This series adds a device tree overlay that enables the VGA output on Apalis iMX6, which is driven from a parallel RGB interface passing through a non-programmable video DAC.
The video DAC is a simple resistor network gated by an active-low data-enable signal. For the bridge to work properly, this series also changes the following in the dt-bindings and simple-bridge driver: - dt-bindings: Add the existing data-enable-active property from video-interfaces.yaml to the simple-bridge binding. The property is read from the bridge's input endpoint. This allows a dumb-vga-dac to specify a data-enable signal polarity. - simple-bridge: Read the data-enable-active property and fill out the bridge's input bus flags accordingly. The property is ignored if the bridge already has its own timings struct defined, to not interfere with its existing settings. This change depends on another patch, and should be applied after it: - https://lore.kernel.org/all/20261002-v1-simple-bridge-atomic-check-v1-1-ef5d8332b...@toradex.com/T/#u Adds the atomic_check function to the simple-bridge driver, which allows the data-enable bus flag to be propagated through the DRM pipeline. This is necessary for the VGA to work correctly on the Apalis iMX6. Changes in v2: - Introduce the data-enable-active property. - Describe the VGA bridge on the Apalis iMX6 as a dumb-vga-dac using the data-enable-active property to specify the DE signal polarity, instead of using a dedicated compatible. - Link to v1: https://lore.kernel.org/all/as-heYw7PKLPm3yH@SMW015318/T/#u Signed-off-by: Leonardo Costa <[email protected]> --- Leonardo Costa (3): dt-bindings: display: bridge: simple: Add data-enable-active to dumb-vga-dac drm/bridge: simple-bridge: Support data-enable-active endpoint property ARM: dts: imx6q-apalis: Add VGA overlay .../bindings/display/bridge/simple-bridge.yaml | 28 +++++++- arch/arm/boot/dts/nxp/imx/Makefile | 21 ++++++ .../boot/dts/nxp/imx/imx6q-apalis-eval-vga.dtso | 80 ++++++++++++++++++++++ drivers/gpu/drm/bridge/simple-bridge.c | 21 +++++- 4 files changed, 148 insertions(+), 2 deletions(-) --- base-commit: f33c2a109da4a527ed3103acb649a88e88cf368c change-id: 20261014-v2-apalis-imx6-enable-vga-450f5777a476 Best regards, -- Leonardo Costa <[email protected]>
