rockchip64: fix clang -Wincompatible-pointer-types-discards-qualifiers in carried patches

[iav]

Description

Two carried rockchip64 kernel patches assign a const pointer to a non-const one, which clang rejects under -Werror,-Wincompatible-pointer-types-discards-qualifiers:

• general-add-panel-simple-dsi.patch: of_get_drm_display_mode(..., &p->desc->bus_format, ...) — desc is const.
• rk3399-usbc-notify-typec-dp-hpd-state-through-extcon.patch: const struct device *dev = &dp->alt->dev; is passed to extcon_get_edev_by_phandle(), which takes a non-const struct device *.

Fix:

• panel-simple-dsi: cast (u32 *)&p->desc->bus_format — the pointed-to memory is writable (a devm_kmemdup copy), only the pointer type is const. Replicated to rockchip64-{6.6,6.12,6.18,7.1} (7.2 has the patch .disabled).
• displayport extcon: drop the needless const on the local dev (6.18 only; 6.6/6.12 don't carry this patch, 7.1/7.2 already use the non-const form).

Behaviour-preserving; GCC was already silent on both.

How Has This Been Tested?

rockchip64 clang build (armsom-sige5) — both files compile clean under clang.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My changes generate no new warnings

Summary by CodeRabbit

• New Features
  • Added support for simple MIPI-DSI DRM display panels, with device-tree driven initialization/exit command sequences.
  • Added device-tree configurable panel power, reset, and enable GPIO handling, plus automatic mode/physical size, preferred mode selection, orientation, and timing reporting.
• Bug Fixes
  • Improved DisplayPort HPD hotplug state propagation to external hotplug signaling for more reliable display event updates.
  • Enhanced display mode probing behavior to set preferred mode and physical dimensions more consistently.

[coderabbitai]

📝 Walkthrough

Walkthrough

Updates repeated kernel patch files to cast bus_format in of_get_drm_display_mode(), and adds extcon-based DisplayPort HPD propagation in the rockchip64-6.18 altmode patch.

Changes

bus_format cast fix

Layer / File(s)	Summary
bus_format pointer cast across kernel versions patch/kernel/archive/rockchip64-6.6/general-add-panel-simple-dsi.patch, patch/kernel/archive/rockchip64-6.12/general-add-panel-simple-dsi.patch, patch/kernel/archive/rockchip64-6.18/general-add-panel-simple-dsi.patch, patch/kernel/archive/rockchip64-7.1/general-add-panel-simple-dsi.patch	Each patch updates the of_get_drm_display_mode() call in panel_simple_get_modes() to pass bus_format with an explicit (u32 *) cast.

DisplayPort HPD extcon notification

Layer / File(s)	Summary
Extcon discovery and HPD update helper patch/kernel/archive/rockchip64-6.18/rk3399-usbc-notify-typec-dp-hpd-state-through-extcon.patch	Adds extcon/of headers and dp_altmode_update_extcon_hpd_status(), which skips redundant updates, locates an extcon device via the device/OF node chain, checks EXTCON_DISP_HPD support, and sets/syncs EXTCON_PROP_DISP_HPD.
Wiring HPD helper into status update and disconnect paths patch/kernel/archive/rockchip64-6.18/rk3399-usbc-notify-typec-dp-hpd-state-through-extcon.patch	Calls the new helper from dp_altmode_status_update() when HPD changes, after the connector OOB hotplug event, and from dp_altmode_vdm() before clearing dp->hpd.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

sequenceDiagram
  participant dp_altmode_status_update as dp_altmode_status_update
  participant dp_altmode_update_extcon_hpd_status as dp_altmode_update_extcon_hpd_status
  participant OF device chain as OF device chain
  participant extcon device as extcon device

  dp_altmode_status_update->>dp_altmode_update_extcon_hpd_status: update HPD state
  dp_altmode_update_extcon_hpd_status->>dp_altmode_update_extcon_hpd_status: check cached dp->hpd
  dp_altmode_update_extcon_hpd_status->>OF device chain: walk parent OF nodes
  OF device chain-->>dp_altmode_update_extcon_hpd_status: extcon node / phandle
  dp_altmode_update_extcon_hpd_status->>extcon device: check EXTCON_DISP_HPD capability
  dp_altmode_update_extcon_hpd_status->>extcon device: set EXTCON_PROP_DISP_HPD and sync

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Suggested reviewers: ColorfulRhino, JohnTheCoolingFan, TheSnowfield, Tonymac32, SuperKali, chainsx, pyavitz, igorpecovnik

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: fixing a clang qualifier-discard warning in carried rockchip64 patches.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

✅ This PR has been reviewed and approved — all set for merge!