From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933987AbcGKMhq (ORCPT ); Mon, 11 Jul 2016 08:37:46 -0400 Received: from mail-wm0-f42.google.com ([74.125.82.42]:36270 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933965AbcGKMho (ORCPT ); Mon, 11 Jul 2016 08:37:44 -0400 Date: Mon, 11 Jul 2016 14:37:37 +0200 From: Thierry Reding To: Eric Anholt Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, David Airlie Subject: Re: [PATCH] drm/panel: Remove the get_timings() function. Message-ID: <20160711123737.GC14709@ulmo.ba.sec> References: <1464808681-1970-1-git-send-email-eric@anholt.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ABTtc+pdwF7KHXCz" Content-Disposition: inline In-Reply-To: <1464808681-1970-1-git-send-email-eric@anholt.net> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --ABTtc+pdwF7KHXCz Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 01, 2016 at 12:18:01PM -0700, Eric Anholt wrote: > It appears to have no callers. >=20 > Signed-off-by: Eric Anholt > --- > drivers/gpu/drm/panel/panel-simple.c | 18 ------------------ > include/drm/drm_panel.h | 4 ---- > 2 files changed, 22 deletions(-) Looks like I never replied to this, though I remember at least making up the reply in my head. The reason why I'd like to keep this is that it's technically the right interface for display drivers to use. It was introduced in order to fix some of the short-comings of ->get_modes(), though it seems like there simply hasn't been a need so far for drivers to do this. The problem with ->get_modes() is that it gives you a fixed mode for most panels. However, a mode that works on one display controller does not necessarily work on another (typical reasons could be extra limits imposed on porches by the display controller). Timings are supposed to solve this by allowing the video timings to be specified in triplets of (minimum, maximum, typical) values for each of the parameters (much like the tables you see in panel datasheets) and make it possible for drivers to make up a valid mode from those ranges. This makes the panel more widely useful. At least that's the theory, but, like I said, in practice nobody seems to be needing this currently. Bottom line, I think we'll be needing this down the road eventually, so keeping it around will avoid unnecessary churn. Thierry --ABTtc+pdwF7KHXCz Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJXg5MQAAoJEN0jrNd/PrOhrUUQAJM+Oe7D2hD1BkD5ap076vxb KAWzzq3FlQwW7wbqNNKPjpFSl75FLyz8vAZ/nEu1rnwcNVeVcqsQvcEHI7VHO2jp 7OQCDDpNmM+rMNwTKpUtf5N4FHPRBl60DYxSZnqDl0osbtrD3XB4DmLsHs1vsrCb ow5bWEspcqQDZHFE0fdOS7qH8ZnL2lM3xN72oT75ZasWdBr4ZnUhTO3OrgA8qhsc qHf+5Q9ipKSbmxK5PnUrCqEh7LiFa3rtPml8wdoBMNeIJqTuYQvgHsmTclWbtBht IiNf/sGTcdRlLuZDX7SHVUUt62Ga4fa6g50aINZVxWSr09fna2k82wbKrfzvx6la MjVRsgl4XQWd296QbsG6cU/lGKd07uB1SmlZmwHbyfXoFWZLt3PpDX6eE+FpCxmi xfA4qayshg0kjh7eZN37rj2CHUQsHwFwJN4f7WBKpDUkkOtj1qc4fnQgd1i7dM6b 4hTSdKjmEGpFWYx45itkW8FP1zo/BnjDEYh5lTMN8eccnRyPXqN5mpL5Ynj+FIy7 aG+pk5SL5go0f8ZFq+aH83wrh9F7wl48FBJSCnGnug3w1uE1EQtYjoNdpAWQHP9c GxcoapvcpFrNYhO2MlCb2La4jNi+1v6zUOgWXzaSUCWieK54BmTuIcRCFaVeC0K5 U3ImilYqWxOvrIgJBPEo =L9no -----END PGP SIGNATURE----- --ABTtc+pdwF7KHXCz--