From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrzej Hajda Subject: Re: [PATCH v2 7/7] arm64: dts: allwinner: a64: enable ANX6345 bridge on Teres-I Date: Fri, 28 Jun 2019 12:39:32 +0200 Message-ID: References: <20190604122150.29D6468B05@newverein.lst.de> <20190604122308.98D4868B20@newverein.lst.de> <20190605101317.GA9345@lst.de> <20190605120237.ekmytfxcwbjaqy3x@flea> <20190607062802.m5wslx3imiqooq5a@flea> <20190607094030.GA12373@lst.de> <66707fcc-b48e-02d3-5ed7-6b7e77d53266@samsung.com> <20190612152022.c3cfhp4cauhzhfyr@flea> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190612152022.c3cfhp4cauhzhfyr@flea> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Maxime Ripard Cc: Torsten Duwe , Harald Geyer , Vasily Khoruzhick , Chen-Yu Tsai , Rob Herring , Mark Rutland , Thierry Reding , David Airlie , Daniel Vetter , Laurent Pinchart , Icenowy Zheng , Sean Paul , Greg Kroah-Hartman , Thomas Gleixner , dri-devel , devicetree , arm-linux , linux-kernel List-Id: devicetree@vger.kernel.org Hi Maxime, It seems I have missed your response. On 12.06.2019 17:20, Maxime Ripard wrote: >> I am not sure if I understand whole discussion here, but I also do not >> understand whole edp-connector thing. > The context is this one: > https://patchwork.freedesktop.org/patch/257352/?series=51182&rev=1 > https://patchwork.freedesktop.org/patch/283012/?series=56163&rev=1 > https://patchwork.freedesktop.org/patch/286468/?series=56776&rev=2 > > TL;DR: This bridge is being used on ARM laptops that can come with > different eDP panels. Some of these panels require a regulator to be > enabled for the panel to work, and this is obviously something that > should be in the DT. > > However, we can't really describe the panel itself, since the vendor > uses several of them and just relies on the eDP bus to do its job at > retrieving the EDIDs. A generic panel isn't really working either > since that would mean having a generic behaviour for all the panels > connected to that bus, which isn't there either. > > The connector allows to expose this nicely. As VESA presentation says[1] eDP is based on DP but is much more flexible, it is up to integrator (!!!) how the connection, power up/down, initialization sequence should be performed. Trying to cover every such case in edp-connector seems to me similar to panel-simple attempt failure. Moreover there is no such thing as physical standard eDP connector. Till now I though DT connector should describe physical connector on the device, now I am lost, are there some DT bindings guidelines about definition of a connector? Maybe instead of edp-connector one would introduce integrator's specific connector, for example with compatible "olimex,teres-edp-connector" which should follow edp abstract connector rules? This will be at least consistent with below presentation[1] - eDP requirements depends on integrator. Then if olimex has standard way of dealing with panels present in olimex/teres platforms the driver would then create drm_panel/drm_connector/drm_bridge(?) according to these rules, I guess. Anyway it still looks fishy for me :), maybe because I am not familiarized with details of these platforms. [1]: https://www.vesa.org/wp-content/uploads/2010/12/DisplayPort-DevCon-Presentation-eDP-Dec-2010-v3.pdf > >> According to VESA[1] eDP is "Internal display interface" - there is no >> external connector for eDP, the way it is connected is integrator's >> decision, but it is fixed - ie end user do not plug/unplug it. > I'm not sure if you mean DRM or DT connector here though. In DRM, > we're doing this all the time for panels. I'm literaly typing this > from a laptop that has a screen with an eDP connector. VESA describes only hardware, but since DT also describes hardware I guess it should be similar. Regards Andrzej > > Maxime > > -- > Maxime Ripard, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com