Hi Rob, Thank you for your feedback! > From: Rob Herring <robh+dt@xxxxxxxxxx> > Sent: 29 August 2019 16:27 > To: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx> > Subject: Re: [PATCH v3 0/8] Add dual-LVDS panel support to EK874 > > On Wed, Aug 28, 2019 at 1:36 PM Fabrizio Castro > <fabrizio.castro@xxxxxxxxxxxxxx> wrote: > > > > Dear All, > > > > this series adds support for dual-LVDS panel IDK-2121WR > > from Advantech: > > https://buy.advantech.eu/Displays/Embedded-LCD-Kits-High-Brightness/model-IDK-2121WR-K2FHA2E.htm > > > > V3 approaches the problem in a completely different way, we now > > have two new properties to mark the ports in the DT as receiving > > even pixels and odd pixels: dual-lvds-even-pixels and dual-lvds-odd-pixels, > > which means device drivers should not use bridge specific or panel > > specific dual_link flags. Also, in this case the DT describes the > > connection fully. > > > > In order for the solution to be generic, I have exported a new helper > > (drm_of_lvds_get_dual_link_configuration) to walk the device tree, > > and figure out if the connection is dual-LVDS. The same helper gives > > information about the configuration of the connection. If Px is connected > > to a port expecting even pixels and Py is connected to a port expecting > > odd pixels, then the helper returns DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS > > (like in the example below), otherwise it returns > > DRM_LVDS_DUAL_LINK_ODD_EVEN_PIXELS. > > > > > > -------- dual-lvds-even-pixels -------- > > | |---- ----| | > > | | Px |---------------------->| Pn | | > > | |---- ----| | > > | SOURCE | dual-lvds-odd-pixels | SINK | > > | |---- ----| | > > | | Py |---------------------->| Pm | | > > | |---- ----| | > > -------- -------- > > > > The device driver for the encoder then will work out if with the current > > wiring the pixels need swapping or not. > > > > The same solution works for both panels and bridges. > > > > Since the DT describes the connection fully, driver > > drivers/gpu/drm/panel/panel-lvds.c works out-of-the-box, no changes > > required, however, this implementation opens up a problem with the > > dt-bindings. > > Driver drivers/gpu/drm/panel/panel-lvds.c can still be pleased by > > a port node, but also by a ports node. > > I have created Documentation/devicetree/bindings/display/bus-timings/lvds.yaml > > with the idea of including it from panels and bridges dt-bindings > > supporting dual-LVDS (and of course the dt-bindings for the specific > > devices should say which port should be marked as what), but file > > Documentation/devicetree/bindings/display/panel/lvds.yaml formally > > requires property "port", while with this implementation it should require > > OneOf "port" and "ports", and unfortunately I can't seem to find a neat way > > aroud that, other than creating a new compatible string > > Just add 'ports' and drop 'port' from being required in the common > binding. Then it is up to the panel specific bindings to define which > one is required. Or we just leave it to allow either form which the > graph code can handle. > > We could have this in the common binding: > > oneOf: > - required: [ports] > - required: [port] Thank you for Rob for looking into this. I will wait for a feedback from Laurent on the code before sending out v4. Thanks, Fab > > Rob
