lkml.org 
[lkml]   [2018]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v8 2/2] leds: sc27xx: Add pattern_set/clear interfaces for LED controller
On 5 September 2018 at 10:43, Baolin Wang <baolin.wang@linaro.org> wrote:
> Hi Jacek,
>
> On 5 September 2018 at 04:19, Jacek Anaszewski
> <jacek.anaszewski@gmail.com> wrote:
>> Hi Baolin,
>>
>> On 09/04/2018 01:01 PM, Baolin Wang wrote:
>>> This patch implements the 'pattern_set'and 'pattern_clear'
>>> interfaces to support SC27XX LED breathing mode.
>>>
>>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
>>> ---
>>> Changes from v7:
>>> - Add its own ABI documentation file.
>>>
>>> Changes from v6:
>>> - None.
>>>
>>> Changes from v5:
>>> - None.
>>>
>>> Changes from v4:
>>> - None.
>>>
>>> Changes from v3:
>>> - None.
>>>
>>> Changes from v2:
>>> - None.
>>>
>>> Changes from v1:
>>> - Remove pattern_get interface.
>>> ---
>>> .../ABI/testing/sysfs-class-led-driver-sc27xx | 11 +++
>>> drivers/leds/leds-sc27xx-bltc.c | 94 ++++++++++++++++++++
>>> 2 files changed, 105 insertions(+)
>>> create mode 100644 Documentation/ABI/testing/sysfs-class-led-driver-sc27xx
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-class-led-driver-sc27xx b/Documentation/ABI/testing/sysfs-class-led-driver-sc27xx
>>> new file mode 100644
>>> index 0000000..ecef3ba
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-class-led-driver-sc27xx
>>> @@ -0,0 +1,11 @@
>>> +What: /sys/class/leds/<led>/hw_pattern
>>> +Date: September 2018
>>> +KernelVersion: 4.20
>>> +Description:
>>> + Specify a hardware pattern for the SC27XX LED. For the SC27XX
>>> + LED controller, it only supports 4 hardware patterns to configure
>>
>> If I understand it correctly then the four components: low, rise, high,
>> and fall time make a single pattern. So calling it "4 hardware patterns"
>> can be misleading. Below you're using "stage" notion - it would be good
>> to use it consequently on the whole span of this document.
>
> Sure. I will modify the documentation to avoid misleading words.
>
>>
>>> + the low time, rise time, high time and fall time for the breathing
>>> + mode, and each stage duration unit is 125ms. So the format of
>>> + the hardware pattern values should be:
>>
>> I'd be more precise here:
>>
>> Min stage duration: ???
>> Max stage duration: ???
>> Stage duration step: 125 ms
>
> OK.
>
>>
>>> + "brightness_1 duration_1 brightness_2 duration_2 brightness_3
>>> + duration_3 brightness_4 duration_4".
>>
>> Looking at sc27xx_led_pattern_set() it doesn't seem like you would
>> use brightnesses other then brightness_1. I assume that the low
>> brightness is fixed to 0 and the high brightness is the brightness_1.
>> If yes, than we don't need brightnesses in this pattern definition,
>> since the current brightness will suffice.
>>
>> You'd need to alter the hw_pattern description to say that the
>> brightness currently set is to be used as a high brightness, and the
>> hw_pattern for this driver consists only of the four delta_t components.
>
> Sorry for confusing here. For SC27XX LED, the 4 stages use one same
> brightness. To be compatible with the hardware pattern format, so we
> force to set one brightness for each stage. I will add some comments
> to explain the LED expects the same brightness for each stage instead
> of using the current brightness file which is not used for our
> breathing mode.
>
>>
>> This is clear example of what I had on mind when having doubts
>> about using tuples for pattern_set.
>>
>> Alternatively, if we want to enforce tuples format for hw_pattern,
>> and if we want to be consistent - we'd need to require defining target
>> brightness for each stage properly, i.e.
>>
>> echo "100 500 100 500 0 500 0 500" > pattern

After more thinking, I will change the description to reflect the real
brightness according to your suggestion. Please see my new patch.
Thanks.

>>
>> Which would mean:
>>
>> 1. Rise from brightness 0 to 100 for 500 ms.
>> 2. Keep brightness 100 for 500 ms.
>> 3. Fall from brightness 100 to 0 for 500 ms.
>> 4. Keep brightness 0 for 500 ms.
>>
>> --
>> Best regards,
>> Jacek Anaszewski
>
>
>
> --
> Baolin Wang
> Best Regards



--
Baolin Wang
Best Regards

\
 
 \ /
  Last update: 2018-09-05 08:52    [W:0.058 / U:4.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site