Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755814AbaGHTIp (ORCPT ); Tue, 8 Jul 2014 15:08:45 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:54038 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755649AbaGHTIi (ORCPT ); Tue, 8 Jul 2014 15:08:38 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Tomi Valkeinen" , "Mikulas Patocka" Date: Tue, 08 Jul 2014 20:01:50 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 012/125] matroxfb: perform a dummy read of M_STATUS In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.61-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka 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 Signed-off-by: Tomi Valkeinen [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings --- drivers/video/fbdev/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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/