Hotplug detection can be implemented either via HOTPLUG_CHG interrupt,
or the combination of PLUG and HPD_LOST interrupts.

For Rockchip platforms, configure HPD deglitch to 2ms and rely on
HOTPLUG_CHG interrupt for hotplug events, which is verified as the
optimal solution through engineering tests. Other platforms continue
using PLUG + HPD_LOST pair.

Adjust analogix_dp_config_interrupt() to apply platform-specific
interrupt masking and deglitch settings. Update threaded irq handler
to check corresponding interrupt flags according to platform type.

Signed-off-by: Damon Ding <[email protected]>
---
 .../gpu/drm/bridge/analogix/analogix_dp_core.c   |  9 +++++++--
 .../gpu/drm/bridge/analogix/analogix_dp_reg.c    | 16 +++++++++++++++-
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c 
b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 5af4150f0e7e..a292bc881b6b 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -719,10 +719,15 @@ static irqreturn_t analogix_dp_irq_thread(int irq, void 
*arg)
 {
        struct analogix_dp_device *dp = arg;
        u32 irq_type;
+       bool hpd_detected;
 
        irq_type = analogix_dp_get_irq_type(dp);
-       if (irq_type & DP_IRQ_TYPE_HP_CABLE_IN ||
-           irq_type & DP_IRQ_TYPE_HP_CABLE_OUT) {
+       if (!dp->hpd_gpiod && analogix_dp_is_rockchip(dp->plat_data->dev_type))
+               hpd_detected = irq_type & DP_IRQ_TYPE_HP_CHANGE;
+       else
+               hpd_detected = (irq_type & DP_IRQ_TYPE_HP_CABLE_IN) ||
+                              (irq_type & DP_IRQ_TYPE_HP_CABLE_OUT);
+       if (hpd_detected) {
                dev_dbg(dp->dev, "Detected cable status changed!\n");
                if (dp->drm_dev)
                        drm_helper_hpd_irq_event(dp->drm_dev);
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c 
b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
index 42463e18f392..981ce3810e90 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_reg.c
@@ -177,7 +177,21 @@ void analogix_dp_config_interrupt(struct 
analogix_dp_device *dp)
        writel(0, dp->reg_base + ANALOGIX_DP_COMMON_INT_MASK_2);
        writel(0, dp->reg_base + ANALOGIX_DP_COMMON_INT_MASK_3);
 
-       analogix_dp_unmute_hpd_interrupt(dp, HPD_IRQ);
+       if (analogix_dp_is_rockchip(dp->plat_data->dev_type)) {
+               /*
+                * Either HOTPLUG_CHG interrupt or PLUG + HPD_LOST interrupt
+                * pair can be used to implement hotplug detection.
+                *
+                * On Rockchip platforms, configuring HPD deglitch to 2ms and
+                * using HOTPLUG_CHG interrupt for hotplug detection is proven
+                * as a better solution via engineering verification.
+                */
+               writel(0x80, dp->reg_base + ANALOGIX_DP_HPD_DEGLITCH_L);
+               writel(0xbb, dp->reg_base + ANALOGIX_DP_HPD_DEGLITCH_H);
+               analogix_dp_unmute_hpd_interrupt(dp, DP_IRQ_TYPE_HP_CHANGE);
+       } else {
+               analogix_dp_unmute_hpd_interrupt(dp, HPD_IRQ);
+       }
 }
 
 void analogix_dp_mute_hpd_interrupt(struct analogix_dp_device *dp, u32 
irq_type)
-- 
2.34.1

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