Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756063AbaF3MlP (ORCPT ); Mon, 30 Jun 2014 08:41:15 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:53045 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932213AbaF3MbU (ORCPT ); Mon, 30 Jun 2014 08:31:20 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Mikulas Patocka , Tomi Valkeinen , Jiri Slaby Subject: [PATCH 3.12 126/181] matroxfb: perform a dummy read of M_STATUS Date: Mon, 30 Jun 2014 13:52:27 +0200 Message-Id: <3633bbaec56c99a04939d6088c711645a284c34c.1404128998.git.jslaby@suse.cz> X-Mailer: git-send-email 2.0.0 In-Reply-To: <61844d8e25eb8899b0836afa9796fa239db80f1f.1404128997.git.jslaby@suse.cz> References: <61844d8e25eb8899b0836afa9796fa239db80f1f.1404128997.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mikulas Patocka 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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: Jiri Slaby --- 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 -- 2.0.0 -- 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/