This is a note to let you know that I've just added the patch titled
matroxfb: perform a dummy read of M_STATUS
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
matroxfb-perform-a-dummy-read-of-m_status.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 972754cfaee94d6e25acf94a497bc0a864d91b7e Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Thu, 15 May 2014 06:58:24 -0400
Subject: matroxfb: perform a dummy read of M_STATUS
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit 972754cfaee94d6e25acf94a497bc0a864d91b7e upstream.
I had occasional screen corruption with the matrox framebuffer driver and
I found out that the reason for the corruption is that the hardware
blitter accesses the videoram while it is being written to.
The matrox driver has a macro WaitTillIdle() that should wait until the
blitter is idle, but it sometimes doesn't work. I added a dummy read
mga_inl(M_STATUS) to WaitTillIdle() to fix the problem. The dummy read
will flush the write buffer in the PCI chipset, and the next read of
M_STATUS will return the hardware status.
Since applying this patch, I had no screen corruption at all.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/video/matrox/matroxfb_base.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/video/matrox/matroxfb_base.h
+++ b/drivers/video/matrox/matroxfb_base.h
@@ -698,7 +698,7 @@ void matroxfb_unregister_driver(struct m
#define mga_fifo(n) do {} while ((mga_inl(M_FIFOSTATUS) & 0xFF) < (n))
-#define WaitTillIdle() do {} while (mga_inl(M_STATUS) & 0x10000)
+#define WaitTillIdle() do { mga_inl(M_STATUS); do {} while (mga_inl(M_STATUS) & 0x10000); } while (0)
/* code speedup */
#ifdef CONFIG_FB_MATROX_MILLENIUM
Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are
queue-3.4/matroxfb-perform-a-dummy-read-of-m_status.patch
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