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Date: Fri, 10 May 2013 12:05:59 -0400
From: Eduardo Valentin <eduardo.valentin@...com>
To: amit daniel kachhap <amit.daniel@...sung.com>
CC: Eduardo Valentin <eduardo.valentin@...com>,
<linux-pm@...r.kernel.org>, Zhang Rui <rui.zhang@...el.com>,
<linux-samsung-soc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, Kukjin Kim <kgene.kim@...sung.com>
Subject: Re: [PATCH V3 20/21] thermal: exynos: Support for TMU regulator defined
at device tree
On 09-05-2013 22:28, amit daniel kachhap wrote:
> Hi Eduardo,
>
> On Thu, May 9, 2013 at 8:14 PM, Eduardo Valentin
> <eduardo.valentin@...com> wrote:
>> On 07-05-2013 09:01, Amit Daniel Kachhap wrote:
>>> TMU probe function now checks for a device tree defined regulator.
>>> For compatibility reasons it is allowed to probe driver even without
>>> this regulator defined.
>>>
>>> Signed-off-by: Lukasz Majewski <l.majewski@...sung.com>
>>> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
>>> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
>>> ---
>>> .../devicetree/bindings/thermal/exynos-thermal.txt | 4 ++++
>>> drivers/thermal/samsung/exynos_tmu.c | 19 +++++++++++++++++++
>>> 2 files changed, 23 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/thermal/exynos-thermal.txt b/Documentation/devicetree/bindings/thermal/exynos-thermal.txt
>>> index 970eeba..ff62f7a 100644
>>> --- a/Documentation/devicetree/bindings/thermal/exynos-thermal.txt
>>> +++ b/Documentation/devicetree/bindings/thermal/exynos-thermal.txt
>>> @@ -14,6 +14,9 @@
>>> - interrupts : Should contain interrupt for thermal system
>>> - clocks : The main clock for TMU device
>>> - clock-names : Thermal system clock name
>>> +- vtmu-supply: This entry is optional and provides the regulator node supplying
>>> + voltage to TMU. If needed this entry can be placed inside
>>> + board/platform specific dts file.
>>>
>>> Example 1):
>>>
>>> @@ -25,6 +28,7 @@ Example 1):
>>> clocks = <&clock 383>;
>>> clock-names = "tmu_apbif";
>>> status = "disabled";
>>> + vtmu-supply = <&tmu_regulator_node>;
>>> };
>>>
>>> Example 2):
>>> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
>>> index 72446c9..b7c609a 100644
>>> --- a/drivers/thermal/samsung/exynos_tmu.c
>>> +++ b/drivers/thermal/samsung/exynos_tmu.c
>>> @@ -32,6 +32,7 @@
>>> #include <linux/of_address.h>
>>> #include <linux/of_irq.h>
>>> #include <linux/platform_device.h>
>>> +#include <linux/regulator/consumer.h>
>>> #include <linux/slab.h>
>>> #include <linux/workqueue.h>
>>> #include "exynos_thermal_common.h"
>>> @@ -52,6 +53,7 @@
>>> * @clk: pointer to the clock structure.
>>> * @temp_error1: fused value of the first point trim.
>>> * @temp_error2: fused value of the second point trim.
>>> + * @regulator: pointer to the TMU regulator structure.
>>> * @reg_conf: pointer to structure to register with core thermal.
>>> */
>>> struct exynos_tmu_data {
>>> @@ -65,6 +67,7 @@ struct exynos_tmu_data {
>>> struct mutex lock;
>>> struct clk *clk;
>>> u8 temp_error1, temp_error2;
>>> + struct regulator *regulator;
>>> struct thermal_sensor_conf *reg_conf;
>>> };
>>>
>>> @@ -501,10 +504,23 @@ static int exynos_map_dt_data(struct platform_device *pdev)
>>> struct exynos_tmu_data *data = platform_get_drvdata(pdev);
>>> struct exynos_tmu_platform_data *pdata = data->pdata;
>>> struct resource res;
>>> + int ret;
>>>
>>> if (!data)
>>> return -ENODEV;
>>>
>>> + /* Try enabling the regulator if found */
>>> + data->regulator = devm_regulator_get(&pdev->dev, "vtmu");
>>> + if (!IS_ERR(data->regulator)) {
>>> + ret = regulator_enable(data->regulator);
>>> + if (ret) {
>>> + dev_err(&pdev->dev, "failed to enable vtmu\n");
>>> + return ret;
>>> + }
>>> + } else {
>>> + dev_info(&pdev->dev, "Regulator node (vtmu) not found\n");
>>
>> Now that you have a bitfield for your features, shouldnt this become a
>> check? If the SoC requires the regulator, then it has to return a valid
>> regulator (regulator_get). Meaning, if your SoC version requires this
>> feature and the regulator_get returns an error, you must treat as an
>> error an not continue gracefuly.
>
> Earlier I also thought of using bit feature for this but then the
> regulator source usually depends upon the board design so each soc may
> have several boards. So regulator information is not part of SOC data.
> Since this information is there is in DT only so I left this part for
> the DT to handle.
>
Hmmm.. well, that is actually arguable. Take from driver perspective. If
a regulator is required for a device to work you have to make it a
requirement and not rely on whatever state the system has booted.
From previous discussions, I understood on of your chip versions
actually require a regulator to be activated in order to get the sensors
properly working. Is this understanding correct?
> Thanks,
> Amit Daniel
>>
>>> + }
>>> +
>>> data->id = of_alias_get_id(pdev->dev.of_node, "tmuctrl");
>>> if (data->id < 0)
>>> data->id = 0;
>>> @@ -669,6 +685,9 @@ static int exynos_tmu_remove(struct platform_device *pdev)
>>>
>>> clk_unprepare(data->clk);
>>>
>>> + if (!IS_ERR(data->regulator))
>>> + regulator_disable(data->regulator);
>>> +
>>> platform_set_drvdata(pdev, NULL);
>>>
>>> return 0;
>>>
>>
>>
>
>
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