Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030357AbaGCKM2 (ORCPT ); Thu, 3 Jul 2014 06:12:28 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:51611 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758265AbaGCJVp (ORCPT ); Thu, 3 Jul 2014 05:21:45 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Mikulas Patocka , Tomi Valkeinen , Luis Henriques Subject: [PATCH 3.11 039/198] matroxfb: perform a dummy read of M_STATUS Date: Thu, 3 Jul 2014 10:18:02 +0100 Message-Id: <1404379241-8590-40-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> References: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.13 -stable 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 Signed-off-by: Luis Henriques --- drivers/video/matrox/matroxfb_base.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/video/matrox/matroxfb_base.h b/drivers/video/matrox/matroxfb_base.h index 556d96ce40bf..89a8a89a5eb2 100644 --- a/drivers/video/matrox/matroxfb_base.h +++ b/drivers/video/matrox/matroxfb_base.h @@ -698,7 +698,7 @@ void matroxfb_unregister_driver(struct matroxfb_driver* drv); #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 -- 1.9.1 -- 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/