linux-kernel - [PATCH 5.4 039/244] drm/panfrost: Clear MMU irqs before handling the fault

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Message-Id: <20210512144744.303606033@linuxfoundation.org>
Date:   Wed, 12 May 2021 16:46:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Steven Price <steven.price@....com>
Subject: [PATCH 5.4 039/244] drm/panfrost: Clear MMU irqs before handling the fault

From: Boris Brezillon <boris.brezillon@...labora.com>

commit 3aa0a80fc692c9959c261f4c5bfe9c23ddd90562 upstream.

When a fault is handled it will unblock the GPU which will continue
executing its shader and might fault almost immediately on a different
page. If we clear interrupts after handling the fault we might miss new
faults, so clear them before.

Cc: <stable@...r.kernel.org>
Fixes: 187d2929206e ("drm/panfrost: Add support for GPU heap allocations")
Signed-off-by: Boris Brezillon <boris.brezillon@...labora.com>
Reviewed-by: Steven Price <steven.price@....com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210205111757.585248-2-boris.brezillon@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/panfrost/panfrost_mmu.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -600,6 +600,8 @@ static irqreturn_t panfrost_mmu_irq_hand
 		access_type = (fault_status >> 8) & 0x3;
 		source_id = (fault_status >> 16);
 
+		mmu_write(pfdev, MMU_INT_CLEAR, mask);
+
 		/* Page fault only */
 		ret = -1;
 		if ((status & mask) == BIT(i) && (exception_type & 0xF8) == 0xC0)
@@ -623,8 +625,6 @@ static irqreturn_t panfrost_mmu_irq_hand
 				access_type, access_type_name(pfdev, fault_status),
 				source_id);
 
-		mmu_write(pfdev, MMU_INT_CLEAR, mask);
-
 		status &= ~mask;
 	}