On 01.07.2019 11:58, Maxime Ripard wrote: > Hi! > > On Fri, Jun 28, 2019 at 12:39:32PM +0200, Andrzej Hajda wrote: >> 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? > This might be semantics but I guess we're in some kind of grey area? > > Like, for eDP, if it's soldered I guess we could say that there's no > connector. But what happens if for some other board, that signal is > routed through a ribbon? > > You could argue that there's no physical connector in both cases, or > that there's one in both, or one for the ribbon and no connector for > the one soldered in. This is not about ribbon vs soldering. It is about usage: this connection is static across the whole life of the device (except exceptional things: repair, non-standard usage, etc). And "the real connector" is (at least for me) something where end-user can connect/disconnect different things: USB, HDMI, ethernet, etc. And obviously to be functional it should be somehow standardized. So even if there could be some grey area, I do not see it here. > >> 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. > That makes sense yes And what if some panel can be used with this pseudo-connecter and in some different hw directly? Code duplication? DT overlays? Regards Andrzej > > Maxime > > -- > Maxime Ripard, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com
