From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A7226C31E51 for ; Tue, 18 Jun 2019 12:02:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 84FAE20673 for ; Tue, 18 Jun 2019 12:02:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726505AbfFRMC0 (ORCPT ); Tue, 18 Jun 2019 08:02:26 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:50005 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725913AbfFRMCZ (ORCPT ); Tue, 18 Jun 2019 08:02:25 -0400 Received: by atrey.karlin.mff.cuni.cz (Postfix, from userid 512) id 8058C80329; Tue, 18 Jun 2019 14:02:11 +0200 (CEST) Date: Tue, 18 Jun 2019 14:02:21 +0200 From: Pavel Machek To: Matthias Kaehlcke Cc: Heiko Stuebner , Rob Herring , Mark Rutland , linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Enric Balletbo i Serra , Douglas Anderson Subject: Re: [PATCH] Revert "ARM: dts: rockchip: set PWM delay backlight settings for Minnie" Message-ID: <20190618120221.GA20524@amd> References: <20190614224533.169881-1-mka@chromium.org> <20190616154143.GA28583@atrey.karlin.mff.cuni.cz> <20190617161625.GR137143@google.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="3MwIy2ne0vdjdPXF" Content-Disposition: inline In-Reply-To: <20190617161625.GR137143@google.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --3MwIy2ne0vdjdPXF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon 2019-06-17 09:16:25, Matthias Kaehlcke wrote: > Hi Pavel, >=20 > On Sun, Jun 16, 2019 at 05:41:43PM +0200, Pavel Machek wrote: > > Hi! > >=20 > > > This reverts commit 288ceb85b505c19abe1895df068dda5ed20cf482. > > >=20 > > > According to the commit message the AUO B101EAN01 panel on minnie > > > requires a PWM delay of 200 ms, however this is not what the > > > datasheet says. The datasheet mentions a *max* delay of 200 ms > > > for T2 ("delay from LCDVDD to black video generation") and T3 > > > ("delay from LCDVDD to HPD high"), which aren't related to the > > > PWM. The backlight power sequence does not specify min/max > > > constraints for T15 (time from PWM on to BL enable) or T16 > > > (time from BL disable to PWM off). > > >=20 > > > Signed-off-by: Matthias Kaehlcke > > > --- > > > Enric, if you think I misinterpreted the datasheet please holler! > >=20 > > Was this tested? >=20 > I performed limited manually testing. >=20 > minnie ships with the Chrome OS 3.14 downstream, which doesn't include > this delay, to my knowledge there are no open display related bugs for > minnie. One could argue that a the configuration without the delay was > widely field tested >=20 > > Does patch being reverted actually break anything? >=20 > To my knowledge it doesn't really break anything, however there is a > short user perceptible delay between switching on the LCD and > switching on the backlight. It's not the end of the world, but if it's > not actually needed better avoid it. >=20 > > If so, cc stable? >=20 > I guess this is an edge case, were you could go either way. I'm fine > with respinning and cc-ing stable. Ok, if it is just a small delay, stable probably does not need to be involved. Thanks, Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --3MwIy2ne0vdjdPXF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAl0I0s0ACgkQMOfwapXb+vIDhwCgoXg7BeLdOOaZditUE387gqIo RsQAn0zNp/RpUuk4d69n9e90MTNfL8OK =uTEM -----END PGP SIGNATURE----- --3MwIy2ne0vdjdPXF--