linux-kernel - [PATCH 3.2 017/131] drm/radeon: fix irq ring buffer overflow handling

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Message-ID: <lsq.1410438733.837598570@decadent.org.uk>
Date:	Thu, 11 Sep 2014 13:32:13 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Michel Dänzer" <michel.daenzer@....com>,
	"Christian König" <christian.koenig@....com>,
	"Alex Deucher" <alexander.deucher@....com>
Subject: [PATCH 3.2 017/131] drm/radeon: fix irq ring buffer overflow handling

3.2.63-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Christian König <christian.koenig@....com>

commit e8c214d22e76dd0ead38f97f8d2dc09aac70d651 upstream.

We must mask out the overflow bit as well, otherwise
the wptr will never match the rptr again and the interrupt
handler will loop forever.

Signed-off-by: Christian König <christian.koenig@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Reviewed-by: Michel Dänzer <michel.daenzer@....com>
[bwh: Backported to 3.2: drop changes for unsupported GPUs]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/gpu/drm/radeon/evergreen.c
+++ b/drivers/gpu/drm/radeon/evergreen.c
@@ -2765,6 +2765,7 @@ static u32 evergreen_get_ih_wptr(struct
 		tmp = RREG32(IH_RB_CNTL);
 		tmp |= IH_WPTR_OVERFLOW_CLEAR;
 		WREG32(IH_RB_CNTL, tmp);
+		wptr &= ~RB_OVERFLOW;
 	}
 	return (wptr & rdev->ih.ptr_mask);
 }
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -3280,6 +3280,7 @@ static u32 r600_get_ih_wptr(struct radeo
 		tmp = RREG32(IH_RB_CNTL);
 		tmp |= IH_WPTR_OVERFLOW_CLEAR;
 		WREG32(IH_RB_CNTL, tmp);
+		wptr &= ~RB_OVERFLOW;
 	}
 	return (wptr & rdev->ih.ptr_mask);
 }

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