LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jacek Anaszewski <jacek.anaszewski@gmail.com>
To: Pavel Machek <pavel@ucw.cz>, Baolin Wang <baolin.wang@linaro.org>
Cc: robh+dt@kernel.org, mark.rutland@arm.com,
	xiaotong.lu@spreadtrum.com, broonie@kernel.org,
	linux-leds@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] leds: Add Spreadtrum SC27xx breathing light controller driver
Date: Wed, 9 May 2018 21:40:35 +0200	[thread overview]
Message-ID: <bddc1f89-8c2c-ba6e-3c7e-d89710ed5424@gmail.com> (raw)
In-Reply-To: <20180509142539.GB25131@amd>

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@spreadtrum.com>
>>
>> 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@spreadtrum.com>
>> +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

  reply	other threads:[~2018-05-09 19:42 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-08  5:39 [PATCH v2 1/2] dt-bindings: leds: Add SC27xx breathing light controller documentation Baolin Wang
2018-05-08  5:39 ` [PATCH v2 2/2] leds: Add Spreadtrum SC27xx breathing light controller driver Baolin Wang
2018-05-08 20:54   ` Jacek Anaszewski
2018-05-09  2:34     ` Baolin Wang
2018-05-09 14:25   ` Pavel Machek
2018-05-09 19:40     ` Jacek Anaszewski [this message]
2018-05-10 11:37       ` Pavel Machek
2018-05-10 19:41         ` Jacek Anaszewski
2018-05-12  8:35           ` Pavel Machek
2018-05-12 20:44             ` Jacek Anaszewski
2018-05-13  2:19               ` Baolin Wang
2018-06-21  7:25               ` Baolin Wang
2018-05-10  3:12     ` Baolin Wang
2018-05-08 15:43 ` [PATCH v2 1/2] dt-bindings: leds: Add SC27xx breathing light controller documentation Rob Herring
2018-05-09 14:25 ` Pavel Machek
2018-05-09 20:09   ` Jacek Anaszewski
2018-05-10  1:55   ` Baolin Wang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=bddc1f89-8c2c-ba6e-3c7e-d89710ed5424@gmail.com \
    --to=jacek.anaszewski@gmail.com \
    --cc=baolin.wang@linaro.org \
    --cc=broonie@kernel.org \
    --cc=devicetree@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-leds@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=pavel@ucw.cz \
    --cc=robh+dt@kernel.org \
    --cc=xiaotong.lu@spreadtrum.com \
    --subject='Re: [PATCH v2 2/2] leds: Add Spreadtrum SC27xx breathing light controller driver' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).