[PATCH] fbdev: Resurrect hooks to get EDID from firmware

For the i386, code is already present in video.S that gets the EDID from the
video BIOS.  Make this visible so drivers can also use this data as fallback
when i2c does not work.

To ensure that the EDID block is returned for the primary graphics adapter
only, by check if the IORESOURCE_ROM_SHADOW flag is set.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/boot/video.S

@@ -1949,7 +1949,7 @@ store_edid:
 	movw	$0x4f15, %ax                    # do VBE/DDC
 	movw	$0x01, %bx
 	movw	$0x00, %cx
-	movw    $0x01, %dx
+	movw    $0x00, %dx
 	movw	$0x140, %di
 	int	$0x10
 

arch/i386/kernel/setup.c

@@ -139,6 +139,7 @@ struct sys_desc_table_struct {
 	unsigned char table[0];
 };
 struct edid_info edid_info;
+EXPORT_SYMBOL_GPL(edid_info);
 struct ist_info ist_info;
 #if defined(CONFIG_X86_SPEEDSTEP_SMI) || \
 	defined(CONFIG_X86_SPEEDSTEP_SMI_MODULE)

drivers/video/fbmon.c

@@ -29,6 +29,7 @@
 #include <linux/tty.h>
 #include <linux/fb.h>
 #include <linux/module.h>
+#include <video/edid.h>
 #ifdef CONFIG_PPC_OF
 #include <linux/pci.h>
 #include <asm/prom.h>
@@ -1251,9 +1252,41 @@ int fb_validate_mode(const struct fb_var_screeninfo *var, struct fb_info *info)
 		-EINVAL : 0;
 }
 
+#if defined(__i386__)
+#include <linux/pci.h>
+
+/*
+ * We need to ensure that the EDID block is only returned for
+ * the primary graphics adapter.
+ */
+
+const unsigned char *fb_firmware_edid(struct device *device)
+{
+	struct pci_dev *dev = NULL;
+	struct resource *res = NULL;
+	unsigned char *edid = NULL;
+
+	if (device)
+		dev = to_pci_dev(device);
+
+	if (dev)
+		res = &dev->resource[PCI_ROM_RESOURCE];
+
+	if (res && res->flags & IORESOURCE_ROM_SHADOW)
+		edid = edid_info.dummy;
+
+	return edid;
+}
+#else
+const unsigned char *fb_firmware_edid(struct device *device)
+{
+	return NULL;
+}
+#endif /* _i386_ */
+
 EXPORT_SYMBOL(fb_parse_edid);
 EXPORT_SYMBOL(fb_edid_to_monspecs);
-
+EXPORT_SYMBOL(fb_firmware_edid);
 EXPORT_SYMBOL(fb_get_mode);
 EXPORT_SYMBOL(fb_validate_mode);
 EXPORT_SYMBOL(fb_destroy_modedb);

include/linux/fb.h

@@ -859,7 +859,9 @@ extern int fb_get_mode(int flags, u32 val, struct fb_var_screeninfo *var,
 extern int fb_validate_mode(const struct fb_var_screeninfo *var,
 			    struct fb_info *info);
 extern int fb_parse_edid(unsigned char *edid, struct fb_var_screeninfo *var);
-extern void fb_edid_to_monspecs(unsigned char *edid, struct fb_monspecs *specs);
+extern const unsigned char *fb_firmware_edid(struct device *device);
+extern void fb_edid_to_monspecs(unsigned char *edid,
+				struct fb_monspecs *specs);
 extern void fb_destroy_modedb(struct fb_videomode *modedb);
 
 /* drivers/video/modedb.c */