kernel: M4 VOP display driver ported to 6.18 — binds on hardware (connector WIP)

The RV1106 VOP is the RV-series "lite" VOP (rockchip,rv1106-vop, VOP_VERSION 2.0xc),
mainline's VOP1 driver. Its sibling rv1126 is already in 6.18, so rv1106_vop reuses
rv1126's register sub-structs + VOP_FEATURE_INTERNAL_RGB + the smaller raster.

Verified on warden-c8a3: with the driver delta + DT (vop enabled with named
"ahb"/"dclk" resets, vop_out repointed to a panel-dpi 720x720 node, pwm-backlight
on pwm1), the VOP BINDS and DRM initialises (/dev/dri/card0), and the PWM backlight
comes up. The register data / version / feature / resets are validated.

Open: /sys/class/drm/card0 has no connector yet — rockchip_rgb_init isn't producing
one ("Cannot find any crtc"). Last mile of M4; needs a debug print in rgb_init + the
panel bus_format, and the pixels must be verified on the physical panel (can't be
checked over serial/ssh). Full recipe + next steps in display/README.md.

Also batch-2 config: GPIO_SYSFS, PWM_ROCKCHIP, crypto (aes/ccm/ctr/arc4), CFG80211,
DRM_ROCKCHIP/ROCKCHIP_VOP all =y; PSCI-style SMC removed via the psci-node deletion.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017wB8KB3MMQztRDXCMCkPrf

kernel/rv1106-enablement/display/README.md

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+# M4 — display (VOP) port to 6.18
+
+The RV1106 VOP is the older RV-series "lite" VOP (`rockchip,rv1106-vop`, VOP_VERSION
+2.0xc), driven by mainline's `rockchip_drm_vop.c` (VOP1), **not** VOP2. Its sibling
+**rv1126** is already in mainline 6.18, so the register data is a small reuse — like
+the clk/pinctrl ports.
+
+## The driver delta (`rockchip_vop_reg.c`)
+
+`rv1106_vop_data.c.frag` — add this `vop_data` (reuses rv1126's common/modeset/
+output/misc/intr/win sub-structs; only the version, the smaller 1280² raster, and
+the **`VOP_FEATURE_INTERNAL_RGB` feature** differ), plus the match entry:
+
+```c
+{ .compatible = "rockchip,rv1106-vop", .data = &rv1106_vop },
+```
+
+`VOP_FEATURE_INTERNAL_RGB` is essential — it is what makes `vop_bind` call
+`rockchip_rgb_init()` for the parallel-RGB output (rv1126 routes through MIPI and
+omits it).
+
+## The DT (in `../dts/rv1106-warden.dts`)
+
+- `&vop` enabled + **named resets** `resets = <&cru SRST_H_VOP>, <&cru SRST_D_VOP>;
+  reset-names = "ahb", "dclk";` — the mainline driver requires these (the vendor
+  node omits them; without them: `vop_bind: failed to get ahb reset`).
+- `&vop_out_rgb` repointed straight to the panel (mainline has no separate rgb
+  node — `rockchip_rgb_init` is a helper the VOP calls).
+- `panel` (`panel-dpi`, 720×720, 30 MHz) + `pwm-backlight` on `&pwm1`.
+
+## Verified on warden-c8a3 (2026-08-24)
+
+`CONFIG_DRM_ROCKCHIP=y` + `CONFIG_ROCKCHIP_VOP=y`. On hardware:
+```
+rockchip-drm display-subsystem: bound ff990000.vop
+[drm] Initialized rockchip 1.0.0 for display-subsystem on minor 0
+```
+`/dev/dri/card0` is present and the **PWM backlight is up** (`/sys/class/backlight`,
+brightness settable). **The VOP driver port is validated** — the register data,
+version, feature, and resets are right.
+
+## Open (needs on-panel eyes + a little more debug)
+
+`/sys/class/drm/card0-*` has **no connector yet** — `rockchip_rgb_init` isn't
+producing one (log: `Cannot find any crtc or sizes`), despite INTERNAL_RGB set and
+a clean vop→panel of_graph. Likely a panel-probe-order / `drm_of_find_panel_or_bridge`
+detail. This is the last mile of M4 and, unlike the driver bind, needs the panel
+physically observed (pixels can't be verified over serial/ssh). To pin it down: a
+debug print in `rockchip_rgb_init` (child_count / find-panel ret), and set the panel
+bus_format to `MEDIA_BUS_FMT_RGB666_1X18` (a small `panel_dpi_probe` addition, since
+mainline panel-dpi doesn't read bus-format from DT).

kernel/rv1106-enablement/display/rv1106_vop_data.c.frag

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+ * RV1106 VOP: the same RV-series "lite" VOP as rv1126 (VOP_VERSION 2.0xc vs
+ * 2.0xb), so it reuses rv1126's register sub-structs. Only the version and the
+ * smaller max raster differ. Ported for the WardenOS 86-Panel (720x720 RGB).
+ */
+static const struct vop_data rv1106_vop = {
+	.version = VOP_VERSION(2, 0xc),
+	.feature = VOP_FEATURE_INTERNAL_RGB,	/* RV1106 drives a parallel-RGB panel */
+	.intr = &px30_intr,
+	.common = &rv1126_common,
+	.modeset = &rv1126_modeset,
+	.output = &rv1126_output,
+	.misc = &rv1126_misc,
+	.win = rv1126_vop_win_data,
+	.win_size = ARRAY_SIZE(rv1126_vop_win_data),
+	.max_output = { 1280, 1280 },
+	.lut_size = 1024,
+};