Provide workarounds to use DRM/KMS with broken graphics hardware
Subsystems (3)
v6 cover Provide workarounds to use DRM/KMS with broken graphics hardware
Changes from V5 to V6:
1. The use of a particular EDID data set can now be restricted to a given connector using the syntax edid_firmware=[<connector>:]<edid>
as suggested by Thomas Reim.
2. The patches to introduce a module parameter and a quirk to cope with an inverted brightness variable of some i915 graphics adapters are no longer part of this patch series.
Thanks,
Carsten.
PATCH v6 1/1 drivers-gpu-drm-allow-to-load-edid-firmware.patch
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.
--- Documentation/EDID/1024x768.S | 44 ++++++ Documentation/EDID/1280x1024.S | 44 ++++++ Documentation/EDID/1680x1050.S | 44 ++++++ Documentation/EDID/1920x1080.S | 44 ++++++ Documentation/EDID/HOWTO.txt | 39 +++++ Documentation/EDID/Makefile | 26 +++ Documentation/EDID/edid.S | 261 ++++++++++++++++++++++++++++++++++++ Documentation/EDID/hex | 1 Documentation/kernel-parameters.txt | 15 ++ drivers/gpu/drm/Kconfig | 12 + drivers/gpu/drm/Makefile | 3 drivers/gpu/drm/drm_crtc_helper.c | 8 - drivers/gpu/drm/drm_edid.c | 4 drivers/gpu/drm/drm_edid_load.c | 250 ++++++++++++++++++++++++++++++++++ include/drm/drm_crtc.h | 1 include/drm/drm_edid.h | 1 16 files changed, 794 insertions(+), 3 deletions(-)
Documentation/EDID/1024x768.S new file +44 -0
@@ -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"
Documentation/EDID/1280x1024.S new file +44 -0
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Documentation/EDID/1680x1050.S new file +44 -0
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Documentation/EDID/1920x1080.S new file +44 -0
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Documentation/EDID/HOWTO.txt new file +39 -0
@@ -0,0 +1,39 @@ +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.
Documentation/EDID/Makefile new file +26 -0
@@ -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 "};" >>$@
Documentation/EDID/edid.S new file +261 -0
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Documentation/EDID/hex new file +1 -0
@@ -0,0 +1 @@ +"\t" 8/1 "0x%02x, " "\n"
Documentation/kernel-parameters.txt +15 -0
@@ -713,6 +713,21 @@ bytes respectively. Such letter suffixes The filter can be disabled or changed to another driver later using sysfs. + drm_kms_helper.edid_firmware=[<connector>:]<file> + Broken monitors, graphic adapters and KVMs may + send no or incorrect EDID data sets. This parameter + allows to specify an EDID data set in the + /lib/firmware directory that is used instead. + Generic built-in EDID data sets are used, if one of + edid/1024x768.bin, edid/1280x1024.bin, + edid/1680x1050.bin, or edid/1920x1080.bin is given + and no file with the same name exists. Details and + instructions how to build your own EDID data are + available in Documentation/EDID/HOWTO.txt. An EDID + data set will only be used for a particular connector, + if its name and a colon are prepended to the EDID + name. + dscc4.setup= [NET] earlycon= [KNL] Output early console device and options.
drivers/gpu/drm/Kconfig +12 -0
@@ -27,6 +27,18 @@ config DRM_KMS_HELPER help FB and CRTC helpers for KMS drivers. +config DRM_LOAD_EDID_FIRMWARE + bool "Allow to specify an EDID data set instead of probing for it" + depends on DRM_KMS_HELPER + help + Say Y here, if you want to use EDID data to be loaded from the + /lib/firmware directory or one of the provided built-in + data sets. This may be necessary, if the graphics adapter or + monitor are unable to provide appropriate EDID data. Since this + feature is provided as a workaround for broken hardware, the + default case is N. Details and instructions how to build your own + EDID data are given in Documentation/EDID/HOWTO.txt. + config DRM_TTM tristate depends on DRM
drivers/gpu/drm/Makefile +3 -0
@@ -17,6 +17,9 @@ drm-y := drm_auth.o drm_buffer.o d drm-$(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
drivers/gpu/drm/drm_crtc_helper.c +7 -1
@@ -37,6 +37,7 @@#include "drm_fourcc.h" #include "drm_crtc_helper.h" #include "drm_fb_helper.h" +#include "drm_edid.h" static bool drm_kms_helper_poll = true;module_param_named (poll, drm_kms_helper_poll, bool,0600 );
@@ -118,7 +119,12 @@ int drm_helper_probe_single_connector_mo goto prune; } - count = (*connector_funcs->get_modes)(connector); +#ifdef CONFIG_DRM_LOAD_EDID_FIRMWARE + count =load_edid_firmware (connector); + if (count == 0) +#endif + count = (*connector_funcs->get_modes)(connector); +if (count ==0 && connector->status == connector_status_connected) count =drm_add_modes_noedid (connector,1024 ,768 );if (count ==0 )
drivers/gpu/drm/drm_edid.c +2 -2
@@ -149,8 +149,7 @@ EXPORT_SYMBOL(drm_edid_header_is_valid);* Sanity check the EDID block (base or extension). Return 0 if the block * doesn't check out, or 1 if it's valid. */ -static bool -drm_edid_block_valid (u8 *raw_edid) +bool drm_edid_block_valid (u8 *raw_edid) {int i;u8 csum =0 ;
@@ -203,6 +202,7 @@ bad: }return 0 ; } +EXPORT_SYMBOL (drm_edid_block_valid);/** * drm_edid_is_valid - sanity check EDID data
drivers/gpu/drm/drm_edid_load.c new file +250 -0
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include/drm/drm_crtc.h +1 -0
@@ -995,6 +995,7 @@ extern int drm_add_modes_noedid(struct d int hdisplay, int vdisplay);extern int drm_edid_header_is_valid (const u8 *raw_edid); +extern bool drm_edid_block_valid (u8 *raw_edid);extern bool drm_edid_is_valid (struct edid *edid);struct drm_display_mode *drm_mode_find_dmt (struct drm_device *dev,int hsize,int vsize,int fresh);
include/drm/drm_edid.h +1 -0
@@ -238,5 +238,6 @@ int drm_av_sync_delay(struct drm_connect struct drm_display_mode *mode);struct drm_connector *drm_select_eld (struct drm_encoder *encoder,struct drm_display_mode *mode); +int load_edid_firmware (struct drm_connector *connector);#endif /* __DRM_EDID_H__ */