drm/tilcdc: Convert legacy panel binding via DT overlay at boot time

To maintain backward compatibility while removing the deprecated
tilcdc_panel driver, add a tilcdc_panel_legacy subdriver that converts
the legacy "ti,tilcdc,panel" devicetree binding to the standard
panel-dpi binding at early boot.

The conversion uses an embedded device tree overlay that is applied and
modified during subsys_initcall. The process:

- Apply embedded overlay to create a tilcdc-panel-dpi node with
  port/endpoint connections to the LCDC
- Copy all properties from the legacy panel node to the new
  tilcdc-panel-dpi node
- Copy display-timings from the legacy panel
- Convert legacy panel-info properties (invert-pxl-clk, sync-edge) to
  standard display timing properties (pixelclk-active, syncclk-active)
- Disable the legacy panel by removing its compatible property to
  prevent the deprecated driver from binding

The result is a standard tilcdc-panel-dpi node with proper endpoints and
timing properties, allowing the DRM panel infrastructure to work with
legacy devicetrees without modification.

Other legacy panel-info properties are not migrated as they consistently
use default values across all mainline devicetrees and can be hardcoded
in the tilcdc driver.

This feature is optional via CONFIG_DRM_TILCDC_PANEL_LEGACY and should
only be enabled for systems with legacy devicetrees containing
"ti,tilcdc,panel" nodes.

Suggested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://lore.kernel.org/all/1d9a9269-bfda-4d43-938b-2df6b82b9369@ideasonboard.com/
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Kory Maincent (TI.com) <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20260123-feature_tilcdc-v5-5-5a44d2aa3f6f@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

0 files changed, 0 insertions, 0 deletions