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>
The problem was found when EDID data sets for displays other
than the provided samples were generated. The patch has
no effect on the provided samples that still match the data
used in drivers/gpu/drm/drm_edid_load.c.
The provided samples use small values for XOFFSET, XPULSE,
YOFFSET and YPULSE, where the error doesn't occur. This fix
corrects the use of that values in case of high values, because
the most significant bits were treated incorrectly.
So in edid.S msbs4 should use bit 8 and 9 of XOFFSET and XPULS.
For YOFFSET and YPULSE msbs4 should use bit 4 and 5.
lsbs2 was introduced for a better overview, without
functional change.
Removing also the useless value 63 of all files, because
it is added in the *.S description files and then it is
subtracted in edid.S.
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>
The 800x600 (SVGA) screen resolution was lacking in the set of
built-in selectable EDID screen resolutions that can be used to
repair misbehaving monitor firmware.
This patch adds the related data set and expands the documentation.
Note that the SVGA bit occupies a different byte to all the existing
users of the established timing bits forcing a rework of the
ESTABLISHED_TIMINGS_BITS macro.
Tested new EDID on an aged (and misbehaving) industrial LCD panel;
existing EDIDs still pass edid-decode's checksum checks.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: David Airlie <airlied@linux.ie>
Cc: Carsten Emde <C.Emde@osadl.org>
Cc: linux-doc@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Broken monitors and/or broken graphic boards may send erroneous or no
EDID data. This also applies to broken KVM devices that are unable to
correctly forward the EDID data of the connected monitor but invent
their own fantasy data.
This patch allows to specify an EDID data set to be used instead of
probing the monitor for it. It contains built-in data sets of frequently
used screen resolutions. In addition, a particular EDID data set may be
provided in the /lib/firmware directory and loaded via the firmware
interface. The name is passed to the kernel as module parameter of the
drm_kms_helper module either when loaded
options drm_kms_helper edid_firmware=edid/1280x1024.bin
or as kernel commandline parameter
drm_kms_helper.edid_firmware=edid/1280x1024.bin
It is also possible to restrict the usage of a specified EDID data set
to a particular connector. This is done by prepending the name of the
connector to the name of the EDID data set using the syntax
edid_firmware=[<connector>:]<edid>
such as, for example,
edid_firmware=DVI-I-1:edid/1920x1080.bin
in which case no other connector will be affected.
The built-in data sets are
Resolution Name
--------------------------------
1024x768 edid/1024x768.bin
1280x1024 edid/1280x1024.bin
1680x1050 edid/1680x1050.bin
1920x1080 edid/1920x1080.bin
They are ignored, if a file with the same name is available in the
/lib/firmware directory.
The built-in EDID data sets are based on standard timings that may not
apply to a particular monitor and even crash it. Ideally, EDID data of
the connected monitor should be used. They may be obtained through the
drm/cardX/cardX-<connector>/edid entry in the /sys/devices PCI directory
of a correctly working graphics adapter.
It is even possible to specify the name of an EDID data set on-the-fly
via the /sys/module interface, e.g.
echo edid/myedid.bin >/sys/module/drm_kms_helper/parameters/edid_firmware
The new screen mode is considered when the related kernel function is
called for the first time after the change. Such calls are made when the
X server is started or when the display settings dialog is opened in an
already running X server.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
