Re: [PATCH V6 06/11] coresight: funnel: Move ACPI support from AMBA driver to platform driver

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

On 3/12/24 20:11, Suzuki K Poulose wrote:
> On 12/03/2024 10:23, Anshuman Khandual wrote:
>> Add support for the dynamic funnel device in the platform driver, which can
>> then be used on ACPI based platforms. This change would allow runtime power
>> management for 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
>> funnels. But first this refactors funnel_probe() making sure it can be used
>> both for platform and AMBA drivers, by moving the pm_runtime_put() to the
>> callers.
>>
>> 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
>> Reviewed-by: James Clark <james.clark@arm.com>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> Changes in V6:
>>
>> - Added clk_disable_unprepare() for pclk in funnel_probe() error path
>> - Added WARN_ON(!drvdata) check in funnel_platform_remove()
>> - Added additional elements for acpi_device_id[]
>>
>>   drivers/acpi/arm64/amba.c                     |  1 -
>>   .../hwtracing/coresight/coresight-funnel.c    | 72 ++++++++++++-------
>>   2 files changed, 48 insertions(+), 25 deletions(-)
>>
>> diff --git a/drivers/acpi/arm64/amba.c b/drivers/acpi/arm64/amba.c
>> index 270f4e3819a2..afb6afb66967 100644
>> --- a/drivers/acpi/arm64/amba.c
>> +++ b/drivers/acpi/arm64/amba.c
>> @@ -28,7 +28,6 @@ static const struct acpi_device_id amba_id_list[] = {
>>       {"ARMHC979", 0}, /* ARM CoreSight TPIU */
>>       {"ARMHC97C", 0}, /* ARM CoreSight SoC-400 TMC, SoC-600 ETF/ETB */
>>       {"ARMHC9CA", 0}, /* ARM CoreSight CATU */
>> -    {"ARMHC9FF", 0}, /* ARM CoreSight Dynamic Funnel */
>>       {"", 0},
>>   };
>>   diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c
>> index ff3ea0670a5b..3b4be10a0f0c 100644
>> --- a/drivers/hwtracing/coresight/coresight-funnel.c
>> +++ b/drivers/hwtracing/coresight/coresight-funnel.c
>> @@ -36,6 +36,7 @@ DEFINE_CORESIGHT_DEVLIST(funnel_devs, "funnel");
>>    * struct funnel_drvdata - specifics associated to a funnel component
>>    * @base:    memory mapped base address for this component.
>>    * @atclk:    optional clock for the core parts of the funnel.
>> + * @pclk:    APB clock if present, otherwise NULL
>>    * @csdev:    component vitals needed by the framework.
>>    * @priority:    port selection order.
>>    * @spinlock:    serialize enable/disable operations.
>> @@ -43,6 +44,7 @@ DEFINE_CORESIGHT_DEVLIST(funnel_devs, "funnel");
>>   struct funnel_drvdata {
>>       void __iomem        *base;
>>       struct clk        *atclk;
>> +    struct clk        *pclk;
>>       struct coresight_device    *csdev;
>>       unsigned long        priority;
>>       spinlock_t        spinlock;
>> @@ -236,6 +238,10 @@ static int funnel_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-funnel, which has been
>>        * validated by AMBA core.
>> @@ -272,12 +278,13 @@ static int funnel_probe(struct device *dev, struct resource *res)
>>           goto out_disable_clk;
>>       }
>>   -    pm_runtime_put(dev);
>>       ret = 0;
>>     out_disable_clk:
>>       if (ret && !IS_ERR_OR_NULL(drvdata->atclk))
>>           clk_disable_unprepare(drvdata->atclk);
>> +    if (ret && !IS_ERR_OR_NULL(drvdata->pclk))
>> +        clk_disable_unprepare(drvdata->pclk);
>>       return ret;
>>   }
>>   @@ -298,6 +305,9 @@ static int funnel_runtime_suspend(struct device *dev)
>>       if (drvdata && !IS_ERR(drvdata->atclk))
>>           clk_disable_unprepare(drvdata->atclk);
>>   +    if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
>> +        clk_disable_unprepare(drvdata->pclk);
>> +
>>       return 0;
>>   }
>>   @@ -308,6 +318,8 @@ static int funnel_runtime_resume(struct device *dev)
>>       if (drvdata && !IS_ERR(drvdata->atclk))
>>           clk_prepare_enable(drvdata->atclk);
>>   +    if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
>> +        clk_prepare_enable(drvdata->pclk);
>>       return 0;
>>   }
>>   #endif
>> @@ -316,55 +328,61 @@ static const struct dev_pm_ops funnel_dev_pm_ops = {
>>       SET_RUNTIME_PM_OPS(funnel_runtime_suspend, funnel_runtime_resume, NULL)
>>   };
>>   -static int static_funnel_probe(struct platform_device *pdev)
>> +static int funnel_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 funnel do not have programming base */
>> -    ret = funnel_probe(&pdev->dev, NULL);
>> -
>> -    if (ret) {
>> -        pm_runtime_put_noidle(&pdev->dev);
>> +    ret = funnel_probe(&pdev->dev, res);
>> +    pm_runtime_put(&pdev->dev);
>> +    if (ret)
>>           pm_runtime_disable(&pdev->dev);
>> -    }
>>         return ret;
>>   }
>>   -static void static_funnel_remove(struct platform_device *pdev)
>> +static void funnel_platform_remove(struct platform_device *pdev)
>>   {
>> +    struct funnel_drvdata *drvdata = dev_get_drvdata(&pdev->dev);
>> +
>> +    if (WARN_ON(!drvdata))
>> +        return;
>> +
>>       funnel_remove(&pdev->dev);
>>       pm_runtime_disable(&pdev->dev);
>> +    if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> 
> Same as the previous patch

Right, unlike in xxx_runtime_suspend/resume() functions, xxx_platform_remove()
functions do have a (!drvdata) check right at the beginning. Hence a redundant
check in such places can be dropped.