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[EDID] Ignore reserved bits in deciding monitor vs detailed timing descriptor.

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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.
This commit is contained in:
Eric Anholt 2007-09-24 20:23:35 -07:00
parent 27ad5d74c2
commit 988f446fe0
1 changed files with 8 additions and 1 deletions
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9
hw/xfree86/ddc/edid.h
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@ -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)