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Docs/EDID: Calculate CRC while building the code

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The previous version made it necessary to first generate an
EDID data set without correct CRC and then to fix the CRC in
a second step. This patch adds the CRC calculation to the
makefile in such a way that a correct EDID data set is generated
in a single build step. Successfully tested with all existing
and a couple of new data sets.

Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.de>
Reviewed-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Christoph Niedermaier 2018-11-05 09:48:35 +01:00 committed by Jonathan Corbet
parent d2f112a568
commit 8bed5a5cfc
8 changed files with 13 additions and 17 deletions
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1
Documentation/EDID/1024x768.S
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@ -39,6 +39,5 @@
#define ESTABLISHED_TIMING2_BITS 0x08 /* Bit 3 -> 1024x768 @60 Hz */
#define HSYNC_POL 0
#define VSYNC_POL 0
#define CRC 0x55
#include "edid.S"

1
Documentation/EDID/1280x1024.S
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@ -39,6 +39,5 @@
/* No ESTABLISHED_TIMINGx_BITS */
#define HSYNC_POL 1
#define VSYNC_POL 1
#define CRC 0xa0
#include "edid.S"

1
Documentation/EDID/1600x1200.S
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@ -39,6 +39,5 @@
/* No ESTABLISHED_TIMINGx_BITS */
#define HSYNC_POL 1
#define VSYNC_POL 1
#define CRC 0x9d
#include "edid.S"

1
Documentation/EDID/1680x1050.S
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@ -39,6 +39,5 @@
/* No ESTABLISHED_TIMINGx_BITS */
#define HSYNC_POL 1
#define VSYNC_POL 1
#define CRC 0x26
#include "edid.S"

1
Documentation/EDID/1920x1080.S
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@ -39,6 +39,5 @@
/* No ESTABLISHED_TIMINGx_BITS */
#define HSYNC_POL 1
#define VSYNC_POL 1
#define CRC 0x05
#include "edid.S"

1
Documentation/EDID/800x600.S
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@ -36,6 +36,5 @@
#define ESTABLISHED_TIMING1_BITS 0x01 /* Bit 0: 800x600 @ 60Hz */
#define HSYNC_POL 1
#define VSYNC_POL 1
#define CRC 0xc2
#include "edid.S"

9
Documentation/EDID/HOWTO.txt
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@ -47,12 +47,3 @@ EDID:
#define YBLANK vtotal-vdisp
#define YOFFSET vsyncstart-vdisp
#define YPULSE vsyncend-vsyncstart
The CRC value in the last line
#define CRC 0x55
also is a bit tricky. After a first version of the binary data set is
created, it must be checked with the "edid-decode" utility which will
most probably complain about a wrong CRC. Fortunately, the utility also
displays the correct CRC which must then be inserted into the source
file. After the make procedure is repeated, the EDID data set is ready
to be used.

15
Documentation/EDID/Makefile
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@ -15,10 +15,21 @@ clean:
%.o: %.S
@cc -c $^
%.bin: %.o
%.bin.nocrc: %.o
@objcopy -Obinary $^ $@
%.bin.ihex: %.o
%.crc: %.bin.nocrc
@list=$$(for i in `seq 1 127`; do head -c$$i $^ | tail -c1 \
| hexdump -v -e '/1 "%02X+"'; done); \
echo "ibase=16;100-($${list%?})%100" | bc >$@
%.p: %.crc %.S
@cc -c -DCRC="$$(cat $*.crc)" -o $@ $*.S
%.bin: %.p
@objcopy -Obinary $^ $@
%.bin.ihex: %.p
@objcopy -Oihex $^ $@
@dos2unix $@ 2>/dev/null