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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Marc Zyngier <marc.zyngier@arm.com>,
        Heiko Stuebner <heiko@sntech.de>
Subject: [PATCH 4.9 69/95] drm/rockchip: Clear all interrupts before requesting the IRQ
Date:   Sun, 22 Apr 2018 15:53:38 +0200
Message-Id: <20180422135213.252429672@linuxfoundation.org>
In-Reply-To: <20180422135210.432103639@linuxfoundation.org>
References: <20180422135210.432103639@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@arm.com>

commit 5f9e93fed4d45e9a8f84728aff1a8f2ab8922902 upstream.

Calling request_irq() followed by disable_irq() is usually a bad idea,
specially if the interrupt can be pending, and you're not yet in a
position to handle it.

This is exactly what happens on my kevin system when rebooting in a
second kernel using kexec: Some interrupt is left pending from
the previous kernel, and we take it too early, before disable_irq()
could do anything.

Let's clear the pending interrupts as we initialize the HW, and move
the interrupt request after that point. This ensures that we're in
a sane state when the interrupt is requested.

Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
[adapted to recent rockchip-drm changes]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20180220130120.5254-2-marc.zyngier@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/rockchip/rockchip_drm_vop.c |   23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -1386,6 +1386,9 @@ static int vop_initial(struct vop *vop)
 	usleep_range(10, 20);
 	reset_control_deassert(ahb_rst);
 
+	VOP_INTR_SET_TYPE(vop, clear, INTR_MASK, 1);
+	VOP_INTR_SET_TYPE(vop, enable, INTR_MASK, 0);
+
 	memcpy(vop->regsbak, vop->regs, vop->len);
 
 	for (i = 0; i < vop_data->table_size; i++)
@@ -1541,17 +1544,9 @@ static int vop_bind(struct device *dev,
 
 	mutex_init(&vop->vsync_mutex);
 
-	ret = devm_request_irq(dev, vop->irq, vop_isr,
-			       IRQF_SHARED, dev_name(dev), vop);
-	if (ret)
-		return ret;
-
-	/* IRQ is initially disabled; it gets enabled in power_on */
-	disable_irq(vop->irq);
-
 	ret = vop_create_crtc(vop);
 	if (ret)
-		goto err_enable_irq;
+		return ret;
 
 	pm_runtime_enable(&pdev->dev);
 
@@ -1561,13 +1556,19 @@ static int vop_bind(struct device *dev,
 		goto err_disable_pm_runtime;
 	}
 
+	ret = devm_request_irq(dev, vop->irq, vop_isr,
+			       IRQF_SHARED, dev_name(dev), vop);
+	if (ret)
+		goto err_disable_pm_runtime;
+
+	/* IRQ is initially disabled; it gets enabled in power_on */
+	disable_irq(vop->irq);
+
 	return 0;
 
 err_disable_pm_runtime:
 	pm_runtime_disable(&pdev->dev);
 	vop_destroy_crtc(vop);
-err_enable_irq:
-	enable_irq(vop->irq); /* To balance out the disable_irq above */
 	return ret;
 }