[PATCH v8 26/29] drm/msm/dp: wake threaded handler for HPD IRQs

[Yongxing Mou <yongxing.mou@oss.qualcomm.com>]

The primary IRQ handler latches HPD status for the threaded handler
before servicing DP controller interrupts.

When an HPD interrupt was pending, the handler set its return value to
IRQ_WAKE_THREAD and then ORed it with msm_dp_ctrl_isr()'s return value.
If the controller ISR returned IRQ_HANDLED, the primary handler returned
IRQ_HANDLED | IRQ_WAKE_THREAD instead.

The IRQ core wakes an action's thread only when its primary handler
returns IRQ_WAKE_THREAD exactly. In that case, the HPD status was latched
for the threaded handler, but the handler itself was not woken.

Return IRQ_WAKE_THREAD directly whenever an unmasked HPD interrupt is
pending, after servicing controller interrupts in hardirq context, while
retaining the existing IRQ_HANDLED fallback for non-HPD interrupts.

Also report STATUS2 interrupts as handled. msm_dp_ctrl_get_interrupt()
acknowledges every pending STATUS2 source, including sources that need no
additional action, so they must not be reported as IRQ_NONE.

Fixes: 5043357e75ba ("drm/msm/dp: rework HPD handling")
Cc: stable@vger.kernel.org # v7.2+
Signed-off-by: Yongxing Mou <yongxing.mou@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c    | 3 +++
 drivers/gpu/drm/msm/dp/dp_display.c | 7 ++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index 82fb3ae750f4..5623693d9242 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -3018,6 +3018,9 @@ irqreturn_t msm_dp_ctrl_isr(struct msm_dp_ctrl *msm_dp_ctrl,
 	}
 
 	isr = msm_dp_ctrl_get_interrupt(ctrl);
+	/* All status2 sources are ACKed by msm_dp_ctrl_get_interrupt(). */
+	if (isr & DP_INTERRUPT_STATUS2)
+		ret = IRQ_HANDLED;
 
 	if (isr & DP_CTRL_INTR_READY_FOR_VIDEO) {
 		drm_dbg_dp(ctrl->drm_dev, "dp_video_ready\n");
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 8ea3d258a98f..40b2f6e120cf 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1091,23 +1091,24 @@ static irqreturn_t msm_dp_display_irq_handler(int irq, void *dev_id)
 	u32 hpd_isr_status;
 	unsigned long flags;
 	irqreturn_t ret = IRQ_HANDLED;
+	bool hpd_irq_pending;
 
 	hpd_isr_status = msm_dp_aux_get_hpd_intr_status(dp->aux);
+	hpd_irq_pending = hpd_isr_status & DP_DP_HPD_INT_MASK;
 
-	if (hpd_isr_status & 0x0F) {
+	if (hpd_irq_pending) {
 		drm_dbg_dp(dp->drm_dev, "type=%d isr=0x%x\n",
 			dp->msm_dp_display.connector_type, hpd_isr_status);
 
 		spin_lock_irqsave(&dp->irq_thread_lock, flags);
 		dp->hpd_isr_status |= hpd_isr_status;
-		ret = IRQ_WAKE_THREAD;
 		spin_unlock_irqrestore(&dp->irq_thread_lock, flags);
 	}
 
 	/* DP controller isr */
 	ret |= msm_dp_ctrl_isr(dp->ctrl, dp->panel);
 
-	return ret;
+	return hpd_irq_pending ? IRQ_WAKE_THREAD : ret;
 }
 
 static irqreturn_t msm_dp_display_irq_thread(int irq, void *dev_id)

-- 
2.43.0