From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH v14 1/2] leds: core: Introduce LED pattern trigger Date: Wed, 10 Oct 2018 18:00:48 +0200 Message-ID: <20181010160041.GA22121@amd> References: <9bf6236e-83af-7156-b26b-7d88ece2d81e@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="pvezYHf7grwyp3Bc" Return-path: Content-Disposition: inline In-Reply-To: <9bf6236e-83af-7156-b26b-7d88ece2d81e@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Jacek Anaszewski Cc: Baolin Wang , rteysseyre@gmail.com, bjorn.andersson@linaro.org, broonie@kernel.org, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-leds@vger.kernel.org --pvezYHf7grwyp3Bc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! [Oops. I wrote this but forgot to send it? Anyway.. I guess it is redundant now.] > > +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern > > @@ -0,0 +1,76 @@ > > +What: /sys/class/leds//pattern > > +Date: September 2018 > > +KernelVersion: 4.20 > > +Description: > > + Specify a software pattern for the LED, that supports altering > > + the brightness for the specified duration with one software > > + timer. It can do gradual dimming and constant brightness. > > + > > + The pattern is given by a series of tuples, of brightness and > > + duration (ms). The LED is expected to traverse the series and > > + each brightness value for the specified duration. Duration of > > + 0 means brightness should immediately change to new value. > > + > > + 1. When doing gradual dimming, the led brightness will be updated > > + every 50 milliseconds, so the duration of each step should not > > + less than 50 milliseconds. >=20 > I'd like to avoid this constraint. Lowest supported delta_t should be 1. >=20 > We should only prevent entering dimming mode if current delta_t > is lower than UPDATE_INTERVAL. I agree that documenting it like this is strange. I don't think this should be part of ABI as we may want to adjust it in the future. > I also propose to make the dimming interval configurable via sysfs > dimming_interval file. I believe we should provide "right" dimming_interval. 50msec sounds good. If we find it is too low / too high, we might want to adjust it. If we find out that different users need different values, I guess we can still add "dimming_interval" knob, but I'd suggest waiting until such need arises. [Now, I don't have strong feelings here, and patch would probably be okay with me even if it has dimming_interval, but I'd prefer to keep it simple. We are at v14 of the patch...] Thanks, Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --pvezYHf7grwyp3Bc Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlu+IjAACgkQMOfwapXb+vJKGACgsHAAydYbN5GADkbD3KjEsy91 qKIAn3vRLOcAeeemxCOYBEwNIcLUlrIG =Y0m2 -----END PGP SIGNATURE----- --pvezYHf7grwyp3Bc--