linux-kernel - Re: [PATCH v3 11/13] thermal: qoriq: Do not report invalid temperature reading

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Date:   Thu, 4 Apr 2019 11:05:51 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Andrey Smirnov <andrew.smirnov@...il.com>, linux-pm@...r.kernel.org
Cc:     Chris Healy <cphealy@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Zhang Rui <rui.zhang@...el.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Angus Ainslie <angus@...ea.ca>, linux-imx@....com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 11/13] thermal: qoriq: Do not report invalid
 temperature reading

On 01/04/2019 06:14, Andrey Smirnov wrote:
> Before returning measured temperature data to upper layer we need to
> make sure that the reading was marked as "valid" to avoid reporting
> bogus data.

Is it possible to add a comment above the read_poll to describe the
layout of the register ? That will help to understand the valid bit.

Is the valid bit reset after reading the value?

Other than that, Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>

> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
> Cc: Chris Healy <cphealy@...il.com>
> Cc: Lucas Stach <l.stach@...gutronix.de>
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: Eduardo Valentin <edubezval@...il.com>
> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Angus Ainslie (Purism) <angus@...ea.ca>
> Cc: linux-imx@....com
> Cc: linux-pm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> ---
>  drivers/thermal/qoriq_thermal.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/thermal/qoriq_thermal.c b/drivers/thermal/qoriq_thermal.c
> index 7ff93dfcd68b..9d227654f879 100644
> --- a/drivers/thermal/qoriq_thermal.c
> +++ b/drivers/thermal/qoriq_thermal.c
> @@ -37,6 +37,7 @@
>  #define REGS_TRITSR(n)	(0x100 + 16 * (n)) /* Immediate Temperature
>  					    * Site Register
>  					    */
> +#define TRITSR_V	BIT(31)
>  #define REGS_TTRnCR(n)	(0xf10 + 4 * (n)) /* Temperature Range n
>  					   * Control Register
>  					   */
> @@ -62,10 +63,18 @@ static int tmu_get_temp(void *p, int *temp)
>  	struct qoriq_sensor *qsensor = p;
>  	struct qoriq_tmu_data *qdata = qoriq_sensor_to_data(qsensor);
>  	u32 val;
> +	int ret;
>  
> -	regmap_read(qdata->regmap, REGS_TRITSR(qsensor->id), &val);
> -	*temp = (val & 0xff) * 1000;
> +	ret = regmap_read_poll_timeout(qdata->regmap,
> +				       REGS_TRITSR(qsensor->id),
> +				       val,
> +				       val & TRITSR_V,
> +				       USEC_PER_MSEC,
> +				       10 * USEC_PER_MSEC);
> +	if (ret)
> +		return ret;
>  
> +	*temp = (val & 0xff) * 1000;
>  	return 0;
>  }
>  
> 


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