Hi Laurent, On Sun, May 12, 2019 at 12:06:52AM +0300, Laurent Pinchart wrote: > Hello everybody, > > This patch series implements support for LVDS dual-link mode in the > R-Car DU and R-Car LVDS encoder drivers, and well as in the thc63lvd1024 > LVDS decoder driver. > > LVDS dual-link is a mode of operation where two individual LVDS links > are operated together to carry even- and odd-numbered pixels separately. > This doubles the possible bandwidth of the video transmission. Both the > transmitter and the receiver need to support this mode of operation. > > The R-Car D3 and E3 SoCs include two independent LVDS encoders that can > be grouped together to operate in dual-link mode. When used separately, > the LVDS encoders are connected to two different CRTCs and transmit > independent video streams. When used in dual-link mode, the first LVDS > encoder is connected to the first CRTC, and split even- and odd-numbered > pixels. It transmits half of the pixels on its LVDS output, and sends > the other half to the second LVDS encoder for transmittion over the > second LVDS link. The second LVDS encoder thus operates under control of > the first one, and isn't connected directly to a CRTC. > > On the receiving side, the THC63LVD1024 LVDS-to-parallel bridge has two > LVDS inputs and two parallel outputs. It can operate in four different > modes: > > - Single-in, single-out: The first LVDS input receives the video stream, > and the bridge outputs it on the first parallel output. The second > LVDS input and the second parallel output are not used. > > - Single-in, dual-out: The first LVDS input receives the video stream, > and the bridge splits even- and odd-numbered pixels and outputs them > on the first and second parallel outputs. The second LVDS input is not > used. > > - Dual-in, single-out: The two LVDS inputs are used in dual-link mode, > and the bridge combines the even- and odd-numbered pixels and outputs > them on the first parallel output. The second parallel output is not > used. > > - Dual-in, dual-out: The two LVDS inputs are used in dual-link mode, > and the bridge outputs the even- and odd-numbered pixels on the first > parallel output. > > The operating mode is selected by two input pins of the bridge, which > are connected to DIP switches on the development boards I use. The mode > is thus fixed from a Linux point of view. > > Patch 01/10 adds a new dual_link boolen field to the drm_bridge_timings > structure to let bridges report their LVDS mode of operation. Patch > 02/10 clarifies the THC63LVD1024 DT bindings to document dual-link > operation, and patch 03/10 implements dual-link support in the > thc64lvd1024 bridge driver by setting the drm_bridge_timings dual_link > field according to the mode selected through DT. > > Patch 04/10 extends the R-Car LVDS DT bindings to specify the companion > LVDS encoder for dual-link operation. Patches 05/10 then performs a > small cleanup in the LVDS encoder driver. Patch 06/10 implements > dual-link support in the LVDS encoder driver, which involves retrieving > the operation mode from the LVDS receiver, locating the companion LVDS > encoder, and configuring both encoders when dual-link operation is > desired. The API towards the DU driver is also extended to report the > mode of operation. > > Patch 07/10 implements dual-link mode support in the DU driver. There is > no specific configuration to be performed there, as dual-link is fully > implemented in the LVDS encoder driver, but the DU driver has to skip > creation of the DRM encoder and connector related to the second LVDS > encoder when dual-link is used, as the second LVDS encoder operates as a > slave of the first one, transparently from a CRTC (and thus userspace) > perspective. > > Patch 08/10 specifies the companion LVDS encoder in the D3 and E3 DT > bindings. This by itself doesn't enable dual-link mode, the LVDS0 > encoder is still connected to the HDMI output through LVDS receiver, and > the LVDS1 encoder is not used. Patches 09/10 and 10/10, not intended to > be merged, enable dual-link operation for the D3 and E3 boards for > testing and require flipping DIP switches on the boards. > > The patches are based on top of my drm/du/next branch, and are available > for convenience at > > git://linuxtv.org/pinchartl/media.git drm/du/lvds/dual-link > > They have been tested successfully on the D3 Draak board. I expect them > to work on E3 as well, but I don't have access to an Ebisu board to test > this. I have now tested the series on E3 Ebisu board using kms-tests using the HDMI output and I confirm it works as expected. For the whole series: Tested-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx> Thanks j > > Laurent Pinchart (10): > drm: bridge: Add dual_link field to the drm_bridge_timings structure > dt-bindings: display: bridge: thc63lvd1024: Document dual-link > operation > drm: bridge: thc63: Report input bus mode through bridge timings > dt-bindings: display: renesas: lvds: Add renesas,companion property > drm: rcar-du: lvds: Remove LVDS double-enable checks > drm: rcar-du: lvds: Add support for dual-link mode > drm: rcar-du: Skip LVDS1 output on Gen3 when using dual-link LVDS mode > arm64: dts: renesas: r8a7799[05]: Point LVDS0 to its companion LVDS1 > [HACK] arm64: dts: renesas: draak: Enable LVDS dual-link operation > [HACK] arm64: dts: renesas: ebisu: Enable LVDS dual-link operation > > .../bindings/display/bridge/renesas,lvds.txt | 6 + > .../display/bridge/thine,thc63lvd1024.txt | 6 + > .../arm64/boot/dts/renesas/r8a77990-ebisu.dts | 21 ++- > arch/arm64/boot/dts/renesas/r8a77990.dtsi | 2 + > .../arm64/boot/dts/renesas/r8a77995-draak.dts | 21 ++- > arch/arm64/boot/dts/renesas/r8a77995.dtsi | 2 + > drivers/gpu/drm/bridge/thc63lvd1024.c | 54 ++++++-- > drivers/gpu/drm/rcar-du/rcar_du_encoder.c | 12 ++ > drivers/gpu/drm/rcar-du/rcar_du_kms.c | 2 +- > drivers/gpu/drm/rcar-du/rcar_lvds.c | 123 +++++++++++++----- > drivers/gpu/drm/rcar-du/rcar_lvds.h | 5 + > include/drm/drm_bridge.h | 8 ++ > 12 files changed, 214 insertions(+), 48 deletions(-) > > -- > Regards, > > Laurent Pinchart >
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