From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756258Ab1I3RuQ (ORCPT ); Fri, 30 Sep 2011 13:50:16 -0400 Received: from home.keithp.com ([63.227.221.253]:47584 "EHLO keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751753Ab1I3RuO (ORCPT ); Fri, 30 Sep 2011 13:50:14 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "Cc" From: Keith Packard To: Daniel Vetter Cc: Dave Airlie , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: Re: [PATCH 03/21] drm/i915: Remove extra 300ms delay during eDP mode setting In-Reply-To: <20110930162728.GC2859@phenom.ffwll.local> References: <20110923085243.6e4b7b4c@jbarnes-x220> <1317344993-24945-1-git-send-email-keithp@keithp.com> <1317344993-24945-4-git-send-email-keithp@keithp.com> <20110930162728.GC2859@phenom.ffwll.local> User-Agent: Notmuch/0.6.1-66-ga900dda (http://notmuchmail.org) Emacs/23.3.1 (i486-pc-linux-gnu) cc: "Barnes, Jesse" Date: Fri, 30 Sep 2011 10:50:10 -0700 Message-ID: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Transfer-Encoding: quoted-printable On Fri, 30 Sep 2011 18:27:28 +0200, Daniel Vetter wrote: > Can you elaborate a bit why this is no longer needed? Jesse seems to have > introduced this spefically for edp panels in d209848d61794968. If this > becomes rendundant due to your panel power sequencing fixes, maybe move it > down the series? The only reason for this delay is to avoid some potential noise on the screen during mode setting, all of the power sequencing delays are already correctly managed by the driver. As far as I can tell, we're trading off the small potential for noise on the screen with an extra 300ms delay at boot time. In the eDP spec, there's a delay listed (T8) between the start of video data and turning on the backlight. There are no values presented and the instructions are simply that the source is supposed to wait until the display is stable. I'm not sure how we'd ever know that the display is stable. =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iD8DBQFOhgFSQp8BWwlsTdMRApAaAKChyKoHWE5gMA6dh9smAw68lxSv8ACfU2/I QOOqAUEfP44HLPlLchedVaQ= =ZqzK -----END PGP SIGNATURE----- --=-=-=--