fbcon: logo: disable logo at boot

Add logo.nologo kernel boot option to disable the logo in order to provide
more screen space for kernel messages; especially useful when debugging and
screen space is more critical.

newport_con driver changes are untested.

[akpm@linux-foundation.org: cleanups, coding-style fixes]
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/kernel-parameters.txt

@@ -911,6 +911,11 @@ and is between 256 and 4096 characters. It is defined in the file
 			n must be a power of two.  The default size
 			is set in the kernel config file.
 
+	logo.nologo	[FB] Disables display of the built-in Linux logo.
+			This may be used to provide more screen space for
+			kernel log messages and is useful when debugging
+			kernel boot problems.
+
 	lp=0		[LP]	Specify parallel ports to use, e.g,
 	lp=port[,port...]	lp=none,parport0 (lp0 not configured, lp1 uses
 	lp=reset		first parallel port). 'lp=0' disables the

drivers/video/console/newport_con.c

@@ -98,14 +98,19 @@ static inline void newport_init_cmap(void)
 	}
 }
 
-static void newport_show_logo(void)
+static struct linux_logo *newport_show_logo(void)
 {
 #ifdef CONFIG_LOGO_SGI_CLUT224
 	const struct linux_logo *logo = fb_find_logo(8);
-	const unsigned char *clut = logo->clut;
-	const unsigned char *data = logo->data;
+	const unsigned char *clut;
+	const unsigned char *data;
 	unsigned long i;
 
+	if (!logo)
+		return NULL;
+	*clut = logo->clut;
+	*data = logo->data;
+
 	for (i = 0; i < logo->clutsize; i++) {
 		newport_bfwait(npregs);
 		newport_cmap_setaddr(npregs, i + 0x20);
@@ -123,6 +128,8 @@ static void newport_show_logo(void)
 
 	for (i = 0; i < logo->width*logo->height; i++)
 		npregs->go.hostrw0 = *data++ << 24;
+
+	return logo;
 #endif /* CONFIG_LOGO_SGI_CLUT224 */
 }
 
@@ -465,10 +472,11 @@ static int newport_switch(struct vc_data *vc)
 	npregs->cset.topscan = 0x3ff;
 
 	if (!logo_drawn) {
-		newport_show_logo();
+		if (newport_show_logo()) {
 			logo_drawn = 1;
 			logo_active = 1;
 		}
+	}
 
 	return 1;
 }

drivers/video/logo/logo.c

@@ -34,6 +34,10 @@ extern const struct linux_logo logo_superh_vga16;
 extern const struct linux_logo logo_superh_clut224;
 extern const struct linux_logo logo_m32r_clut224;
 
+static int nologo;
+module_param(nologo, bool, 0);
+MODULE_PARM_DESC(nologo, "Disables startup logo");
+
 /* logo's are marked __initdata. Use __init_refok to tell
  * modpost that it is intended that this function uses data
  * marked __initdata.
@@ -42,6 +46,9 @@ const struct linux_logo * __init_refok fb_find_logo(int depth)
 {
 	const struct linux_logo *logo = NULL;
 
+	if (nologo)
+		return NULL;
+
 	if (depth >= 1) {
 #ifdef CONFIG_LOGO_LINUX_MONO
 		/* Generic Linux logo */