Provide workarounds to use DRM/KMS with broken graphics hardware

Index: linux-3.3-rc7/Documentation/EDID/1024x768.S
===================================================================
@@ -0,0 +1,44 @@
+/*
+   1024x768.S: EDID data set for standard 1024x768 60 Hz monitor
+
+   Copyright (C) 2011 Carsten Emde <[email protected]>
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
+*/
+
+/* EDID */
+#define VERSION 1
+#define REVISION 3
+
+/* Display */
+#define CLOCK 65000 /* kHz */
+#define XPIX 1024
+#define YPIX 768
+#define XY_RATIO XY_RATIO_4_3
+#define XBLANK 320
+#define YBLANK 38
+#define XOFFSET 8
+#define XPULSE 144
+#define YOFFSET (63+3)
+#define YPULSE (63+6)
+#define DPI 72
+#define VFREQ 60 /* Hz */
+#define TIMING_NAME "Linux XGA"
+#define ESTABLISHED_TIMINGS_BITS 0x08 /* Bit 3 -> 1024x768 @60 Hz */
+#define HSYNC_POL 0
+#define VSYNC_POL 0
+#define CRC 0x55
+
+#include "edid.S"

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Index: linux-3.3-rc7/Documentation/EDID/HOWTO.txt
===================================================================
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+In the good old days when graphics parameters were configured explicitly
+in a file called xorg.conf, even broken hardware could be managed.
+
+Today, with the advent of Kernel Mode Setting, a graphics board is
+either correctly working because all components follow the standards -
+or the computer is unusable, because the screen remains dark after
+booting or it displays the wrong area. Cases when this happens are:
+- The graphics board does not recognize the monitor.
+- The graphics board is unable to detect any EDID data.
+- The graphics board incorrectly forwards EDID data to the driver.
+- The monitor sends no or bogus EDID data.
+- A KVM sends its own EDID data instead of querying the connected monitor.
+Adding the kernel parameter "nomodeset" helps in most cases, but causes
+restrictions later on.
+
+As a remedy for such situations, the kernel configuration item
+CONFIG_DRM_LOAD_EDID_FIRMWARE was introduced. It allows to provide an
+individually prepared or corrected EDID data set in the /lib/firmware
+directory from where it is loaded via the firmware interface. The code
+(see drivers/gpu/drm/drm_edid_load.c) contains built-in data sets for
+commonly used screen resolutions (1024x768, 1280x1024, 1680x1050,
+1920x1080) as binary blobs, but the kernel source tree does not contain
+code to create these data. In order to elucidate the origin of the
+built-in binary EDID blobs and to facilitate the creation of individual
+data for a specific misbehaving monitor, commented sources and a
+Makefile environment are given here.
+
+To create binary EDID and C source code files from the existing data
+material, simply type "make".
+
+If you want to create your own EDID file, copy the file 1024x768.S and
+replace the settings with your own data. The CRC value in the last line
+  #define CRC 0x55
+is a bit tricky. After a first version of the binary data set is
+created, it must be 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.

Index: linux-3.3-rc7/Documentation/EDID/Makefile
===================================================================
@@ -0,0 +1,26 @@
+
+SOURCES	:= $(wildcard [0-9]*x[0-9]*.S)
+
+BIN	:= $(patsubst %.S, %.bin, $(SOURCES))
+
+IHEX	:= $(patsubst %.S, %.bin.ihex, $(SOURCES))
+
+CODE	:= $(patsubst %.S, %.c, $(SOURCES))
+
+all:	$(BIN) $(IHEX) $(CODE)
+
+clean:
+	@rm -f *.o *.bin.ihex *.bin *.c
+
+%.o:	%.S
+	@cc -c $^
+
+%.bin:	%.o
+	@objcopy -Obinary $^ $@
+
+%.bin.ihex:	%.o
+	@objcopy -Oihex $^ $@
+	@dos2unix $@ 2>/dev/null
+
+%.c:	%.bin
+	@echo "{" >$@; hexdump -f hex $^ >>$@; echo "};" >>$@

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Index: linux-3.3-rc7/Documentation/EDID/hex
===================================================================
@@ -0,0 +1 @@
+"\t" 8/1 "0x%02x, " "\n"

Index: linux-3.3-rc7/Documentation/kernel-parameters.txt
===================================================================
@@ -713,6 +713,18 @@ bytes respectively. Such letter suffixes
 			The filter can be disabled or changed to another
 			driver later using sysfs.
 
+	drm_kms_helper.edid_firmware=<file>
+			Broken monitors, graphic adapters and KVMs may
+			send no or broken EDID data sets. This parameter
+			allows to specify an EDID data set in the
+			/lib/firmware directory that is used instead.
+			Generic built-in EDID data sets are used, if one of
+			edid/1024x768.bin, edid/1280x1024.bin,
+			edid/1680x1050.bin, or edid/1920x1080.bin is given
+			and no file with the same name exists. Details and
+			instructions how to build your own EDID data are
+			given in Documentation/EDID/HOWTO.txt.
+
 	dscc4.setup=	[NET]
 
 	earlycon=	[KNL] Output early console device and options.

Index: linux-3.3-rc7/drivers/gpu/drm/Kconfig
===================================================================
@@ -27,6 +27,18 @@ config DRM_KMS_HELPER
 	help
 	  FB and CRTC helpers for KMS drivers.
 
+config DRM_LOAD_EDID_FIRMWARE
+	bool "Allow to specify an EDID data set instead of probing for it"
+	depends on DRM_KMS_HELPER
+	help
+	  Say Y here, if you want to use EDID data to be loaded from the
+	  /lib/firmware directory or one of the provided built-in
+	  data sets. This may be necessary, if the graphics adapter or
+	  monitor are unable to provide appropriate EDID data. Since this
+	  feature is provided as a workaround for broken hardware, the
+	  default case is N. Details and instructions how to build your own
+	  EDID data are given in Documentation/EDID/HOWTO.txt.
+
 config DRM_TTM
 	tristate
 	depends on DRM

Index: linux-3.3-rc7/drivers/gpu/drm/Makefile
===================================================================
@@ -17,6 +17,9 @@ drm-y       :=	drm_auth.o drm_buffer.o d
 drm-$(CONFIG_COMPAT) += drm_ioc32.o
 
 drm_kms_helper-y := drm_fb_helper.o drm_crtc_helper.o drm_dp_i2c_helper.o
+ifdef CONFIG_DRM_LOAD_EDID_FIRMWARE
+drm_kms_helper-y += drm_edid_load.o
+endif
 
 obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o