[PATCH v2 00/10] Add HPD support for Rockchip Analogix DP

This series improves the HPD (Hotplug Detect) interrupt handling in
the Analogix DP driver to enable reliable native HPD pin detection on
Rockchip platforms, and introduces platform-specific HPD detection
schemes with fine-grained interrupt control.

On Rockchip platforms, the Analogix DP native HPD pin IRQ requires the
DP controller to remain powered, clocked and initialized to generate
plug/unplug interrupts. The previous driver enabled/disabled IRQ during
bridge enable/disable, which left no HPD detection when the display
pipeline was inactive. Additionally, the interrupt mute/unmute/clear
routines operated on all HPD interrupt bits unconditionally, lacking
the granularity needed for per-event control.

The series reorganizes IRQ and pm_runtime management into bind/unbind,
adds IRQF_ONESHOT to eliminate read-modify-write races on interrupt
mask registers between hardirq and threaded handlers, converts the
interrupt type detection to a bitmask-based scheme for fine-grained
mute/unmute/clear operations, and configures Rockchip platforms to use
the HOTPLUG_CHG interrupt with a 2ms HPD deglitch setting for better
stability.

Patch  1: Move enable_irq()/disable_irq() to bind/unbind and hold a
          pm_runtime reference for Rockchip native HPD pin mode.
Patch  2: Convert analogix_dp_get_irq_type() to return a u32 bitmask
          instead of an enum, accumulating all pending interrupt flags.
Patch  3: Add IRQF_ONESHOT to prevent hardirq from preempting the
          threaded handler; remove redundant mute/unmute from runtime
          IRQ path; move status clearing before event handling.
Patch  4: Extend clear_hotplug_interrupts() to accept an irq_type
          bitmask for per-event pending interrupt clearing.
Patch  5: Extend mute/unmute helpers to accept an irq_type bitmask for
          init-time platform-specific interrupt mask configuration.
Patch  6: Simplify analogix_dp_config_interrupt() by removing redundant
          local macros and leveraging the unmute helper.
Patch  7: Configure Rockchip platforms to use HOTPLUG_CHG interrupt with
          2ms HPD deglitch; other platforms keep PLUG + HPD_LOST pair.
Patch  8: Skip native HPD interrupt register operations for GPIO HPD
          mode, where hotplug is detected through an external GPIO.
Patch  9: Restrict the forced connected-status shortcut to panel
          endpoints only, so DP connector bridges rely on HPD detection.
Patch 10: Handle HPD notification from downstream bridges (e.g.,
          display-connector with hpd-gpios) to short-circuit
          analogix_dp_detect_hpd() when connection is already confirmed.

Tested on RK3576 with both native HPD pin and GPIO HPD configurations.

Native HPD pin mode:

  &edp {
      status = "okay";
      pinctrl-names = "default";
      pinctrl-0 = <&edp_txm0_pins>;
  };

GPIO HPD mode:

  &edp {
      status = "okay";
      pinctrl-names = "default";
      pinctrl-0 = <&edp0_hpd>;
      hpd-gpios = <&gpio4 RK_PC1 GPIO_ACTIVE_HIGH>;
  };

  &pinctrl {
      edp {
          edp0_hpd: edp0-hpd {
              rockchip,pins = <4 RK_PC1 0 &pcfg_pull_none>;
          };
      };
  };

Display-connector mode (DP connector without HPD GPIO):

  &edp_out_conn {
      remote-endpoint = <&dp_con_in>;
  };

  dp-con {
      compatible = "dp-connector";
      label = "DP OUT";
      type = "full-size";

      port {
          dp_con_in: endpoint {
              remote-endpoint = <&edp_out_conn>;
          };
      };
  };

Display-connector mode (DP connector with HPD GPIO):

  dp-con {
      compatible = "dp-connector";
      label = "DP OUT";
      type = "full-size";
      pinctrl-0 = <&edp0_hpd>;
      pinctrl-names = "default";
      hpd-gpios = <&gpio4 RK_PC1 GPIO_ACTIVE_HIGH>;

      port {
          dp_con_in: endpoint {
              remote-endpoint = <&edp_out_conn>;
          };
      };
  };

All four configurations detect cable plug/unplug events correctly.

Damon Ding (10):
  drm/bridge: analogix_dp: Manage pm runtime and IRQ for native HPD pin
    detection
  drm/bridge: analogix_dp: Return bitmask from
    analogix_dp_get_irq_type()
  drm/bridge: analogix_dp: Add IRQF_ONESHOT and simplify IRQ handling
  drm/bridge: analogix_dp: Extend clear_hotplug_interrupts to accept IRQ
    bitmask
  drm/bridge: analogix_dp: Extend mute/unmute HPD interrupts to accept
    irq bitmask
  drm/bridge: analogix_dp: Simplify analogix_dp_config_interrupt()
  drm/bridge: analogix_dp: Use platform-specific HPD detection scheme
  drm/bridge: analogix_dp: Skip native HPD interrupt ops for GPIO HPD
  drm/bridge: analogix_dp: Restrict forced connected status only for
    panel endpoint
  drm/bridge: analogix_dp: Handle HPD notification from downstream
    bridge

 .../drm/bridge/analogix/analogix_dp_core.c    |  87 +++++++---
 .../drm/bridge/analogix/analogix_dp_core.h    |  12 +-
 .../gpu/drm/bridge/analogix/analogix_dp_reg.c | 152 ++++++++++++------
 3 files changed, 175 insertions(+), 76 deletions(-)

---

Changes in v2:
- Split IRQ enable/disable logic, handle native HPD pin and
  GPIO/force-HPD modes separately to avoid unbalanced enable_irq()
  calls.(Sashiko)
- Add separate patch for IRQF_ONESHOT to resolve interrupt mask issues
  triggered by interrupt preemption.(Sashiko)
- Update commit messages to align with newly added IRQF_ONESHOT related
  commit.
- Move ANALOGIX_DP_HPD_DEGLITCH_L/ANALOGIX_DP_HPD_DEGLITCH_H configs to
  analogix_dp_reset().
- Add new patch to restrict the forced connected-status shortcut to
  panel endpoints only, allowing DP connector bridges to rely on HPD
  detection. (Reported by Heiko Stuebner)
- Add new patch to handle HPD notification from downstream bridges
  (e.g., display-connector with hpd-gpios).

-- 
2.34.1