linux-kernel - [PATCH] vga16fb: refuse to load in face of other driver controlling primary card

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Message-ID: <20100720191923.GA11056@joi.lan>
Date:	Tue, 20 Jul 2010 21:19:23 +0200
From:	Marcin Slusarz <marcin.slusarz@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-fbdev@...r.kernel.org, nouveau@...ts.freedesktop.org
Subject: [PATCH] vga16fb: refuse to load in face of other driver
 controlling primary card

We don't want vga16fb to mess with hardware initialized by other driver.
Detect it and refuse to load.
It fixes nouveau interrupt storm on some machines.

Signed-off-by: Marcin Slusarz <marcin.slusarz@...il.com>
---
 drivers/video/vga16fb.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/drivers/video/vga16fb.c b/drivers/video/vga16fb.c
index 28ccab4..4505446 100644
--- a/drivers/video/vga16fb.c
+++ b/drivers/video/vga16fb.c
@@ -22,6 +22,7 @@
 #include <linux/platform_device.h>
 #include <linux/screen_info.h>
 
+#include <asm/fb.h>
 #include <asm/io.h>
 #include <video/vga.h>
 
@@ -1415,7 +1416,7 @@ static struct platform_device *vga16fb_device;
 
 static int __init vga16fb_init(void)
 {
-	int ret;
+	int ret, i;
 #ifndef MODULE
 	char *option = NULL;
 
@@ -1424,6 +1425,16 @@ static int __init vga16fb_init(void)
 
 	vga16fb_setup(option);
 #endif
+	for (i = 0 ; i < FB_MAX; i++) {
+		if (!registered_fb[i])
+			continue;
+		if (fb_is_primary_device(registered_fb[i])) {
+			printk(KERN_INFO "vga16fb: %s is driving the primary card, refusing to load\n",
+				registered_fb[i]->fix.id);
+			return -EBUSY;
+		}
+	}
+
 	ret = platform_driver_register(&vga16fb_driver);
 
 	if (!ret) {
-- 
1.7.1


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