From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934134Ab1IOPut (ORCPT ); Thu, 15 Sep 2011 11:50:49 -0400 Received: from home.keithp.com ([63.227.221.253]:43259 "EHLO keithp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934067Ab1IOPus (ORCPT ); Thu, 15 Sep 2011 11:50:48 -0400 From: Keith Packard To: Tomi Valkeinen Cc: linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-dev@lists.linaro.org, "Clark\, Rob" , Archit Taneja Subject: Re: Proposal for a low-level Linux display framework In-Reply-To: <1316100594.23214.65.camel@deskari> References: <1316088425.11294.78.camel@lappyti> <1316100594.23214.65.camel@deskari> User-Agent: Notmuch/0.6.1-66-ga900dda (http://notmuchmail.org) Emacs/23.3.1 (i486-pc-linux-gnu) Date: Thu, 15 Sep 2011 10:50:32 -0500 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 Thu, 15 Sep 2011 18:29:54 +0300, Tomi Valkeinen = wrote: > 1) It's part of DRM, so it doesn't help fb or v4l2 drivers. Except if > the plan is to make DRM the core Linux display framework, upon which > everything else is built, and fb and v4l2 are changed to use DRM. I'd like to think we could make DRM the underlying display framework; it already exposes an fb interface, and with overlays, a bit more of the v4l2 stuff is done as well. Certainly eliminating three copies of mode setting infrastructure would be nice... > But even if it was done like that, I see that it's combining two > separate things: 1) the lower level HW control, and 2) the upper level > buffer management, policies and userspace interfaces. Those are split between the DRM layer and the underlying device driver, which provides both kernel (via fb) and user space interfaces. > 2) It's missing the panel driver part. This is rather important on > embedded systems, as the panels often are not "dummy" panels, but they > need things like custom initialization, sending commands to adjust > backlight, etc. We integrate the panel (and other video output) drivers into the device drivers. With desktop chips, they're not easily separable. None of the desktop output drivers are simple; things like DisplayPort require link training, and everyone needs EDID. We share some of that code in the DRM layer today, and it would be nice to share even more. We should figure out if the DRM interfaces are sufficient for your needs; they're pretty flexible at this point. Of course, backlight remains a mess in the desktop world; with many custom backlight drivers along with generic ACPI and then per-video-device drivers as well. =2D-=20 keith.packard@intel.com --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iD8DBQFOch7JQp8BWwlsTdMRAtirAJ9t/Y9/5k6NowfUcxMhQ+g5+tDvXgCdEXqG 6/s9sy8CHA1RKmF4tuwRwYk= =usgI -----END PGP SIGNATURE----- --=-=-=--