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From:   Thara Gopinath <thara.gopinath@linaro.org>
Subject: Re: [PATCH v11 5/9] drivers: thermal: tsens: Fix bug in sensor enable
 for msm8960
To:     Ansuel Smith <ansuelsmth@gmail.com>
Cc:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Amit Kucheria <amitk@kernel.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210319005228.1250-1-ansuelsmth@gmail.com>
 <20210319005228.1250-6-ansuelsmth@gmail.com>
Message-ID: <c1771c13-5a9a-ed4e-cf30-9494b165f00b@linaro.org>
Date:   Fri, 19 Mar 2021 09:11:55 -0400
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Hi!

On 3/18/21 8:52 PM, Ansuel Smith wrote:
> Device based on tsens VER_0 contains a hardware bug that results in some
> problem with sensor enablement. Sensor id 6-11 can't be enabled
> selectively and all of them must be enabled in one step.

Thanks for rewording!

> 
> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> ---
>   drivers/thermal/qcom/tsens-8960.c | 24 +++++++++++++++++++++---
>   1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/thermal/qcom/tsens-8960.c b/drivers/thermal/qcom/tsens-8960.c
> index 86585f439985..bdc64d4188bf 100644
> --- a/drivers/thermal/qcom/tsens-8960.c
> +++ b/drivers/thermal/qcom/tsens-8960.c
> @@ -27,9 +27,9 @@
>   #define EN			BIT(0)
>   #define SW_RST			BIT(1)
>   #define SENSOR0_EN		BIT(3)
> +#define MEASURE_PERIOD		BIT(18)
>   #define SLP_CLK_ENA		BIT(26)
>   #define SLP_CLK_ENA_8660	BIT(24)
> -#define MEASURE_PERIOD		1
>   #define SENSOR0_SHIFT		3
>   
>   /* INT_STATUS_ADDR bitmasks */
> @@ -126,17 +126,35 @@ static int resume_8960(struct tsens_priv *priv)
>   static int enable_8960(struct tsens_priv *priv, int id)
>   {
>   	int ret;
> -	u32 reg, mask;
> +	u32 reg, mask = BIT(id);
>   
>   	ret = regmap_read(priv->tm_map, CNTL_ADDR, &reg);
>   	if (ret)
>   		return ret;
>   
> -	mask = BIT(id + SENSOR0_SHIFT);
> +	/* HARDWARE BUG:
> +	 * On platform with more than 6 sensors, all the remaining
> +	 * sensors needs to be enabled all togheder or underfined
> +	 * results are expected. (Sensor 6-7 disabled, Sensor 3
> +	 * disabled...) In the original driver, all the sensors
> +	 * are enabled in one step hence this bug is not triggered.
> +	 */
> +	if (id > 5) {
> +		mask = GENMASK(10, 6);
> +
> +		/* Sensors already enabled. Skip. */
> +		if ((reg & mask) == mask)

This is a bug. You have to do mask <<= SENSOR0_SHIFT; before reg & mask.

> +			return 0;
> +	}
> +
> +	mask <<= SENSOR0_SHIFT;
> +
>   	ret = regmap_write(priv->tm_map, CNTL_ADDR, reg | SW_RST);
>   	if (ret)
>   		return ret;
>   
> +	reg |= MEASURE_PERIOD;
> +
>   	if (priv->num_sensors > 1)
>   		reg |= mask | SLP_CLK_ENA | EN;
>   	else
> 

-- 
Warm Regards
Thara