linux-kernel - [PATCH] drm/vc4: Move IRQ enable to PM path

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Message-Id: <1514563543-32511-1-git-send-email-stschake@gmail.com>
Date:   Fri, 29 Dec 2017 17:05:43 +0100
From:   Stefan Schake <stschake@...il.com>
To:     Eric Anholt <eric@...olt.net>, David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     linux-rpi-kernel@...ts.infradead.org,
        Stefan Schake <stschake@...il.com>
Subject: [PATCH] drm/vc4: Move IRQ enable to PM path

We were calling enable_irq on bind, where it was already enabled previously
by the IRQ helper. Additionally, dev->irq is not set correctly until after
postinstall and so was always zero here, triggering a warning in 4.15.
Fix both by moving the enable to the power management resume path, where we
know there was a previous disable invocation during suspend.

Fixes: 253696ccd613 ("drm/vc4: Account for interrupts in flight")
Signed-off-by: Stefan Schake <stschake@...il.com>
---
I tested replacing the enable/disable dance with just synchronize_irq,
but that only made the original kernel OOPS more sporadic.

 drivers/gpu/drm/vc4/vc4_irq.c | 3 ---
 drivers/gpu/drm/vc4/vc4_v3d.c | 3 +++
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_irq.c b/drivers/gpu/drm/vc4/vc4_irq.c
index 26eddbb..3dd62d7 100644
--- a/drivers/gpu/drm/vc4/vc4_irq.c
+++ b/drivers/gpu/drm/vc4/vc4_irq.c
@@ -209,9 +209,6 @@
 {
 	struct vc4_dev *vc4 = to_vc4_dev(dev);
 
-	/* Undo the effects of a previous vc4_irq_uninstall. */
-	enable_irq(dev->irq);
-
 	/* Enable both the render done and out of memory interrupts. */
 	V3D_WRITE(V3D_INTENA, V3D_DRIVER_IRQS);
 
diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index 622cd43..493f392b 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -327,6 +327,9 @@ static int vc4_v3d_runtime_resume(struct device *dev)
 		return ret;
 
 	vc4_v3d_init_hw(vc4->dev);
+
+	/* We disabled the IRQ as part of vc4_irq_uninstall in suspend. */
+	enable_irq(vc4->dev->irq);
 	vc4_irq_postinstall(vc4->dev);
 
 	return 0;
-- 
1.9.1