From: Martin Decky <martin@decky.cz>
To: linux-fbdev@vger.kernel.org
Subject: [PATCH] Fix EDID macros H_SYNC_WIDTH and H_SYNC_OFFSET
Date: Sun, 13 Feb 2011 19:28:40 +0000 [thread overview]
Message-ID: <4D5830E8.50900@decky.cz> (raw)
From: Martin Decky <martin@decky.cz>
The macros for getting the values for horizontal sync width and offset
do not respect the EDID specification. Both these values are 10 bit
values according to [1], not 6 bit values. The lower 8 bits are stored
in byte 8 and byte 9 of the DTD respectively, while two additional bits
for each value are stored in byte 11. The original macros just slammed
the bits together.
Although the original macros usually worked fine because the higher two
bits are rarely used, it can cause severe problems on plasma panels
running at 1920x1080 @ 50 Hz with drivers that rely on the correct
parsing of the EDID data by fbmon.c (e.g. udlfb).
The patch should apply cleanly to both the fbdev-2.6.git branch and
linux-next.git branch.
[1] VESA Enhanced Extended Display Identification Data Standard,
Release A, Revision 2, page 34, notes 7 & 8, VESA, Sep 2006
Signed-off-by: Martin Decky <martin@decky.cz>
----
diff -Naurp fbdev-2.6.orig/drivers/video/edid.h fbdev-2.6/drivers/video/edid.h
--- fbdev-2.6.orig/drivers/video/edid.h 2011-02-13 19:45:22.000000000 +0100
+++ fbdev-2.6/drivers/video/edid.h 2011-02-13 19:56:02.080350929 +0100
@@ -101,8 +101,8 @@
#define V_SYNC_WIDTH COMBINE_HI_4LO( V_SYNC_WIDTH_HI, V_SYNC_WIDTH_LO )
#define V_SYNC_OFFSET COMBINE_HI_4LO( V_SYNC_OFFSET_HI, V_SYNC_OFFSET_LO )
-#define H_SYNC_WIDTH COMBINE_HI_4LO( H_SYNC_WIDTH_HI, H_SYNC_WIDTH_LO )
-#define H_SYNC_OFFSET COMBINE_HI_4LO( H_SYNC_OFFSET_HI, H_SYNC_OFFSET_LO )
+#define H_SYNC_WIDTH COMBINE_HI_8LO( H_SYNC_WIDTH_HI, H_SYNC_WIDTH_LO )
+#define H_SYNC_OFFSET COMBINE_HI_8LO( H_SYNC_OFFSET_HI, H_SYNC_OFFSET_LO )
#define H_SIZE_LO (unsigned)block[ 12 ]
#define V_SIZE_LO (unsigned)block[ 13 ]
reply other threads:[~2011-02-13 19:28 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4D5830E8.50900@decky.cz \
--to=martin@decky.cz \
--cc=linux-fbdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).