Provide workarounds to use DRM/KMS with broken graphics hardware

Einfaches Textdokument-Anlage (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

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 also 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 <[email protected]>

---
 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         |   25 +++
 Documentation/EDID/edid.S           |  261 ++++++++++++++++++++++++++++++++++++
 Documentation/EDID/hex              |    1 
 Documentation/kernel-parameters.txt |   10 +
 drivers/gpu/drm/Kconfig             |   11 +
 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     |  241 +++++++++++++++++++++++++++++++++
 include/drm/drm_crtc.h              |    1 
 include/drm/drm_edid.h              |    1 
 16 files changed, 778 insertions(+), 3 deletions(-)

Index: linux-3.3-rc6/Documentation/kernel-parameters.txt
===================================================================

Documentation/kernel-parameters.txt +0 -0

@@ -713,6 +713,16 @@ bytes respectively. Such letter suffixes
 			The filter can be disabled or changed to another
 			driver later using sysfs.

Documentation/kernel-parameters.txt +1 -0

+
 	dscc4.setup=	[NET]
 
 	earlycon=	[KNL] Output early console device and options.

Index: linux-3.3-rc6/drivers/gpu/drm/Kconfig
===================================================================

drivers/gpu/drm/Kconfig +0 -0

@@ -27,6 +27,17 @@ config DRM_KMS_HELPER
 	help
 	  FB and CRTC helpers for KMS drivers.
 

Dear Carsten,

Am Donnerstag, den 15.03.2012, 00:35 +0100 schrieb Carsten Emde:

Quoted 2 lines

Einfaches Textdokument-Anlage (drivers-gpu-drm-allow-to-load-edid-firmware.patch)

somehow your message was send as an attachment. Could you configure your mailer (quilt) that it is send inline?

Quoted 7 lines

Am Donnerstag, den 15.03.2012, 00:35 +0100 schrieb Carsten Emde:

Quoted 2 lines

Einfaches Textdokument-Anlage (drivers-gpu-drm-allow-to-load-edid-firmware.patch)

somehow your message was send as an attachment. Could you configure your mailer (quilt) that it is send inline?

quilt sends the patches inline. From Carstens original mail:

Content-Disposition: inline; filename=drivers-gpu-drm-allow-to-load-edid-firmware.patch

Could you use a sane mail client or teach Devolution to stop being silly?

Am Donnerstag, den 15.03.2012, 11:08 +0100 schrieb Thomas Gleixner:

Quoted 11 lines · Paul Menzel

Quoted 7 lines

Am Donnerstag, den 15.03.2012, 00:35 +0100 schrieb Carsten Emde:

Quoted 2 lines

Einfaches Textdokument-Anlage (drivers-gpu-drm-allow-to-load-edid-firmware.patch)

somehow your message was send as an attachment. Could you configure your mailer (quilt) that it is send inline?

quilt sends the patches inline. From Carstens original mail:

Quoted 4 lines

Content-Disposition: inline; filename=drivers-gpu-drm-allow-to-load-edid-firmware.patch

Could you use a sane mail client or teach Devolution to stop being silly?

Actually Evolution displayed the message inline. Only when replying the attachment message was added to the top.

Still that leaves the ugly subject line in my opinion, where quilt only seems to use the file name.

This patch adds a module parameter to invert the backlight brightness value before writing and after reading which makes the affected notebook usable again.

<#part sign=pgpmime>

Quoted 4 lines

This patch adds a module parameter to invert the backlight brightness value before writing and after reading which makes the affected notebook usable again.

You should add a quirk for this and set things up so that your machine automatically gets the right value; when we find more machines that do this, we can add them so that more people will get a system that 'just works'.

Einfaches Textdokument-Anlage (drivers-gpu-drm-i915-invert-backlight-brightness.patch)

Following the documentation of the Legacy Backlight Brightness (LBB) Register in the configuration space of some Intel PCI graphics adapters, setting the LBB register with the value 0x0 causes the backlight to be turned off, and 0xFF causes the backlight to be set to 100% intensity
(http://download.intel.com/embedded/processors/Whitepaper/324567.pdf).
At least one of our test systems, however, turns the backlight off at 0xFF and sets it to maximum intensity at 0. In consequence, the screen of this systems becomes dark at an early boot stage which makes it unusable. The same inversion applies to the BLC_PWM_CTL I915 register. This problem was introduced in kernel version 2.6.38 when the PCI device of this system was first supported by the i915 KMS module.

This patch adds a module parameter to invert the backlight brightness value before writing and after reading which makes the affected notebook usable again.

Signed-off-by Carsten Emde <[email protected]>

---
 Documentation/kernel-parameters.txt |    9 +++++++++
 drivers/gpu/drm/i915/intel_panel.c  |   14 ++++++++++++++
 2 files changed, 23 insertions(+)

Index: linux-3.3-rc6/Documentation/kernel-parameters.txt
===================================================================

Documentation/kernel-parameters.txt +9 -0

@@ -966,6 +966,15 @@ bytes respectively. Such letter suffixes
 
 	i810=		[HW,DRM]
 
+	i915.invert_brightness
+			[DRM] Invert the sense of the variable that is used to
+			set the brightness of the panel backlight. Normally a
+			value of 0 indicates backlight switched off, and the
+			maximum value sets the backlight to maximum brightness.
+			If this parameter is specified, a value of 0 sets the
+			backlight to maximum brightness, and the maximum value
+			switches the backlight off.
+
 	i8k.ignore_dmi	[HW] Continue probing hardware even if DMI data
 			indicates that the driver is running on unsupported
 			hardware.

Index: linux-3.3-rc6/drivers/gpu/drm/i915/intel_panel.c
===================================================================

drivers/gpu/drm/i915/intel_panel.c +1 -0

@@ -28,6 +28,7 @@
  *      Chris Wilson <[email protected]>
  */
 
+#include <linux/moduleparam.h>
 #include "intel_drv.h"
 
 #define PCI_LBPC 0xf4 /* legacy/combination backlight modes */

drivers/gpu/drm/i915/intel_panel.c +5 -0

+module_param_named(brightness_inverted, brightness_inverted, bool, 0600);
 u32 intel_panel_get_backlight(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;

@@ -212,6 +217,10 @@ u32 intel_panel_get_backlight(struct drm
 	}
 
 	DRM_DEBUG_DRIVER("get backlight PWM = %d\n", val);
+	if (brightness_inverted) {
+		u32 max = intel_panel_get_max_backlight(dev);
+		val = max - val;
+	}
 	return val;
 }