From: Jacek Anaszewski <jacek.anaszewski@gmail.com>
To: Yauhen Kharuzhy <jekhor@gmail.com>, Pavel Machek <pavel@ucw.cz>
Cc: Hans de Goede <hdegoede@redhat.com>,
linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org
Subject: Re: [PATCH v2 1/2] leds: Add Intel Cherry Trail Whiskey Cove PMIC LEDs
Date: Fri, 15 Feb 2019 22:43:17 +0100 [thread overview]
Message-ID: <a79807bb-7826-6f2c-0738-7bddcc66cc5e@gmail.com> (raw)
In-Reply-To: <20190215072709.GD30250@jeknote.loshitsa1.net>
Hi Yauhen,
On 2/15/19 8:27 AM, Yauhen Kharuzhy wrote:
> On Fri, Feb 15, 2019 at 12:03:07AM +0100, Pavel Machek wrote:
>> Hi!
>>
>>>>>> I suggest that we deal with this special case by adding 3 custom
>>>>>> sysfs attributes:
>>>>>>
>>>>>> 1) "mode" which when read, prints, e.g. :
>>>>>> manual [on-when-charging]
>>>>>
>>>>> While this allows _user on console_ to control everything using echo,
>>>>> it is not suitable for applications trying to control LEDs.
>>>>>
>>>>> As there's nothing special about the case here, I believe we should
>>>>> have generic solution here.
>>>>>
>>>>> My preffered solution would be "hardware" trigger that leaves the LED
>>>>> in hardware control.
>>>>
>>>> As you explained in the parts which I snipped, there are many
>>>> devices which have a similar choice for a LED being under hw or
>>>> user control. I can see how this looks like a trigger and how we
>>>> could use the trigger API for this.
>>>>
>>>> I believe though, that if we implement a "virtual" (for lack of
>>>> a better word) trigger for this, that this should be done in the
>>>> LED core. I can envision this working like this:
>>>>
>>>> 1) Add a:
>>>>
>>>> hw_control_set(struct led_classdev *led_cdev, bool enable_hw_control);
>>>
>>> Please note that we have support for hw patterns in the pattern trigger.
>>> (see how drivers/leds/leds-sc27xx-bltc.c makes use of it for its
>>> breathing pattern).
>>> We have also support for hw blinking in timer trigger via blink_set op.
>>>
>>> In addition to that there is brightness_hw_changed sysfs attribute
>>> with led_classdev_notify_brightness_hw_changed() LED API.
>>>
>>> Couldn't they be used in concert to support the specific features
>>> of the device in question?
>>
>> I believe main issue here is this:
>>
>> Hardware can automatically control the LED according to the charging
>> status, or it can be used as normal software-controlled LED.
>>
>> I believe we should use trigger to select if hardware controls it or
>> not (and then add driver-specific files to describe the
>> details). Other proposal is in the mail thread, too.
>
> But there are two kinds of 'hardware control' here in discussion:
> 1:
> a) PMIC switching LED off/on/breathing/blinking reflected the charging
> state (charger is controlled by PMIC entirely without of
> software intervention) – 'hw controlled' mode
Can we detect when charging is activated?
> b) Software controls when LED is on/off/breathing/blinking but
> patterns are generated by PMIC – 'sw controlled' mode.
>
> 2:
> a) parameters of lighting (continuous/blinking/breathing) are
> set in the PMIC and the PMIC generates patterns
> b) blinking/breathing patterns are generated by the software
> entirely.
>
> It seems that we sometimes confuse this two kinds of hw control definitions
> in the discussion.
>
>
> The simple use case question: with this hardware and existing LED class
> API, what user/app should to do to make LED breathing with hw-generated
> pattern?
>
> As I see, user should activate 'pattern' trigger and write to its hw_pattern attribute...
> hm... big pattern which describes every step of breathing? Some
> simplified pattern which should be interpreted as 'enable the breathing
> an set its frequency' by driver? Which level of simplification will be
> suitable? Which criteria of pattern rejection should be?
Please see my reply to Hans. We need some simplified device specific
syntax of hw_pattern for this device, similarly like in:
Documentation/ABI/testing/sysfs-class-led-driver-sc27xx
--
Best regards,
Jacek Anaszewski
next prev parent reply other threads:[~2019-02-15 21:43 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 20:58 [PATCH v2 0/2] Intel Cherry Trail Whiskey Cove LEDs support Yauhen Kharuzhy
2019-02-12 20:59 ` [PATCH v2 1/2] leds: Add Intel Cherry Trail Whiskey Cove PMIC LEDs Yauhen Kharuzhy
2019-02-13 22:43 ` Hans de Goede
2019-02-13 23:07 ` Pavel Machek
2019-02-13 23:25 ` Hans de Goede
2019-02-13 23:38 ` Pavel Machek
2019-02-14 9:57 ` Hans de Goede
2019-02-14 11:14 ` Pavel Machek
2019-02-14 11:31 ` Hans de Goede
2019-02-14 12:28 ` Pavel Machek
2019-02-15 21:41 ` Jacek Anaszewski
2019-02-15 23:26 ` Pavel Machek
2019-02-14 21:46 ` Jacek Anaszewski
2019-02-14 23:03 ` Pavel Machek
2019-02-15 7:27 ` Yauhen Kharuzhy
2019-02-15 21:43 ` Jacek Anaszewski [this message]
2019-02-16 11:26 ` Yauhen Kharuzhy
2019-02-15 11:27 ` Hans de Goede
2019-02-15 13:02 ` Pavel Machek
2019-02-15 21:42 ` Jacek Anaszewski
2019-02-15 22:26 ` Hans de Goede
2019-02-15 22:31 ` Jacek Anaszewski
2019-02-15 23:14 ` Hans de Goede
2019-02-16 17:02 ` Jacek Anaszewski
2019-02-16 19:01 ` Hans de Goede
2019-02-16 19:37 ` Pavel Machek
2019-02-16 20:55 ` Hans de Goede
2019-02-17 0:08 ` Pavel Machek
2019-02-17 14:10 ` Hans de Goede
2019-02-17 17:45 ` Pavel Machek
2019-02-18 11:12 ` Hans de Goede
2019-02-18 21:59 ` Jacek Anaszewski
2019-02-16 21:54 ` Jacek Anaszewski
2019-02-16 22:03 ` Hans de Goede
2019-02-17 12:40 ` Jacek Anaszewski
2019-02-14 11:28 ` Pavel Machek
2019-02-14 21:34 ` Yauhen Kharuzhy
2019-02-14 6:55 ` Yauhen Kharuzhy
2019-02-14 10:04 ` Hans de Goede
2019-02-12 20:59 ` [PATCH v2 2/2] mfd: Add leds MFD cell for intel_soc_pmic_chtwc Yauhen Kharuzhy
2019-02-13 21:24 ` Jacek Anaszewski
2019-03-20 9:56 ` Lee Jones
2019-03-20 9:57 ` Lee Jones
2019-04-21 19:28 ` [PATCH v2 0/2] Intel Cherry Trail Whiskey Cove LEDs support Hans de Goede
2019-04-24 18:32 ` Yauhen Kharuzhy
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