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Message-ID: <0ebbc509-9e17-4b93-9a72-b9e7cc03637e@arm.com>
Date: Fri, 2 May 2025 14:15:49 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Leo Yan <leo.yan@....com>, Suzuki K Poulose <suzuki.poulose@....com>,
Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>, coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH v2 9/9] coresight: Refactor runtime PM
On 4/23/25 20:47, Leo Yan wrote:
> The validation for driver data pointers and clock pointers are redundant
> in the runtime PM callbacks. After a driver's probing, its driver data
> and clocks have been initialized successfully, this ensures it is safe
> to access driver data and clocks in the runtime PM callbacks. A corner
> case is a clock pointer is NULL, in this case, the clock core layer can
> handle it properly. So remove these redundant checking.
>
> In runtime resume, respect values returned from clock function and add
> error handling.
Although not checking drvdata and drvdata->apb_clk does make sense, but
why change the semantics on the resume paths as well, which now returns
stored error value from clk_prepare_enable().
>
> Signed-off-by: Leo Yan <leo.yan@....com>
> ---
> drivers/hwtracing/coresight/coresight-cpu-debug.c | 8 +++-----
> drivers/hwtracing/coresight/coresight-ctcu-core.c | 8 ++------
> drivers/hwtracing/coresight/coresight-etb10.c | 8 ++------
> drivers/hwtracing/coresight/coresight-etm3x-core.c | 8 ++------
> drivers/hwtracing/coresight/coresight-funnel.c | 21 +++++++++++----------
> drivers/hwtracing/coresight/coresight-replicator.c | 20 +++++++++++---------
> drivers/hwtracing/coresight/coresight-stm.c | 20 +++++++++++---------
> drivers/hwtracing/coresight/coresight-tpiu.c | 20 +++++++++++---------
> 8 files changed, 53 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> index 481ffcbed534..dff663ac7805 100644
> --- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
> +++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> @@ -731,8 +731,8 @@ static int debug_runtime_suspend(struct device *dev)
> {
> struct debug_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_disable_unprepare(drvdata->pclk);
> + clk_disable_unprepare(drvdata->pclk);
> +
> return 0;
> }
>
> @@ -740,9 +740,7 @@ static int debug_runtime_resume(struct device *dev)
> {
> struct debug_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_prepare_enable(drvdata->pclk);
> - return 0;
> + return clk_prepare_enable(drvdata->pclk);
> }
> #endif
>
> diff --git a/drivers/hwtracing/coresight/coresight-ctcu-core.c b/drivers/hwtracing/coresight/coresight-ctcu-core.c
> index 75b5114ef652..c586495e9a08 100644
> --- a/drivers/hwtracing/coresight/coresight-ctcu-core.c
> +++ b/drivers/hwtracing/coresight/coresight-ctcu-core.c
> @@ -278,8 +278,7 @@ static int ctcu_runtime_suspend(struct device *dev)
> {
> struct ctcu_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->apb_clk))
> - clk_disable_unprepare(drvdata->apb_clk);
> + clk_disable_unprepare(drvdata->apb_clk);
>
> return 0;
> }
> @@ -288,10 +287,7 @@ static int ctcu_runtime_resume(struct device *dev)
> {
> struct ctcu_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->apb_clk))
> - clk_prepare_enable(drvdata->apb_clk);
> -
> - return 0;
> + return clk_prepare_enable(drvdata->apb_clk);
> }
> #endif
>
> diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
> index 45c2f8f50a3f..3f3b0eb48fdb 100644
> --- a/drivers/hwtracing/coresight/coresight-etb10.c
> +++ b/drivers/hwtracing/coresight/coresight-etb10.c
> @@ -807,8 +807,7 @@ static int etb_runtime_suspend(struct device *dev)
> {
> struct etb_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->atclk);
>
> return 0;
> }
> @@ -817,10 +816,7 @@ static int etb_runtime_resume(struct device *dev)
> {
> struct etb_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_prepare_enable(drvdata->atclk);
> -
> - return 0;
> + return clk_prepare_enable(drvdata->atclk);
> }
> #endif
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> index adbb134f80e6..615ff743eef0 100644
> --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
> +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> @@ -925,8 +925,7 @@ static int etm_runtime_suspend(struct device *dev)
> {
> struct etm_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->atclk);
>
> return 0;
> }
> @@ -935,10 +934,7 @@ static int etm_runtime_resume(struct device *dev)
> {
> struct etm_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_prepare_enable(drvdata->atclk);
> -
> - return 0;
> + return clk_prepare_enable(drvdata->atclk);
> }
> #endif
>
> diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c
> index 62e5125c37ad..6494a3b5d18e 100644
> --- a/drivers/hwtracing/coresight/coresight-funnel.c
> +++ b/drivers/hwtracing/coresight/coresight-funnel.c
> @@ -283,11 +283,8 @@ static int funnel_runtime_suspend(struct device *dev)
> {
> struct funnel_drvdata *drvdata = dev_get_drvdata(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);
> + clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->pclk);
>
> return 0;
> }
> @@ -295,13 +292,17 @@ static int funnel_runtime_suspend(struct device *dev)
> static int funnel_runtime_resume(struct device *dev)
> {
> struct funnel_drvdata *drvdata = dev_get_drvdata(dev);
> + int ret;
> +
> + ret = clk_prepare_enable(drvdata->pclk);
> + if (ret)
> + return ret;
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_prepare_enable(drvdata->pclk);
> + ret = clk_prepare_enable(drvdata->atclk);
> + if (ret)
> + clk_disable_unprepare(drvdata->pclk);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_prepare_enable(drvdata->atclk);
> - return 0;
> + return ret;
> }
> #endif
>
> diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
> index 56b03e6d8336..8595dc104795 100644
> --- a/drivers/hwtracing/coresight/coresight-replicator.c
> +++ b/drivers/hwtracing/coresight/coresight-replicator.c
> @@ -322,24 +322,26 @@ static int replicator_runtime_suspend(struct device *dev)
> {
> struct replicator_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->pclk);
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_disable_unprepare(drvdata->pclk);
> return 0;
> }
>
> static int replicator_runtime_resume(struct device *dev)
> {
> struct replicator_drvdata *drvdata = dev_get_drvdata(dev);
> + int ret;
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_prepare_enable(drvdata->pclk);
> + ret = clk_prepare_enable(drvdata->pclk);
> + if (ret)
> + return ret;
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_prepare_enable(drvdata->atclk);
> - return 0;
> + ret = clk_prepare_enable(drvdata->atclk);
> + if (ret)
> + clk_disable_unprepare(drvdata->pclk);
> +
> + return ret;
> }
> #endif
>
> diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
> index f17986edac00..f859ab932d22 100644
> --- a/drivers/hwtracing/coresight/coresight-stm.c
> +++ b/drivers/hwtracing/coresight/coresight-stm.c
> @@ -957,24 +957,26 @@ static int stm_runtime_suspend(struct device *dev)
> {
> struct stm_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->pclk);
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_disable_unprepare(drvdata->pclk);
> return 0;
> }
>
> static int stm_runtime_resume(struct device *dev)
> {
> struct stm_drvdata *drvdata = dev_get_drvdata(dev);
> + int ret;
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_prepare_enable(drvdata->pclk);
> + ret = clk_prepare_enable(drvdata->pclk);
> + if (ret)
> + return ret;
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_prepare_enable(drvdata->atclk);
> - return 0;
> + ret = clk_prepare_enable(drvdata->atclk);
> + if (ret)
> + clk_disable_unprepare(drvdata->pclk);
> +
> + return ret;
> }
> #endif
>
> diff --git a/drivers/hwtracing/coresight/coresight-tpiu.c b/drivers/hwtracing/coresight/coresight-tpiu.c
> index 4701b34778bd..a68ed6b97bf7 100644
> --- a/drivers/hwtracing/coresight/coresight-tpiu.c
> +++ b/drivers/hwtracing/coresight/coresight-tpiu.c
> @@ -206,24 +206,26 @@ static int tpiu_runtime_suspend(struct device *dev)
> {
> struct tpiu_drvdata *drvdata = dev_get_drvdata(dev);
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->atclk);
> + clk_disable_unprepare(drvdata->pclk);
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_disable_unprepare(drvdata->pclk);
> return 0;
> }
>
> static int tpiu_runtime_resume(struct device *dev)
> {
> struct tpiu_drvdata *drvdata = dev_get_drvdata(dev);
> + int ret;
>
> - if (drvdata && !IS_ERR_OR_NULL(drvdata->pclk))
> - clk_prepare_enable(drvdata->pclk);
> + ret = clk_prepare_enable(drvdata->pclk);
> + if (ret)
> + return ret;
>
> - if (drvdata && !IS_ERR(drvdata->atclk))
> - clk_prepare_enable(drvdata->atclk);
> - return 0;
> + ret = clk_prepare_enable(drvdata->atclk);
> + if (ret)
> + clk_disable_unprepare(drvdata->pclk);
> +
> + return ret;
> }
> #endif
>
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