From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH v5 1/2] leds: core: Introduce LED pattern trigger Date: Fri, 24 Aug 2018 22:12:27 +0200 Message-ID: <20180824201227.GB17146@amd> References: <1dc5d394324b2bf1ffe229b8e42691fab6d749e0.1533556992.git.baolin.wang@linaro.org> <20180824101145.GA1510@amd> <9bb7ac19-36a6-d11a-6d46-fc65c2026201@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="p2kqVDKq5asng8Dg" Return-path: Content-Disposition: inline In-Reply-To: <9bb7ac19-36a6-d11a-6d46-fc65c2026201@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 --p2kqVDKq5asng8Dg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri 2018-08-24 21:49:50, Jacek Anaszewski wrote: > Hi Pavel, >=20 > On 08/24/2018 12:11 PM, Pavel Machek wrote: > > Hi! > >=20 > >> I think that it would be more flexible if software pattern fallback > >> was applied in case of pattern_set failure. Otherwise, it would > >> lead to the situation where LED class devices that support hardware > >> blinking couldn't be applied the same set of patterns as LED class > >> devices that don't implement pattern_set. The latter will always have = to > >> resort to using software pattern engine which will accept far greater > >> amount of pattern combinations. > >> > >> In this case we need to discuss on what basis the decision will be > >> made on whether hardware or software engine will be used. > >> > >> Possible options coming to mind: > >> - an interface will be provided to determine max difference between > >> the settings supported by the hardware and the settings requested by > >> the user, that will result in aligning user's setting to the hardware > >> capabilities > >> - the above alignment rate will be predefined instead > >> - hardware engine will be used only if user requests supported settings > >> on the whole span of the requested pattern > >> - in each of the above cases it would be worth to think of the > >> interface to show the scope of the settings supported by hardware > >=20 > > I'd recommend keeping it simple. We use hardware engine if driver > > author thinks pattern is "close enough". >=20 > The thing is that in the ledtrig-pattern v5 implementation there > is no option of using software fallback if pattern_set op > is initialized: >=20 > + if (led_cdev->pattern_set) { > + return led_cdev->pattern_set(led_cdev, data->patterns, > + data->npatterns, data->repeat); > + } Yeah, that sounds wrong. (Sorry I did not pay enough attention). It pattern_set() returns special error code, it should just continue and use software pattern fallback. Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --p2kqVDKq5asng8Dg Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAluAZqsACgkQMOfwapXb+vL6qACfUF2J7US+MKxUh5rbg3o0Pz2L w8EAnjdHFhPzPYHAXmpCrKfW4jdnOlLp =XQ6Y -----END PGP SIGNATURE----- --p2kqVDKq5asng8Dg--