linux-kernel - Re: [PATCH v4 1/2] thermal: rcar_gen3

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Message-ID: <1bdc45cd-12fb-e607-1ab5-f06a022b263e@linaro.org>
Date:   Wed, 24 Apr 2019 11:31:45 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Jiada Wang <jiada_wang@...tor.com>, rui.zhang@...el.com,
        edubezval@...il.com
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        horms+renesas@...ge.net.au, niklas.soderlund+renesas@...natech.se,
        geert+renesas@...der.be, sergei.shtylyov@...entembedded.com,
        marek.vasut+renesas@...il.com, kuninori.morimoto.gx@...esas.com,
        hien.dang.eb@...esas.com, fabrizio.castro@...renesas.com,
        dien.pham.ry@...esas.com, biju.das@...renesas.com,
        erosca@...adit-jv.com, george_davis@...tor.com,
        joshua_frkuska@...tor.com
Subject: Re: [PATCH v4 1/2] thermal: rcar_gen3_thermal: fix interrupt type

On 24/04/2019 07:11, Jiada Wang wrote:
> Currently IRQF_SHARED type interrupt line is allocated, but it
> is not appropriate, as the interrupt line isn't shared between
> different devices, instead IRQF_ONESHOT is the proper type.
> 
> By changing interrupt type to IRQF_ONESHOT, now irq handler is
> no longer needed, as clear of interrupt status can be done in
> threaded interrupt context.
> 
> Because IRQF_ONESHOT type interrupt line is kept disabled until
> the threaded handler has been run, so there is no need to protect
> read/write of REG_GEN3_IRQSTR with lock.
> 
> Fixes: 7d4b269776ec6 ("enable hardware interrupts for trip points")
> Signed-off-by: Jiada Wang <jiada_wang@...tor.com>

Suggested-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Reviewed-by: Daniel Lezcano <daniel.lezcano@...aro.org>

> ---
>  drivers/thermal/rcar_gen3_thermal.c | 38 +++++------------------------
>  1 file changed, 6 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/thermal/rcar_gen3_thermal.c b/drivers/thermal/rcar_gen3_thermal.c
> index 88fa41cf16e8..065e16f53285 100644
> --- a/drivers/thermal/rcar_gen3_thermal.c
> +++ b/drivers/thermal/rcar_gen3_thermal.c
> @@ -14,7 +14,6 @@
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> -#include <linux/spinlock.h>
>  #include <linux/sys_soc.h>
>  #include <linux/thermal.h>
>  
> @@ -82,7 +81,6 @@ struct rcar_gen3_thermal_tsc {
>  struct rcar_gen3_thermal_priv {
>  	struct rcar_gen3_thermal_tsc *tscs[TSC_MAX_NUM];
>  	unsigned int num_tscs;
> -	spinlock_t lock; /* Protect interrupts on and off */
>  	void (*thermal_init)(struct rcar_gen3_thermal_tsc *tsc);
>  };
>  
> @@ -232,38 +230,16 @@ static irqreturn_t rcar_gen3_thermal_irq(int irq, void *data)
>  {
>  	struct rcar_gen3_thermal_priv *priv = data;
>  	u32 status;
> -	int i, ret = IRQ_HANDLED;
> +	int i;
>  
> -	spin_lock(&priv->lock);
>  	for (i = 0; i < priv->num_tscs; i++) {
>  		status = rcar_gen3_thermal_read(priv->tscs[i], REG_GEN3_IRQSTR);
>  		rcar_gen3_thermal_write(priv->tscs[i], REG_GEN3_IRQSTR, 0);
>  		if (status)
> -			ret = IRQ_WAKE_THREAD;
> +			thermal_zone_device_update(priv->tscs[i]->zone,
> +						   THERMAL_EVENT_UNSPECIFIED);
>  	}
>  
> -	if (ret == IRQ_WAKE_THREAD)
> -		rcar_thermal_irq_set(priv, false);
> -
> -	spin_unlock(&priv->lock);
> -
> -	return ret;
> -}
> -
> -static irqreturn_t rcar_gen3_thermal_irq_thread(int irq, void *data)
> -{
> -	struct rcar_gen3_thermal_priv *priv = data;
> -	unsigned long flags;
> -	int i;
> -
> -	for (i = 0; i < priv->num_tscs; i++)
> -		thermal_zone_device_update(priv->tscs[i]->zone,
> -					   THERMAL_EVENT_UNSPECIFIED);
> -
> -	spin_lock_irqsave(&priv->lock, flags);
> -	rcar_thermal_irq_set(priv, true);
> -	spin_unlock_irqrestore(&priv->lock, flags);
> -
>  	return IRQ_HANDLED;
>  }
>  
> @@ -371,8 +347,6 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
>  	if (soc_device_match(r8a7795es1))
>  		priv->thermal_init = rcar_gen3_thermal_init_r8a7795es1;
>  
> -	spin_lock_init(&priv->lock);
> -
>  	platform_set_drvdata(pdev, priv);
>  
>  	/*
> @@ -390,9 +364,9 @@ static int rcar_gen3_thermal_probe(struct platform_device *pdev)
>  		if (!irqname)
>  			return -ENOMEM;
>  
> -		ret = devm_request_threaded_irq(dev, irq, rcar_gen3_thermal_irq,
> -						rcar_gen3_thermal_irq_thread,
> -						IRQF_SHARED, irqname, priv);
> +		ret = devm_request_threaded_irq(dev, irq, NULL,
> +						rcar_gen3_thermal_irq,
> +						IRQF_ONESHOT, irqname, priv);
>  		if (ret)
>  			return ret;
>  	}
> 


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