Hi,
On 05/09/2018 04:25 PM, Pavel Machek wrote:
On Tue 2018-05-08 13:39:45, Baolin Wang wrote:
From: Xiaotong Lu <xiaotong.lu@xxxxxxxxxxxxxx>
This patch adds Spreadtrum SC27xx PMIC series breathing light controller
driver, which can support 3 LEDs. Each LED can work at normal PWM mode
and breathing mode.
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..22166fb
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-driver-sc27xx
@@ -0,0 +1,19 @@
+What: /sys/class/leds/<led>/rise_time
+What: /sys/class/leds/<led>/high_time
+What: /sys/class/leds/<led>/fall_time
+What: /sys/class/leds/<led>/low_time
+Date: May 2018
+KernelVersion: 4.18
+Contact: Xiaotong Lu <xiaotong.lu@xxxxxxxxxxxxxx>
+Description:
+ Set the pattern generator rise, high, fall and low
+ times (0..63). It's unit is 0.125s, it should be > 0.
+
+ 1 - 125 ms
+ 2 - 250 ms
+ 3 - 375 ms
+ ...
+ ...
+ ...
+ 62 - 7.75 s
+ 63 - 7.875 s
How does this interact with triggers? With manually setting
brightness? Are the pattern generators independend for the LEDs?
Can you generate white breathing pattern? If so, how?
How do you select between normal and breathing modes?
I'd specify times in miliseconds or something, this is way too
hardware specific.
Agreed.
Now... functionality like this is common between many LED
controllers. N900 could do this kind of "breathing", too, and it also
supports other patterns.
I believe we need interface common between different LED controllers.
And I guess it would be easiest if you dropped this part from initial
merge.
I disagree here. We already had the same discussion at the occasion
of the patch [0] and it turned out to be a dead-end [1]. Now we have
neither the driver nor the generic pattern interface.
We also already have some older LED class drivers that implement custom
pattern interfaces (e.g. drivers/leds/leds-lm3533.c) and the same
approach can be applied in this case.
Regarding interaction with triggers - we could disable pattern
on setting any trigger and return -EBUSY from the pattern
interface if led_cdev->trigger is not NULL.
[0] https://lkml.org/lkml/2017/3/23/33
[1] https://lkml.org/lkml/2017/11/15/27
--
Best regards,
Jacek Anaszewski
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