Hello Felix,
On 04/07/2017 10:22 AM, Felix Brack wrote:
> Hello Jacek,
>
> On 06.04.2017 21:00, Jacek Anaszewski wrote:
>> Hi Pavel,
>>
>> On 04/06/2017 05:50 PM, Pavel Machek wrote:
>>> Hi!
>>>
>>>>> diff --git a/Documentation/devicetree/bindings/leds/leds-pca9532.txt b/Documentation/devicetree/bindings/leds/leds-pca9532.txt
>>>>> index 198f3ba..8374075 100644
>>>>> --- a/Documentation/devicetree/bindings/leds/leds-pca9532.txt
>>>>> +++ b/Documentation/devicetree/bindings/leds/leds-pca9532.txt
>>>>> @@ -17,6 +17,8 @@ Optional sub-node properties:
>>>>> - label: see Documentation/devicetree/bindings/leds/common.txt
>>>>> - type: Output configuration, see dt-bindings/leds/leds-pca9532.h (default NONE)
>>>>> - linux,default-trigger: see Documentation/devicetree/bindings/leds/common.txt
>>>>> + - default-state: see Documentation/devicetree/bindings/leds/common.txt
>>>>> + This property is only valid for sub-nodes of type <PCA9532_TYPE_LED>.
>>>>>
>>>>> Example:
>>>>> #include <dt-bindings/leds/leds-pca9532.h>
>>>>> @@ -33,6 +35,14 @@ Example:
>>>>> label = "pca:green:power";
>>>>> type = <PCA9532_TYPE_LED>;
>>>>> };
>>>>> + kernel-booting {
>>>>> + type = <PCA9532_TYPE_LED>;
>>>>> + default-state = "on";
>>>>> + };
>>>>> + sys-stat {
>>>>> + type = <PCA9532_TYPE_LED>;
>>>>> + default-state = "keep"; // don't touch, was set by U-Boot
>>>>> + };
>>>>
>>>> Adjusted above indentation to match the preceding lines.
>>>
>>>>> @@ -475,6 +494,16 @@ pca9532_of_populate_pdata(struct device *dev, struct device_node *np)
>>>>> of_property_read_u32(child, "type", &pdata->leds[i].type);
>>>>> of_property_read_string(child, "linux,default-trigger",
>>>>> &pdata->leds[i].default_trigger);
>>>>> + if (!of_property_read_string(child, "default-state", &state)) {
>>>>> + if (!strcmp(state, "on"))
>>>>> + pdata->leds[i].state = PCA9532_ON;
>>>>> + else if (!strcmp(state, "keep"))
>>>>> + pdata->leds[i].state = PCA9532_KEEP;
>>>>> + else if (!strcmp(state, "pwm0"))
>>>>> + pdata->leds[i].state = PCA9532_PWM0;
>>>>> + else if (!strcmp(state, "pwm1"))
>>>>> + pdata->leds[i].state = PCA9532_PWM1;
>>>>> + }
>>>>> if (++i >= maxleds) {
>>>>> of_node_put(child);
>>>>> break;
>>>
>>> This seems to look for "pwm0" and "pwm1" strings, which do not seem to
>>> be documented.
>>>
>>> Plus... is it useful to have default-state? We already have default
>>> trigger. If we keep the value by default (on PC, we do something like
>>> that) this patch should not be neccessary?
>>
>> Thanks for the heads-up. Dropping the patch for now.
>
> No, please do not drop the patch.
>
>> I guess that pwm0/1 got propagated to v2 by an omission.
>>
>
> Yes, I agree. However the two strings do not break anything and behave
> analog to the 'on' or 'keep' string. Though this code could be removed
> if absolutely necessary. An alternative would be to add a description
> for the strings. Just to be clear: these strings have nothing to with
> the exposition of device specific registers to the DT.
>
>> Regarding default-on: Felix, do you have any use case that require
>> default-on set to "keep"?
>>
>
> This patch is not about 'default-on' which is a value that could be
> assigned to the property 'linux,default-trigger' (according to DT
> bindings documentation file 'common.txt').
> My patch does not introduce anything new with the'keep' state, it rather
> completes the existing bindings according to the description in
> Documentation/devicetree/bindings/leds/common.txt which states:
>
> ....
> - default-state : The initial state of the LED. Valid values are "on",
> "off", and "keep". If the LED is already on or off and the default-state
> property is set the to same value, then no glitch should be produced
> where the LED momentarily turns off (or on). The "keep" setting will
> keep the LED at whatever its current state is, without producing a
> glitch. The default is off if this property is not present.
> ....
>
> One of my use cases is to turn a LED on by U-Boot. This LED must remain
> on until eventually, under certain conditions, some userland code
> changes it's state.
> Setting 'default-state' to 'keep' is how you can sort of tell the
> kernel, or better the driver, 'not to initialize the LED' which would
> turn it off.
Thanks for the explanation. Could you please sent v3 with removed pwm*
cases then?
--
Best regards,
Jacek Anaszewski
