From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [PATCH v2 1/2] leds: Add Intel Cherry Trail Whiskey Cove PMIC LEDs Date: Sat, 16 Feb 2019 20:01:49 +0100 Message-ID: References: <20190212205901.13037-1-jekhor@gmail.com> <20190212205901.13037-2-jekhor@gmail.com> <1df39a63-533f-bb68-a056-a0241f148be9@redhat.com> <20190213230731.GA8557@amd> <42078a81-e32e-81b7-528f-d1adb60d31c3@redhat.com> <20190213233806.GA11867@amd> <562e2acd-a60a-2aea-4050-6d9414d23a4e@redhat.com> <20190214111423.GE6132@amd> <92cf09b8-726d-4f1b-94ba-368a66af2246@redhat.com> <2b6faaa5-b21e-a512-de7d-ca21be5045fc@gmail.com> <20190214230307.GA17358@amd> <2a5e2002-e5f1-6da3-8a43-317801b69657@redhat.com> <3d5407a7-9458-f071-a1d5-511b09678e20@gmail.com> <87a21c4e-8e5e-c180-2ff3-eb8170746e71@redhat.com> <80971bc3-1193-83ed-913a-12f6217016c8@gmail.com> <8a263266-a41f-c916-e990-02d04de9b5d0@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8a263266-a41f-c916-e990-02d04de9b5d0@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Jacek Anaszewski , Pavel Machek Cc: Yauhen Kharuzhy , linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org List-Id: linux-leds@vger.kernel.org Hi, On 2/16/19 6:02 PM, Jacek Anaszewski wrote: > Hi Hans, > > On 2/16/19 12:14 AM, Hans de Goede wrote: >> Hi, >> >> On 2/15/19 11:31 PM, Jacek Anaszewski wrote: >>> On 2/15/19 11:26 PM, Hans de Goede wrote: >> >> >> >>>> I think that should work fine, which means that we can use the timer and >>>> pattern trigger support for the blinking and breathing modes. >>>> >>>> That still leaves the switching between user and hw-control modes, >>>> as discussed the hw-controlled mode could be modelled as a new "hardware" >>>> trigger, but then we cannot choose between on/blink/breathing when >>>> in hw-controlled mode. As Pavel mentioned, that would require some >>>> sort of composed trigger, where we have both the hardware and >>>> timer triggers active for example. >>>> >>>> I think it might be easier to just allow turning on/off the hardware >>>> control mode through a special "hardware_control" sysfs attribute and >>>> then use the existing timer and pattern triggers for blinking / breathing. >>> >>> Pattern trigger exposes pattern file by default and hw_pattern if >>> pattern_set/get ops are provided. Writing them enables software and >>> hardware pattern respectively. >> >> This is not about software vs hardware pattern. >> >> There are 2 *orthogonal*, separate problems/challenges with this LED controller: >> >> 1) It has hardware blinking and breathing, as discussed this can be >> controlled through the timer and pattern triggers, so this problem >> is solved. >> >> 2) It has 2 operating modes: >> >> a) Automatic/hardware controlled, in this mode the LED is turned >> off or on (where on can be continues on, blinking or breathing) >> by the hardware itself, when in this mode we / userspace is not >> in control of the LED >> >> b) Manual/user controlled mode, in this mode we / userspace can >> control of the LED. >> >> Currently there is no API in the ledclass to switch a LED from >> automatic controlled to user controlled and back, This is what >> the proposed hardware trigger was for, to switch to automatic >> mode. A problem with this is that we still want to be able >> to chose between continues on, blinking or breathing (when on), >> configure the max brightness, etc. > > Yes, we do have the API to switch a LED from automatic (hardware > accelerated) control to software control and back. This is pattern > trigger, which exposes two files for setting pattern: pattern > and hw_pattern. Writing pattern file switches the device to software > control mode and writing hw_pattern switches it to the hardware control, > with the possibility of defining device specific ABI syntax to enable > particular pattern (blinking, breathing or event permanently on > in case of this device). OK, I see. So we would use the hw_pattern for this and the driver would implement the pattern_set led_classdev callback. The pattern_set callback would then expect 6 brightness/time tuples with the following meaning for the time part of each tupple tupple0: charging blinking_on_time tupple1: charging blinking_off_time tupple2: charging breathing_time tupple3: manual blinking_on_time tupple4: manual blinking_off_time tupple5: manual breathing_time Where only the times in tupple 0-2; or the times in 3-5 can be non-zero. Having non zero times for both some charging and some manual values is not allowed. If a breathing time is set, none of the other times may be non 0. If blinkig_on and blinking_off are used then breathing_time must be 0. When configured to blink then blinking_off must be either 0 (continuously on); or it must be the same as blinking_on. I believe this will work, does this sound ok to you ? Regards, Hans