[PATCH v6 14/18] drm/bridge: analogix_dp: Move IRQ enable/disable to bind/unbind

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

Move enable_irq()/disable_irq() from bridge enable/disable handlers
into analogix_dp_bind()/analogix_dp_unbind(). This keeps the IRQ
active throughout the device lifecycle rather than only during display
activity, which is a prerequisite for supporting HPD detection while
the display pipeline is inactive.

Make the interrupt fully threaded and hold a runtime PM reference in
the threaded handler, so that no register is accessed while the
controller is runtime suspended.

Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Damon Ding <damon.ding@rock-chips.com>

---

Changes in v3:
- Move this patch after mute/unmute related modification and detail the
  commit msg.

Changes in v4:
- Add Tested-by tag.

Changes in v5:
- Use a pure threaded IRQ handler and hold a runtime PM reference in
  it, so that no MMIO happens on the unclocked controller after
  runtime suspend. (Sashiko)
- Add prep patches to call analogix_dp_unbind() when
  drm_bridge_connector_init() fails, so that the IRQ enabled across
  the bind lifetime gets properly disabled on bind failures. (Sashiko)

Changes in v6:
- Skip the runtime PM reference in the IRQ thread for the GPIO HPD
  mode, since it only reads the GPIO level. (Sashiko)
- Add Tested-by tag.
---
 .../drm/bridge/analogix/analogix_dp_core.c    | 40 +++++++++++--------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index b14a8aa12394..7f6346d45a01 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -700,24 +700,25 @@ static int analogix_dp_enable_scramble(struct analogix_dp_device *dp,
 	return ret < 0 ? ret : 0;
 }
 
-static irqreturn_t analogix_dp_hardirq(int irq, void *arg)
-{
-	struct analogix_dp_device *dp = arg;
-	irqreturn_t ret = IRQ_NONE;
-	u32 irq_type;
-
-	irq_type = analogix_dp_get_irq_type(dp);
-	if (irq_type)
-		ret = IRQ_WAKE_THREAD;
-
-	return ret;
-}
-
 static irqreturn_t analogix_dp_irq_thread(int irq, void *arg)
 {
 	struct analogix_dp_device *dp = arg;
 	u32 irq_type;
 	bool hpd_detected;
+	int ret;
+
+	/*
+	 * The device may have been runtime suspended since the interrupt was
+	 * raised. Hold a runtime PM reference before touching the registers,
+	 * as the controller clocks are only guaranteed to be enabled while
+	 * the device is runtime PM active. The GPIO HPD mode needs no such
+	 * reference, since it only reads the GPIO level.
+	 */
+	if (!dp->hpd_gpiod) {
+		ret = pm_runtime_resume_and_get(dp->dev);
+		if (ret)
+			return IRQ_HANDLED;
+	}
 
 	irq_type = analogix_dp_get_irq_type(dp);
 	if (!dp->hpd_gpiod && irq_type)
@@ -734,6 +735,11 @@ static irqreturn_t analogix_dp_irq_thread(int irq, void *arg)
 			drm_helper_hpd_irq_event(dp->drm_dev);
 	}
 
+	if (!dp->hpd_gpiod) {
+		pm_runtime_mark_last_busy(dp->dev);
+		pm_runtime_put_autosuspend(dp->dev);
+	}
+
 	return IRQ_HANDLED;
 }
 
@@ -1056,7 +1062,6 @@ static int analogix_dp_set_bridge(struct analogix_dp_device *dp)
 		goto out_dp_init;
 	}
 
-	enable_irq(dp->irq);
 	return 0;
 
 out_dp_init:
@@ -1198,8 +1203,6 @@ static void analogix_dp_bridge_disable(struct drm_bridge *bridge)
 	if (dp->dpms_mode != DRM_MODE_DPMS_ON)
 		return;
 
-	disable_irq(dp->irq);
-
 	analogix_dp_set_analog_power_down(dp, POWER_ALL, 1);
 
 	pm_runtime_put_sync(dp->dev);
@@ -1527,7 +1530,7 @@ analogix_dp_probe(struct device *dev, struct analogix_dp_plat_data *plat_data)
 	}
 
 	ret = devm_request_threaded_irq(&pdev->dev, dp->irq,
-					analogix_dp_hardirq,
+					NULL,
 					analogix_dp_irq_thread,
 					irq_flags, "analogix-dp", dp);
 	if (ret)
@@ -1613,6 +1616,8 @@ int analogix_dp_bind(struct analogix_dp_device *dp, struct drm_device *drm_dev)
 		goto err_unregister_aux;
 	}
 
+	enable_irq(dp->irq);
+
 	return 0;
 
 err_unregister_aux:
@@ -1624,6 +1629,7 @@ EXPORT_SYMBOL_GPL(analogix_dp_bind);
 
 void analogix_dp_unbind(struct analogix_dp_device *dp)
 {
+	disable_irq(dp->irq);
 	drm_dp_aux_unregister(&dp->aux);
 }
 EXPORT_SYMBOL_GPL(analogix_dp_unbind);
-- 
2.34.1