linux-kernel - Re: [PATCH 2/3] thermal: qoriq_thermal: only enable supported sensors

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Date:   Wed, 31 May 2023 14:35:06 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Peng Fan <peng.fan@....com>,
        "Peng Fan (OSS)" <peng.fan@....nxp.com>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
Cc:     "amitk@...nel.org" <amitk@...nel.org>,
        "rui.zhang@...el.com" <rui.zhang@...el.com>,
        "andrew.smirnov@...il.com" <andrew.smirnov@...il.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Alice Guo <alice.guo@....com>
Subject: Re: [PATCH 2/3] thermal: qoriq_thermal: only enable supported sensors

On 31/05/2023 14:05, Peng Fan wrote:
>> Subject: Re: [PATCH 2/3] thermal: qoriq_thermal: only enable supported
>> sensors
>>
>> On 16/05/2023 10:37, Peng Fan (OSS) wrote:
>>> From: Peng Fan <peng.fan@....com>
>>>
>>> There are MAX 16 sensors, but not all of them supported. Such as
>>> i.MX8MQ, there are only 3 sensors. Enabling all 16 sensors will touch
>>> reserved bits from i.MX8MQ reference mannual, and TMU will stuck,
>>> temperature will not update anymore.
>>>
>>> Fixes: 45038e03d633 ("thermal: qoriq: Enable all sensors before
>>> registering them")
>>> Signed-off-by: Peng Fan <peng.fan@....com>
>>> ---
>>>    drivers/thermal/qoriq_thermal.c | 30 +++++++++++++++++++-----------
>>>    1 file changed, 19 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/thermal/qoriq_thermal.c
>>> b/drivers/thermal/qoriq_thermal.c index b806a0929459..53748c4a5be1
>>> 100644
>>> --- a/drivers/thermal/qoriq_thermal.c
>>> +++ b/drivers/thermal/qoriq_thermal.c
>>> @@ -31,7 +31,6 @@
>>>    #define TMR_DISABLE	0x0
>>>    #define TMR_ME		0x80000000
>>>    #define TMR_ALPF	0x0c000000
>>> -#define TMR_MSITE_ALL	GENMASK(15, 0)
>>>
>>>    #define REGS_TMTMIR	0x008	/* Temperature measurement
>> interval Register */
>>>    #define TMTMIR_DEFAULT	0x0000000f
>>> @@ -105,6 +104,11 @@ static int tmu_get_temp(struct
>> thermal_zone_device *tz, int *temp)
>>>    	 * within sensor range. TEMP is an 9 bit value representing
>>>    	 * temperature in KelVin.
>>>    	 */
>>> +
>>> +	regmap_read(qdata->regmap, REGS_TMR, &val);
>>> +	if (!(val & TMR_ME))
>>> +		return -EAGAIN;
>>
>> How is this change related to what is described in the changelog?
> 
> devm_thermal_zone_of_sensor_register will invoke get temp,
> since we reverted the 45038e03d633 did, we need to check TMR_ME
> to avoid return invalid temperature.


 From a higher perspective if the sensor won't be enabled, then the 
thermal zone should not be registered, the get_temp won't happen on a 
disabled sensor and this test won't be necessary, no ?

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