From 988f446fe00ac2b92c484a4440613dd82191eadd Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Mon, 24 Sep 2007 20:23:35 -0700 Subject: [PATCH] [EDID] Ignore reserved bits in deciding monitor vs detailed timing descriptor. Even though they're defined to zero by the spec, we've seen an EDID block where the (empty) ASCII strings were stuffed in a byte early, leading to the descriptor being considered a detailed timing instead. --- hw/xfree86/ddc/edid.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/hw/xfree86/ddc/edid.h b/hw/xfree86/ddc/edid.h index 0b6a15af04..4487273cd9 100644 --- a/hw/xfree86/ddc/edid.h +++ b/hw/xfree86/ddc/edid.h @@ -190,7 +190,14 @@ /* EDID Ver. >= 1.2 */ -#define _IS_MONITOR_DESC(x) (x[0] == 0 && x[1] == 0 && x[2] == 0 && x[4] == 0) +/** + * Returns true if the pointer is the start of a monitor descriptor block + * instead of a detailed timing descriptor. + * + * Checking the reserved pad fields for zeroes fails on some monitors with + * broken empty ASCII strings. Only the first two bytes are reliable. + */ +#define _IS_MONITOR_DESC(x) (x[0] == 0 && x[1] == 0) #define IS_MONITOR_DESC _IS_MONITOR_DESC(c) #define _PIXEL_CLOCK(x) (x[0] + (x[1] << 8)) * 10000 #define PIXEL_CLOCK _PIXEL_CLOCK(c)