Re: [PATCH v4 10/12] thermal: armada: Wait sensors validity before exiting the init callback

From: Gregory CLEMENT <gregory.clement@free-electrons.com>
To: Miquel Raynal <miquel.raynal@free-electrons.com>
Cc: Mark Rutland <mark.rutland@arm.com>, Andrew Lunn <andrew@lunn.ch>,
	Baruch Siach <baruch@tkos.co.il>,
	Jason Cooper <jason@lakedaemon.net>,
	Nadav Haklai <nadavh@marvell.com>,
	linux-pm@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Antoine Tenart <antoine.tenart@free-electrons.com>,
	Will Deacon <will.deacon@arm.com>,
	David Sniatkiwicz <davidsn@marvell.com>,
	Eduardo Valentin <edubezval@gmail.com>,
	devicetree@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
	Zhang Rui <rui.zhang@intel.com>,
	Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
	linux-arm-kernel@lists.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Subject: Re: [PATCH v4 10/12] thermal: armada: Wait sensors validity before exiting the init callback
Date: Mon, 18 Dec 2017 17:12:08 +0100	[thread overview]
Message-ID: <87h8sohv6v.fsf@free-electrons.com> (raw)
In-Reply-To: <20171218143643.7714-11-miquel.raynal@free-electrons.com> (Miquel Raynal's message of "Mon, 18 Dec 2017 15:36:41 +0100")

Hi Miquel,

 On lun., déc. 18 2017, Miquel Raynal <miquel.raynal@free-electrons.com> wrote:

> The thermal core will check for sensors validity right after the
> initialization callback has returned. As the initialization routine make
> a reset, the sensors are not ready immediately and the core spawns an
> error in the dmesg. Avoid this annoying situation by polling on the
> validity bit before exiting from these routines. This also avoid the use
> of blind sleeps.
>
> Suggested-by: David Sniatkiwicz <davidsn@marvell.com>
> Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>

Reviewed-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

> ---
>  drivers/thermal/armada_thermal.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/thermal/armada_thermal.c b/drivers/thermal/armada_thermal.c
> index 2eadd662591d..4a5164ddffe7 100644
> --- a/drivers/thermal/armada_thermal.c
> +++ b/drivers/thermal/armada_thermal.c
> @@ -23,6 +23,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/of_device.h>
>  #include <linux/thermal.h>
> +#include <linux/iopoll.h>
>  
>  /* Thermal Manager Control and Status Register */
>  #define PMU_TDC0_SW_RST_MASK		(0x1 << 1)
> @@ -59,6 +60,9 @@
>  #define CONTROL1_EXT_TSEN_SW_RESET	BIT(7)
>  #define CONTROL1_EXT_TSEN_HW_RESETn	BIT(8)
>  
> +#define STATUS_POLL_PERIOD_US		1000
> +#define STATUS_POLL_TIMEOUT_US		100000
> +
>  struct armada_thermal_data;
>  
>  /* Marvell EBU Thermal Sensor Dev Structure */
> @@ -155,6 +159,16 @@ static void armada375_init_sensor(struct platform_device *pdev,
>  	msleep(50);
>  }
>  
> +static void armada_wait_sensor_validity(struct armada_thermal_priv *priv)
> +{
> +	u32 reg;
> +
> +	readl_relaxed_poll_timeout(priv->status, reg,
> +				   reg & priv->data->is_valid_bit,
> +				   STATUS_POLL_PERIOD_US,
> +				   STATUS_POLL_TIMEOUT_US);
> +}
> +
>  static void armada380_init_sensor(struct platform_device *pdev,
>  				  struct armada_thermal_priv *priv)
>  {
> @@ -164,7 +178,6 @@ static void armada380_init_sensor(struct platform_device *pdev,
>  	reg |= CONTROL1_EXT_TSEN_HW_RESETn;
>  	reg &= ~CONTROL1_EXT_TSEN_SW_RESET;
>  	writel(reg, priv->control1);
> -	msleep(10);
>  
>  	/* Set Tsen Tc Trim to correct default value (errata #132698) */
>  	if (priv->control0) {
> @@ -172,8 +185,10 @@ static void armada380_init_sensor(struct platform_device *pdev,
>  		reg &= ~CONTROL0_TSEN_TC_TRIM_MASK;
>  		reg |= CONTROL0_TSEN_TC_TRIM_VAL;
>  		writel(reg, priv->control0);
> -		msleep(10);
>  	}
> +
> +	/* Wait the sensors to be valid or the core will warn the user */
> +	armada_wait_sensor_validity(priv);
>  }
>  
>  static void armada_ap806_init_sensor(struct platform_device *pdev,
> @@ -185,7 +200,9 @@ static void armada_ap806_init_sensor(struct platform_device *pdev,
>  	reg &= ~CONTROL0_TSEN_RESET;
>  	reg |= CONTROL0_TSEN_START | CONTROL0_TSEN_ENABLE;
>  	writel(reg, priv->control0);
> -	msleep(10);
> +
> +	/* Wait the sensors to be valid or the core will warn the user

Just out of curiosity but how the core will warn the user?

Gregory

> */
> +	armada_wait_sensor_validity(priv);
>  }
>  
>  static bool armada_is_valid(struct armada_thermal_priv *priv)
> -- 
> 2.11.0
>

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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