On 19-12-2013 17:16, Anson Huang wrote:
> Thermal sensor needs pll3_usb_otg when measuring temperature,
> otherwise the temperature read will be incorrect, so need to
> enable this clk before sensor working, for alarm function,
> as hardware will take measurement periodically, so we should
> keep this clk always on once alarm function is enabled.
>
> Signed-off-by: Anson Huang <b20788@xxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/thermal/imx-thermal.txt | 4 ++++
> drivers/thermal/imx_thermal.c | 18 ++++++++++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/thermal/imx-thermal.txt b/Documentation/devicetree/bindings/thermal/imx-thermal.txt
> index 541c25e..1f0f672 100644
> --- a/Documentation/devicetree/bindings/thermal/imx-thermal.txt
> +++ b/Documentation/devicetree/bindings/thermal/imx-thermal.txt
> @@ -8,10 +8,14 @@ Required properties:
> calibration data, e.g. OCOTP on imx6q. The details about calibration data
> can be found in SoC Reference Manual.
>
> +Optional properties:
> +- clocks : thermal sensor's clock source.
> +
> Example:
>
> tempmon {
> compatible = "fsl,imx6q-tempmon";
> fsl,tempmon = <&anatop>;
> fsl,tempmon-data = <&ocotp>;
> + clocks = <&clks 172>;
> };
> diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
> index 1d6c801..c2b8173 100644
> --- a/drivers/thermal/imx_thermal.c
> +++ b/drivers/thermal/imx_thermal.c
> @@ -7,6 +7,7 @@
> *
> */
>
> +#include <linux/clk.h>
> #include <linux/cpu_cooling.h>
> #include <linux/cpufreq.h>
> #include <linux/delay.h>
> @@ -73,6 +74,7 @@ struct imx_thermal_data {
> unsigned long last_temp;
> bool irq_enabled;
> int irq;
> + struct clk *thermal_clk;
> };
>
> static void imx_set_alarm_temp(struct imx_thermal_data *data,
> @@ -457,6 +459,22 @@ static int imx_thermal_probe(struct platform_device *pdev)
> return ret;
> }
>
There are several reg writes before this point. Are you sure you won't
need this clock for performing those operations?
> + 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 */
>
Don't you need to release the clock when .remove is called either on
driver or device removal?
What about suspend / resume path? Do you want to keep this clock on when
suspending? Is it gonna work or prevent your system to enter low power
states?
--
You have got to be excited about what you are doing. (L. Lamport)
Eduardo Valentin
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