This series adds 'no-hpd' device tree property support to the Cadence MHDP8546 bridge driver for boards where the HPD line cannot be used for hotplug detection.
On TI J721S2 EVMs, the DP0 HPD resistor is DNI from factory, so the HPD signal is not physically connected to SoC pin AA24 by default. AA24 must still be in DP0_HPD mux mode for the MHDP firmware to operate. When 'no-hpd' is set, DRM_BRIDGE_OP_HPD is omitted and the framework falls back to polling .detect() every ~10 seconds. Presence is detected by reading DP_DPCD_REV (0x000) over AUX, with an early exit when the monitor is stably connected to avoid re-programming the stream each poll. Changes since v6: - Reverted back to dev_dbg instead of dev_err for the normal hpd case. - Picked up Acked-by from Krzysztof Kozlowski from v6 on the bindings patch. Link to v6: https://lore.kernel.org/all/[email protected]/ Rahul T R (2): dt-bindings: display: bridge: cdns,mhdp8546: Add no-hpd property to the cadence bridge drm: bridge: cdns-mhdp8546: Add no-hpd property .../display/bridge/cdns,mhdp8546.yaml | 11 +++ .../drm/bridge/cadence/cdns-mhdp8546-core.c | 69 +++++++++++++++++-- .../drm/bridge/cadence/cdns-mhdp8546-core.h | 1 + 3 files changed, 75 insertions(+), 6 deletions(-) -- 2.34.1
