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SubjectRe: [PATCH] thermal: imx: correct suspend/resume flow
Date


Sent from Anson's iPhone

> 在 2013年12月23日,22:28,"Shawn Guo" <shawn.guo@linaro.org> 写道:
>
>> On Mon, Dec 23, 2013 at 03:51:58PM -0500, Anson Huang wrote:
>> Current imx thermal sensor's suspend function will return fail if
>> thermal sensor is always enabled, but because alarm function is enabled,
>> thermal sensor will be always enabled as well, hence break system's suspend,
>> this patch will disable thermal sensor before suspend and re-enable it
>> after resume, it fixes the failure of suspend/resume caused by thermal driver.
>
> We should probably make it clear in the commit log that it's a
> regression caused by commit 37713a1 (thermal: imx: implement thermal
> alarm interrupt handling).

agreed, will improve the commit log in V2.

>
>>
>> Signed-off-by: Anson Huang <b20788@freescale.com>
>> ---
>> drivers/thermal/imx_thermal.c | 31 +++++++++++++++++--------------
>> 1 file changed, 17 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
>> index cbb16f3..9a9a6c2 100644
>> --- a/drivers/thermal/imx_thermal.c
>> +++ b/drivers/thermal/imx_thermal.c
>> @@ -510,27 +510,30 @@ static int imx_thermal_suspend(struct device *dev)
>> {
>> struct imx_thermal_data *data = dev_get_drvdata(dev);
>> struct regmap *map = data->tempmon;
>> - u32 val;
>>
>> - regmap_read(map, TEMPSENSE0, &val);
>> - if ((val & TEMPSENSE0_POWER_DOWN) == 0) {
>> - /*
>> - * If a measurement is taking place, wait for a long enough
>> - * time for it to finish, and then check again. If it still
>> - * does not finish, something must go wrong.
>> - */
>> - udelay(50);
>> - regmap_read(map, TEMPSENSE0, &val);
>> - if ((val & TEMPSENSE0_POWER_DOWN) == 0)
>> - return -ETIMEDOUT;
>> - }
>> + /*
>> + * Need to disable thermal sensor, otherwise, when thermal core
>> + * try to get temperature before thermal sensor resume, a wrong
>> + * temperature will be read as the thermal sensor is powered
>> + * down.
>> + */
>> + regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_MEASURE_TEMP);
>> + regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);
>> + data->mode = THERMAL_DEVICE_DISABLED;
>
> Is it really necessary to update data->mode through suspend/resume
> cycle?

Yes, as the thermal core may try to get temperature before imx thermal sensor resume, if not setting its mode to disabled, thermal core will get a wrong temp and caused system power off by mistake, as the get_temp function will decide whether to power up thermal core according to its mode.

>
> Shawn
>
>>
>> return 0;
>> }
>>
>> static int imx_thermal_resume(struct device *dev)
>> {
>> - /* Nothing to do for now */
>> + struct imx_thermal_data *data = dev_get_drvdata(dev);
>> + struct regmap *map = data->tempmon;
>> +
>> + /* Enabled thermal sensor after resume */
>> + regmap_write(map, TEMPSENSE0 + REG_CLR, TEMPSENSE0_POWER_DOWN);
>> + regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_MEASURE_TEMP);
>> + data->mode = THERMAL_DEVICE_ENABLED;
>> +
>> return 0;
>> }
>> #endif
>> --
>> 1.7.9.5
>
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