[PATCH v1 0/7] Add HPD support for Rockchip Analogix DP

[Damon Ding <damon.ding@rock-chips.com>]

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,
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, which provides better stability than the PLUG + HPD_LOST
pair.

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>;
          };
      };
  };

Both configurations detect cable plug/unplug events correctly.

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: Extend mute/unmute helpers to accept an irq_type bitmask for
         per-event interrupt masking.
Patch 4: Extend clear_hotplug_interrupts() to accept an irq_type
         bitmask for per-event pending interrupt clearing.
Patch 5: Simplify analogix_dp_config_interrupt() by removing redundant
         local macros and leveraging the unmute helper.
Patch 6: Configure Rockchip platforms to use HOTPLUG_CHG interrupt with
         2ms HPD deglitch; other platforms keep PLUG + HPD_LOST pair.
Patch 7: Skip native HPD interrupt register operations for GPIO HPD
         mode, where hotplug is detected through an external GPIO.

Damon Ding (7):
  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: Extend mute/unmute HPD interrupts to accept
    irq bitmask
  drm/bridge: analogix_dp: Extend clear_hotplug_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/analogix_dp_core.c    |  46 ++++--
 .../drm/bridge/analogix/analogix_dp_core.h    |  10 +-
 .../gpu/drm/bridge/analogix/analogix_dp_reg.c | 146 ++++++++++++------
 3 files changed, 134 insertions(+), 68 deletions(-)

-- 
2.34.1