Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932766AbbHYOXy (ORCPT ); Tue, 25 Aug 2015 10:23:54 -0400 Received: from regular1.263xmail.com ([211.150.99.138]:44970 "EHLO regular1.263xmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932594AbbHYOXu (ORCPT ); Tue, 25 Aug 2015 10:23:50 -0400 X-263anti-spam: KSV:0; X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-KSVirus-check: 0 X-ABS-CHECKED: 4 X-ADDR-CHECKED: 0 X-RL-SENDER: ykk@rock-chips.com X-FST-TO: andy.yan@rock-chips.com X-SENDER-IP: 220.249.180.47 X-LOGIN-NAME: ykk@rock-chips.com X-UNIQUE-TAG: X-ATTACHMENT-NUM: 0 X-DNS-TYPE: 0 Subject: Re: [PATCH v3 06/14] Documentation: drm/bridge: add document for analogix_dp To: Thierry Reding References: <1439995728-18046-1-git-send-email-ykk@rock-chips.com> <1439995834-18363-1-git-send-email-ykk@rock-chips.com> <20150825091534.GB14034@ulmo.nvidia.com> <55DC7211.9080601@rock-chips.com> <20150825141642.GA3820@ulmo.nvidia.com> Cc: Rob Herring , Heiko Stuebner , Jingoo Han , Fabio Estevam , Inki Dae , Joe Perches , Russell King , Sean Paul , Takashi Iwai , dri-devel , Andrzej Hajda , Gustavo Padovan , "linux-samsung-soc@vger.kernel.org" , Vincent Palatin , linux-rockchip@lists.infradead.org, Kishon Vijay Abraham I , David Airlie , "devicetree@vger.kernel.org" , Pawel Moll , Ian Campbell , Doug Anderson , Rob Herring , "linux-arm-kernel@lists.infradead.org" , Mark Yao , "linux-kernel@vger.kernel.org" , Kyungmin Park , Daniel Kurtz , Philipp Zabel , Kumar Gala , Ajay kumar , Andy Yan From: Yakir Yang Message-ID: <55DC7A5C.1010108@rock-chips.com> Date: Tue, 25 Aug 2015 22:23:24 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <20150825141642.GA3820@ulmo.nvidia.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2759 Lines: 68 Hi Thierry, 在 2015/8/25 22:16, Thierry Reding 写道: > On Tue, Aug 25, 2015 at 09:48:01PM +0800, Yakir Yang wrote: >> Hi Thierry & Rob, >> >> 在 2015/8/25 21:27, Rob Herring 写道: >>> On Tue, Aug 25, 2015 at 4:15 AM, Thierry Reding wrote: >>>> On Sun, Aug 23, 2015 at 06:23:14PM -0500, Rob Herring wrote: >>>>> On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang wrote: >>>> [...] >>>>>> + -analogix,link-rate: >>>>>> + max link rate supported by the eDP controller. >>>>>> + LINK_RATE_1_62GBPS = 0x6, LINK_RATE_2_70GBPS = 0x0A, >>>>>> + LINK_RATE_5_40GBPS = 0x14 >>>>> Same here. I'd rather see something like "link-rate-mbps" and use the >>>>> actual rate. >>>> There is no need whatsoever to hard-code this in DT. (e)DP provides the >>>> means to detect what rate the link supports and the specification >>>> provides guidance on how to select an appropriate one. >>> Good, even better. >> I do think we still need keep this DT prop yet. >> >> I think drm_dp_help.c could get the "panel" max link-rate and lane-count, >> but it's not enough, we still need knew the "eDP controller" max link-rate >> and lane-count. >> >> Let me show the exact example that happened in my side. When I connect >> my board to my 2K DP-1.2 TV. Analogix dp driver would get the max link-rate >> from dpcd, and the max link-rate is 5.4Gbps. So if I just set eDP controller >> link-rate >> to 5.4Gbps, the DP TV just broken, do not light up normally. >> >> This reason why TV broken is the max link-rate which support by RK3288 eDP >> controller is 2.7Gbps. Here are the exact words that RK3288 eDP TRM said: >> >> *Compliant with DisplayPortTM Specification, Version 1.2. >> Compliant with eDPTM Specification, Version 1.3. >> HDCP v1.3 amendment for DisplayPortTM Revision 1.0. >> Main link containing 4 physical lanes of 2.7/1.62 Gbps/lane >> * >> ** >> >> >> Beside I haven't found there are some registers would indicate the eDP >> controller >> max link-rate and lane-count, so this is why I still instance that we need >> this DT >> prop to indicata "Max rate controller support". >> >> So, I wish you could agree with me on this point. > Your driver should know what link rates it supports and restrict itself > to use those. This is implied by the compatible string and doesn't need > to be duplicated into device tree. Oh, yeah, good idea :-D Thanks for your point out. - Yakir > Thierry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/