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imx: thermal: imx_get_temp might be called before sensor clock is prepared

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imx_get_temp might be called before the sensor clock is prepared
thus resulting in a timeout of the first attempt to read temp:
thermal thermal_zone0: failed to read out thermal zone 0
Happened to me on a Utilite Standard with IMX6 Dual SoC.

Reason is that in imx_thermal_probe thermal_zone_device_register
is called before the sensor clock is prepared.
thermal_zone_device_register however calls
thermal_zone_device_update which eventually calls imx_get_temp.

Fix this by preparing the clock before calling
thermal_zone_device_register.

Signed-off-by: Heiner Kallweit <heiner.kallweit@web.de>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
This commit is contained in:
Heiner Kallweit 2014-11-08 20:35:54 +01:00 committed by Eduardo Valentin
parent 1d6a277757
commit 90a21ff582
1 changed files with 25 additions and 16 deletions
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41
drivers/thermal/imx_thermal.c
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@ -525,6 +525,30 @@ static int imx_thermal_probe(struct platform_device *pdev)
return ret;
}
data->thermal_clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(data->thermal_clk)) {
ret = PTR_ERR(data->thermal_clk);
if (ret != -EPROBE_DEFER)
dev_err(&pdev->dev,
"failed to get thermal clk: %d\n", ret);
cpufreq_cooling_unregister(data->cdev);
return ret;
}
/*
* Thermal sensor needs clk on to get correct value, normally
* we should enable its clk before taking measurement and disable
* clk after measurement is done, but if alarm function is enabled,
* hardware will auto measure the temperature periodically, so we
* need to keep the clk always on for alarm function.
*/
ret = clk_prepare_enable(data->thermal_clk);
if (ret) {
dev_err(&pdev->dev, "failed to enable thermal clk: %d\n", ret);
cpufreq_cooling_unregister(data->cdev);
return ret;
}
data->tz = thermal_zone_device_register("imx_thermal_zone",
IMX_TRIP_NUM,
BIT(IMX_TRIP_PASSIVE), data,
@ -535,26 +559,11 @@ static int imx_thermal_probe(struct platform_device *pdev)
ret = PTR_ERR(data->tz);
dev_err(&pdev->dev,
"failed to register thermal zone device %d\n", ret);
clk_disable_unprepare(data->thermal_clk);
cpufreq_cooling_unregister(data->cdev);
return ret;
}
data->thermal_clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(data->thermal_clk)) {
dev_warn(&pdev->dev, "failed to get thermal clk!\n");
} else {
/*
* Thermal sensor needs clk on to get correct value, normally
* we should enable its clk before taking measurement and disable
* clk after measurement is done, but if alarm function is enabled,
* hardware will auto measure the temperature periodically, so we
* need to keep the clk always on for alarm function.
*/
ret = clk_prepare_enable(data->thermal_clk);
if (ret)
dev_warn(&pdev->dev, "failed to enable thermal clk: %d\n", ret);
}
/* Enable measurements at ~ 10 Hz */
regmap_write(map, TEMPSENSE1 + REG_CLR, TEMPSENSE1_MEASURE_FREQ);
measure_freq = DIV_ROUND_UP(32768, 10); /* 10 Hz */