[PATCH 7/7] uvesafb: try to set mode with default timings if setting it with our own timings failed

[Michal Januszewski <spock@gentoo.org>]

Sometimes the BIOS might not perform the mode switch correctly because of
the timings that we requested.  In case this happens, try to set the video
mode with the default timings instead.

Signed-off-by: Michal Januszewski <spock@gentoo.org>
---
diff --git a/drivers/video/uvesafb.c b/drivers/video/uvesafb.c
index 2e5f1b5..853323e 100644
--- a/drivers/video/uvesafb.c
+++ b/drivers/video/uvesafb.c
@@ -1218,6 +1218,7 @@ static int uvesafb_set_par(struct fb_info *info)
 	task = uvesafb_prep();
 	if (!task)
 		return -ENOMEM;
+setmode:
 	task->t.regs.eax = 0x4f02;
 	task->t.regs.ebx = mode->mode_id | 0x4000;	/* use LFB */
 
@@ -1260,10 +1261,25 @@ static int uvesafb_set_par(struct fb_info *info)
 
 	err = uvesafb_exec(task);
 	if (err || (task->t.regs.eax & 0xffff) != 0x004f) {
-		printk(KERN_ERR "uvesafb: mode switch failed (eax=0x%x, "
-				"err=%d)\n", task->t.regs.eax, err);
-		err = -EINVAL;
-		goto out;
+		/*
+		 * The mode switch might have failed because we tried to
+		 * use our own timings.  Try again with the default timings.
+		 */
+		if (crtc != NULL) {
+			printk(KERN_WARNING "uvesafb: mode switch failed "
+				"(eax=0x%x, err=%d). Trying again with "
+				"default timings.\n", task->t.regs.eax, err);
+			uvesafb_reset(task);
+			kfree(crtc);
+			crtc = NULL;
+			info->var.pixclock = 0;
+			goto setmode;
+		} else {
+			printk(KERN_ERR "uvesafb: mode switch failed (eax="
+				"0x%x, err=%d)\n", task->t.regs.eax, err);
+			err = -EINVAL;
+			goto out;
+		}
 	}
 	par->mode_idx = i;


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