On Mon, Jul 01, 2019 at 02:27:51PM +0200, Andrzej Hajda wrote: > On 01.07.2019 11:58, Maxime Ripard wrote: > > 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). It doesn't have to be. > 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. Well, if there's a ribbon connector, then you have a physical connector, with the end user being able to connect / disconnect various displays. It might not be the case with actual products, but it's pretty common with SBCs to have that signal routed through a connector, and the user has several options to connect a display to it. The line really is blurred. > >> 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? Overlays are a solution, but I would advocate to always have the connector. Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
Attachment:
signature.asc
Description: PGP signature
