From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751128AbcIGEvJ (ORCPT ); Wed, 7 Sep 2016 00:51:09 -0400 Received: from smtp.csie.ntu.edu.tw ([140.112.30.61]:47470 "EHLO smtp.csie.ntu.edu.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750792AbcIGEvH (ORCPT ); Wed, 7 Sep 2016 00:51:07 -0400 MIME-Version: 1.0 In-Reply-To: <20160906185452.GI9040@lukather> References: <20160901153204.11217-1-maxime.ripard@free-electrons.com> <18951472779805@web6g.yandex.ru> <20160902190605.GF6313@lukather> <20160905203707.GF8596@lukather> <20160906185452.GI9040@lukather> From: Chen-Yu Tsai Date: Wed, 7 Sep 2016 12:49:58 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 0/7] drm/sun4i: Introduce A33 display driver To: Maxime Ripard Cc: Chen-Yu Tsai , Icenowy Zheng , Daniel Vetter , David Airlie , Thierry Reding , Thomas Petazzoni , "linux-kernel@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linux-sunxi@googlegroups.com" , Rob Herring , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 7, 2016 at 2:54 AM, Maxime Ripard wrote: > On Tue, Sep 06, 2016 at 10:50:09AM +0800, Chen-Yu Tsai wrote: >> >> The implementation might be along the lines of >> >> >> >> 1. having multiple output ports, each for a different interface type. >> >> (Some platforms go this route) >> >> >> >> Or >> >> >> >> 2. having a DT property describe what the output interface is. >> >> >> >> The RGB/TCON driver would then setup the registers accordingly. >> > >> > Hmmm, yeah, we would need to adjust the bindings too... >> > >> > I guess I'd prefer 1), but that would also be the most invasive >> > solution. I'm not sure how the DT maintainers feel about that. >> >> I wonder if the TCON could use its 2 channels simultaneously? > > No, it's mutually exclusive. I don't see how though. Are you referring to the IO_Map_Sel bit? I assume that only controls the external output pins though. >> Like output to one LCD, then mirror through HDMI/VGA? >> The first option would be able to cover this better? > > Even if it wasn't exclusive, that wouldn't be possible > unfortunately. Or rather, this would be possible if the LCD and the > HDMI screen had the same timings, which is very unlikely. What about an LCD-VGA bridge + HDMI in mirror mode on sun6i? That should work. >> And you still need to add outgoing endpoints for the HDMI block. > > Indeed. On second thought, this particular one shouldn't affect the binding. > >> In addition we'll have to rework the TV encoder binding as well. >> >> The 2 TV encoders (on the A20) each have four DACs, which map >> onto 4 external pins. The address space includes a not so easy >> to use mux. More importantly, the binding needs to specify which >> pin is used for what signal (RGB, YUV, S/Video, composite). >> There seems to be an implicit rule that 1 pin is always used >> for composite, and the 3 others RGB, though. > > I'm not sure why we would need to rework this one though. We have no > way to detect whether the screen is connected or not on either > connectors, and we can't have both output running at the same time for > the same reason than mention above. I would like to add connector nodes. At least we can specify stuff like what DAC outputs are used for which connector, what type of connector, and a ddc bus for VGA connectors. I haven't worked out the details though. Regards ChenYu