Hi Laurent, Did you have any time to look into this series? Thanks, Fab > From: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx> > Sent: 28 August 2019 19:37 > Subject: [PATCH v3 0/8] Add dual-LVDS panel support to EK874 > > 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 > (e.g. "panel-dual-lvds"), a new dt-binding document for it, and of course adding > support for the new compatible string to drivers/gpu/drm/panel/panel-lvds.c. > As a result, this series is missing (at least) a patch necessary to fully > document the new implementation within > Documentation/devicetree/bindings/display/panel/lvds.yaml > > Rob, do you have any suggestions? Do you think this idea works ok from a > documentation point of view? By the way, I don't really know what I am doing > with the yaml dt-bindings, I hope you won't be horrified by this series :-P > > I hope I was able to deliver the concept clearly, if not please just ask. > > Comments are very much appreciated. > > Thanks, > Fab > > Fabrizio Castro (8): > dt-bindings: display: Add bindings for LVDS bus-timings > dt-bindings: display: Add idk-2121wr binding > drm: Add bus timings helper > drm: rcar-du: lvds: Add dual-LVDS panels support > drm: bridge: thc63: Do not report input bus mode through bridge > timings > arm64: dts: renesas: Add EK874 board with idk-2121wr display support > [HACK] arm64: dts: renesas: draak: Enable LVDS > [HACK] arm64: dts: renesas: draak: Enable LVDS dual-link operation > > .../bindings/display/bus-timings/lvds.yaml | 38 +++++++ > .../display/panel/advantech,idk-2121wr.yaml | 90 ++++++++++++++++ > arch/arm64/boot/dts/renesas/Makefile | 3 +- > .../boot/dts/renesas/r8a774c0-ek874-idk-2121wr.dts | 116 +++++++++++++++++++++ > arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts | 21 +++- > arch/arm64/boot/dts/renesas/r8a77995-draak.dts | 26 +++-- > drivers/gpu/drm/Makefile | 3 +- > drivers/gpu/drm/bridge/thc63lvd1024.c | 9 +- > drivers/gpu/drm/drm_bus_timings.c | 97 +++++++++++++++++ > drivers/gpu/drm/rcar-du/rcar_lvds.c | 110 +++++++++++-------- > include/drm/drm_bridge.h | 8 -- > include/drm/drm_bus_timings.h | 21 ++++ > 12 files changed, 473 insertions(+), 69 deletions(-) > create mode 100644 Documentation/devicetree/bindings/display/bus-timings/lvds.yaml > create mode 100644 Documentation/devicetree/bindings/display/panel/advantech,idk-2121wr.yaml > create mode 100644 arch/arm64/boot/dts/renesas/r8a774c0-ek874-idk-2121wr.dts > create mode 100644 drivers/gpu/drm/drm_bus_timings.c > create mode 100644 include/drm/drm_bus_timings.h > > -- > 2.7.4
