From mboxrd@z Thu Jan 1 00:00:00 1970 From: heiner.kallweit@web.de (Heiner Kallweit) Date: Wed, 08 Oct 2014 07:48:45 +0200 Subject: [PATCH v2] imx: thermal: imx_get_temp might be called before sensor clock is prepared Message-ID: <5434D03D.7090408@web.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. v2: revised error path. Bail out and tidy up properly if we can't get the clock or fail to enable it. Signed-off-by: Heiner Kallweit --- drivers/thermal/imx_thermal.c | 39 +++++++++++++++++++++++---------------- 1 file changed, 23 insertions(+), 16 deletions(-) diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c index 461bf3d..faf5d88 100644 --- a/drivers/thermal/imx_thermal.c +++ b/drivers/thermal/imx_thermal.c @@ -521,6 +521,28 @@ 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); + 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, @@ -531,26 +553,11 @@ 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 */ -- 2.1.2