linux-kernel - Re: [PATCH v1 7/9] coresight: Make clock sequence consistent

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Message-ID: <d94c6f97-4ca8-4a3a-ae8a-8e872eaa8d3b@arm.com>
Date: Thu, 3 Apr 2025 12:40:39 +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 v1 7/9] coresight: Make clock sequence consistent

On 3/27/25 17:08, Leo Yan wrote:
> Since atclk is enabled after pclk during the probe phase, this commit
> maintains the same sequence for the runtime resume flow.
> 
> Signed-off-by: Leo Yan <leo.yan@....com>
> ---
>  drivers/hwtracing/coresight/coresight-funnel.c     | 6 +++---
>  drivers/hwtracing/coresight/coresight-replicator.c | 6 +++---
>  drivers/hwtracing/coresight/coresight-stm.c        | 6 +++---
>  drivers/hwtracing/coresight/coresight-tpiu.c       | 6 +++---
>  4 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-funnel.c b/drivers/hwtracing/coresight/coresight-funnel.c
> index ec6d3e656548..e378c2fffca9 100644
> --- a/drivers/hwtracing/coresight/coresight-funnel.c
> +++ b/drivers/hwtracing/coresight/coresight-funnel.c
> @@ -299,11 +299,11 @@ static int funnel_runtime_resume(struct device *dev)
>  {
>  	struct funnel_drvdata *drvdata = dev_get_drvdata(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);
> +
> +	if (drvdata && !IS_ERR(drvdata->atclk))
> +		clk_prepare_enable(drvdata->atclk);
>  	return 0;
>  }

funnel_probe() enables pclk after atclk though - which needs to be
reversed as well ?

static int funnel_probe(struct device *dev, struct resource *res)
{
	..................
        drvdata->atclk = devm_clk_get_optional_enabled(dev, "atclk");
        if (IS_ERR(drvdata->atclk))
                return PTR_ERR(drvdata->atclk);

        drvdata->pclk = coresight_get_enable_apb_pclk(dev);
        if (IS_ERR(drvdata->pclk))
                return PTR_ERR(drvdata->pclk);

>  #endif
> diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
> index 460af0f7b537..78854f586e89 100644
> --- a/drivers/hwtracing/coresight/coresight-replicator.c
> +++ b/drivers/hwtracing/coresight/coresight-replicator.c
> @@ -337,11 +337,11 @@ static int replicator_runtime_resume(struct device *dev)
>  {
>  	struct replicator_drvdata *drvdata = dev_get_drvdata(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);
> +
> +	if (drvdata && !IS_ERR(drvdata->atclk))
> +		clk_prepare_enable(drvdata->atclk);
>  	return 0;
>  }

replicator_probe() enables pclk after atclk though - which needs to be
reversed as well ?

static int replicator_probe(struct device *dev, struct resource *res)
{
	..................
        drvdata->atclk = devm_clk_get_optional_enabled(dev, "atclk");
        if (IS_ERR(drvdata->atclk))
                return PTR_ERR(drvdata->atclk);

        drvdata->pclk = coresight_get_enable_apb_pclk(dev);
        if (IS_ERR(drvdata->pclk))
                return PTR_ERR(drvdata->pclk);



>  #endif
> diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
> index f13fbab4d7a2..ddb4f6678efd 100644
> --- a/drivers/hwtracing/coresight/coresight-stm.c
> +++ b/drivers/hwtracing/coresight/coresight-stm.c
> @@ -972,11 +972,11 @@ static int stm_runtime_resume(struct device *dev)
>  {
>  	struct stm_drvdata *drvdata = dev_get_drvdata(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);
> +
> +	if (drvdata && !IS_ERR(drvdata->atclk))
> +		clk_prepare_enable(drvdata->atclk);
>  	return 0;
>  }
>  #endif

same here as well.

> diff --git a/drivers/hwtracing/coresight/coresight-tpiu.c b/drivers/hwtracing/coresight/coresight-tpiu.c
> index cac1b5bba086..8212959f60d4 100644
> --- a/drivers/hwtracing/coresight/coresight-tpiu.c
> +++ b/drivers/hwtracing/coresight/coresight-tpiu.c
> @@ -220,11 +220,11 @@ static int tpiu_runtime_resume(struct device *dev)
>  {
>  	struct tpiu_drvdata *drvdata = dev_get_drvdata(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);
> +
> +	if (drvdata && !IS_ERR(drvdata->atclk))
> +		clk_prepare_enable(drvdata->atclk);
>  	return 0;
>  }
>  #endif

same here as well.

I assume this patch is trying to have the same clock sequence enablement
during original probe and resume path and then just the reverse sequence
during suspend path.