EDID(9) BSD Kernel Developer's Manual EDID(9)NAMEedid — VESA Extended Display Identification Data
SYNOPSIS
#include <dev/videomode/edidvar.h>
#include <dev/videomode/edidreg.h>
int
edid_is_valid(uint8_t *data);
int
edid_parse(uint8_t *data, struct edid_info *info);
void
edid_print(struct edid_info *info);
DESCRIPTION
These functions provide support parsing the Extended Display Identifica‐
tion Data which describes a display device such as a monitor or flat
panel display.
The edid_is_valid() function simply tests if the EDID block in data con‐
tains valid data. This test includes a verification of the checksum, and
that valid vendor and product idenfication data is present. The data
block contain at least 128 bytes.
The edid_parse() function parses the supplied data block (which again,
must be at least 128 bytes), writing the relevant data into the structure
pointed to by info.
The edid_print() function prints the data in the given info structure to
the console device.
RETURN VALUES
The edid_is_valid() function returns 0 if the data block is valid, and
EINVAL otherwise. The edid_parse() function returns zero if the data was
successfully parsed, and non-zero otherwise.
CODE REFERENCES
The EDID subsystem is implemented within the file
sys/dev/videomode/edid.c.
The EDID subsystem also makes use of VESA Generalized Timing Formula
located located in sys/dev/videomode/vesagtf.c and the generic videomode
database located in sys/dev/videomode/videomode.c.
EXAMPLES
The following code uses these functions to retrieve and print information
about a monitor:
struct edid_info info;
i2c_tag_t tag;
char buffer[128];
...
/* initialize i2c tag... */
...
if ((ddc_read_edid(tag, buffer, 128) == 0) &&
(edid_parse(buffer, &info) == 0))
edid_print(info);
...
SEE ALSOddc(9), iic(9)HISTORY
These routines were added in NetBSD 4.0.
AUTHORS
Garrett D'Amore ⟨gdamore@NetBSD.org⟩
BSD May 11, 2006 BSD