata->pclk'
> - Used coresight_init_driver()/coresight_remove_driver() helpers instead
> - Dropped pm_runtime_put() from replicator_probe()
> - Added pm_runtime_put() on success path in dynamic_replicator_probe()
> - Added pm_runtime_put() on success/error paths in
>   replicator_platform_probe()
> 
>  drivers/acpi/arm64/amba.c                     |  1 -
>  .../coresight/coresight-replicator.c          | 81 ++++++++++---------
>  2 files changed, 42 insertions(+), 40 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/amba.c b/drivers/acpi/arm64/amba.c
> index 171b5c2c7edd..270f4e3819a2 100644
> --- a/drivers/acpi/arm64/amba.c
> +++ b/drivers/acpi/arm64/amba.c
> @@ -27,7 +27,6 @@ static const struct acpi_device_id amba_id_list[] = {
>  	{"ARMHC503", 0}, /* ARM CoreSight Debug */
>  	{"ARMHC979", 0}, /* ARM CoreSight TPIU */
>  	{"ARMHC97C", 0}, /* ARM CoreSight SoC-400 TMC, SoC-600 ETF/ETB */
> -	{"ARMHC98D", 0}, /* ARM CoreSight Dynamic Replicator */
>  	{"ARMHC9CA", 0}, /* ARM CoreSight CATU */
>  	{"ARMHC9FF", 0}, /* ARM CoreSight Dynamic Funnel */
>  	{"", 0},
> diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
> index b6be73034996..125b256cb8db 100644
> --- a/drivers/hwtracing/coresight/coresight-replicator.c
> +++ b/drivers/hwtracing/coresight/coresight-replicator.c
> @@ -31,6 +31,7 @@ DEFINE_CORESIGHT_DEVLIST(replicator_devs, "replicator");
>   * @base:	memory mapped base address for this component. Also indicates
>   *		whether this one is programmable or not.
>   * @atclk:	optional clock for the core parts of the replicator.
> + * @pclk:	APB clock if present, otherwise NULL
>   * @csdev:	component vitals needed by the framework
>   * @spinlock:	serialize enable/disable operations.
>   * @check_idfilter_val: check if the context is lost upon clock removal.
> @@ -38,6 +39,7 @@ DEFINE_CORESIGHT_DEVLIST(replicator_devs, "replicator");
>  struct replicator_drvdata {
>  	void __iomem		*base;
>  	struct clk		*atclk;
> +	struct clk		*pclk;
>  	struct coresight_device	*csdev;
>  	spinlock_t		spinlock;
>  	bool			check_idfilter_val;
> @@ -243,6 +245,10 @@ static int replicator_probe(struct device *dev, struct resource *res)
>  			return ret;
>  	}
>  
> +	drvdata->pclk = coresight_get_enable_apb_pclk(dev);
> +	if (IS_ERR(drvdata->pclk))
> +		return -ENODEV;
> +
>  	/*
>  	 * Map the device base for dynamic-replicator, which has been
>  	 * validated by AMBA core
> @@ -285,7 +291,6 @@ static int replicator_probe(struct device *dev, struct resource *res)
>  	}
>  
>  	replicator_reset(drvdata);
> -	pm_runtime_put(dev);
>  
>  out_disable_clk:
>  	if (ret && !IS_ERR_OR_NULL(drvdata->atclk))
> @@ -301,29 +306,31 @@ static int replicator_remove(struct device *dev)
>  	return 0;
>  }
>  
> -static int static_replicator_probe(struct platform_device *pdev)
> +static int replicator_platform_probe(struct platform_device *pdev)
>  {
> +	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	int ret;
>  
>  	pm_runtime_get_noresume(&pdev->dev);
>  	pm_runtime_set_active(&pdev->dev);
>  	pm_runtime_enable(&pdev->dev);
>  
> -	/* Static replicators do not have programming base */
> -	ret = replicator_probe(&pdev->dev, NULL);
> -
> -	if (ret) {
> -		pm_runtime_put_noidle(&pdev->dev);
> -		pm_runtime_disable(&pdev->dev);
> -	}
> +	ret = replicator_probe(&pdev->dev, res);
> +	pm_runtime_put(&pdev->dev);

I believe pm_runtime_disable() would still be needed on the error path. Otherwise
pm_runtime_enable() will remain unbalanced on this error path when the replicator
module could not be loaded.

--- a/drivers/hwtracing/coresight/coresight-replicator.c
+++ b/drivers/hwtracing/coresight/coresight-replicator.c
@@ -317,6 +317,8 @@ static int replicator_platform_probe(struct platform_device *pdev)
 
        ret = replicator_probe(&pdev->dev, res);
        pm_runtime_put(&pdev->dev);
+       if (ret)
+               pm_runtime_disable(&pdev->dev);
 
        return ret;
 }

Similar constructs in this error path are also required in all other drivers (except
cpu debug) as well.