Some recent integrated graphics chipset, notably Intel's "Pineview", also
provide on-chip LVDS support. As an extra service, the LVDS interface supplies
EDID data - irrespective of whether an LVDS panel is connected or not. The
drm_mode_getresources() function, therefore, causes Xorg to always include
the LVDS panel into the display and initialize a separate screen for it. e.g.
(II) intel(0): Output LVDS1 connected
(II) intel(0): Output VGA1 connected
(II) intel(0): Using spanning desktop for initial modes
(II) intel(0): Output LVDS1 using initial mode 1024x768 +0+0
(II) intel(0): Output VGA1 using initial mode 1280x1024 +1024+0
which is not what you want, if the only connected screen is a VGA monitor.
One would assume that the BIOS settings of such systems would allow to
separately enable or disable LVDS support; unfortunately, systems have been
found in the wild that do not provide this feature.
This patch introduces the module parameter "disable_connector" of the
drm_kms_helper module that may specify the name of the connector to be
considered disabled, e.g.
# cat /etc/modprobe.d/drm_kms_helper.conf
options drm_kms_helper disable_connector=LVDS-1
which lets Xorg correctly initialize the screen, e.g.
(II) intel(0): Output LVDS1 disconnected
(II) intel(0): Output VGA1 connected
(II) intel(0): Using exact sizes for initial modes
(II) intel(0): Output VGA1 using initial mode 1280x1024 +0+0
A second scenario applies to broken graphics adapters that are unable to
correctly detect connected monitors and end up in a situation where
the default screen resolution of 1024x768 is selected that may not be
appropriate, e.g.
(II) intel(0): Output VGA1 disconnected
(II) intel(0): Output HDMI1 disconnected
(II) intel(0): Output DP1 disconnected
(II) intel(0): Output HDMI2 disconnected
(II) intel(0): Output DP2 disconnected
(WW) intel(0): No outputs definitely connected, trying again...
(II) intel(0): Output VGA1 disconnected
(II) intel(0): Output HDMI1 disconnected
(II) intel(0): Output DP1 disconnected
(II) intel(0): Output HDMI2 disconnected
(II) intel(0): Output DP2 disconnected
(WW) intel(0): Unable to find connected outputs - setting 1024x768 initial framebuffer
This patch introduces a second module parameter "enable_connector" of the
drm_kms_helper module that may specify the name of the connector to be
taken as connected, e.g.
# cat /etc/modprobe.d/drm_kms_helper.conf
options drm_kms_helper enable_connector=VGA-1
which lets Xorg correctly initialize the screen, e.g.
(II) intel(0): Output VGA1 connected
(II) intel(0): Output HDMI1 disconnected
(II) intel(0): Output DP1 disconnected
(II) intel(0): Output HDMI2 disconnected
(II) intel(0): Output DP2 disconnected
(II) intel(0): Using exact sizes for initial modes
(II) intel(0): Output VGA1 using initial mode 1280x1024 +0+0
Signed-off-by: Carsten Emde <C.Emde@xxxxxxxxx>
---
Documentation/kernel-parameters.txt | 13 ++++++++++++
drivers/gpu/drm/drm_crtc.c | 15 ++++++++++---
drivers/gpu/drm/drm_crtc_helper.c | 3 ++
drivers/gpu/drm/drm_fb_helper.c | 39 ++++++++++++++++++++++++++++++++++--
include/drm/drm_crtc.h | 3 +-
5 files changed, 66 insertions(+), 7 deletions(-)
Index: linux-3.3-rc6/Documentation/kernel-parameters.txt
===================================================================
--- linux-3.3-rc6.orig/Documentation/kernel-parameters.txt
+++ linux-3.3-rc6/Documentation/kernel-parameters.txt
@@ -713,12 +713,25 @@ bytes respectively. Such letter suffixes
The filter can be disabled or changed to another
driver later using sysfs.
+ drm_kms_helper.disable_connector=<connector>
+ The BIOS may always report that a panel is connected,
+ irrespective of whether it really is or not which may
+ lead to a bogus screen layout. This parameter is used
+ to explicitly disable a particular connector, e.g.
+ drm_kms_helper disable_connector=LVDS-1
+
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.
+ drm_kms_helper.enable_connector=<connector>
+ Broken hardware may be unable to correctly discover a
+ monitor. This parameter is used to let the drm subsystem
+ assume that a monitor is present at the specified
+ connector, e.g. drm_kms_helper enable_connector=VGA-1
+
dscc4.setup= [NET]
earlycon= [KNL] Output early console device and options.
Index: linux-3.3-rc6/drivers/gpu/drm/drm_crtc.c
===================================================================
--- linux-3.3-rc6.orig/drivers/gpu/drm/drm_crtc.c
+++ linux-3.3-rc6/drivers/gpu/drm/drm_crtc.c
@@ -204,6 +204,8 @@ char *drm_get_connector_status_name(enum
return "connected";
else if (status == connector_status_disconnected)
return "disconnected";
+ else if (status == connector_status_disabled)
+ return "disabled";
else
return "unknown";
}
@@ -1172,8 +1174,11 @@ int drm_mode_getresources(struct drm_dev
list_for_each(lh, &dev->mode_config.crtc_list)
crtc_count++;
- list_for_each(lh, &dev->mode_config.connector_list)
- connector_count++;
+ list_for_each_entry(connector,
+ &dev->mode_config.connector_list, head)
+ if (connector->status != connector_status_disabled)
+ connector_count++;
+
list_for_each(lh, &dev->mode_config.encoder_list)
encoder_count++;
@@ -1268,8 +1273,10 @@ int drm_mode_getresources(struct drm_dev
connector_id = (uint32_t __user *)(unsigned long)card_res->connector_id_ptr;
if (file_priv->master->minor->type == DRM_MINOR_CONTROL) {
list_for_each_entry(connector,
- &dev->mode_config.connector_list,
- head) {
+ &dev->mode_config.connector_list, head) {
+ if (connector->status ==
+ connector_status_disabled)
+ continue;
DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
connector->base.id,
drm_get_connector_name(connector));
Index: linux-3.3-rc6/drivers/gpu/drm/drm_crtc_helper.c
===================================================================
--- linux-3.3-rc6.orig/drivers/gpu/drm/drm_crtc_helper.c
+++ linux-3.3-rc6/drivers/gpu/drm/drm_crtc_helper.c
@@ -119,6 +119,9 @@ int drm_helper_probe_single_connector_mo
goto prune;
}
+ if (connector->status == connector_status_disabled)
+ return 0;
+
#ifdef CONFIG_DRM_LOAD_EDID_FIRMWARE
count = load_edid_firmware(connector);
if (count == 0)
Index: linux-3.3-rc6/drivers/gpu/drm/drm_fb_helper.c
===================================================================
--- linux-3.3-rc6.orig/drivers/gpu/drm/drm_fb_helper.c
+++ linux-3.3-rc6/drivers/gpu/drm/drm_fb_helper.c
@@ -28,6 +28,7 @@
* Jesse Barnes <jesse.barnes@xxxxxxxxx>
*/
#include <linux/kernel.h>
+#include <linux/module.h>
#include <linux/sysrq.h>
#include <linux/slab.h>
#include <linux/fb.h>
@@ -1056,6 +1057,9 @@ static bool drm_connector_enabled(struct
{
bool enable;
+ if (connector->status == connector_status_disabled)
+ return false;
+
if (strict) {
enable = connector->status == connector_status_connected;
} else {
@@ -1064,6 +1068,16 @@ static bool drm_connector_enabled(struct
return enable;
}
+static char disable_connector[32];
+module_param_string(disable_connector, disable_connector,
+ sizeof(disable_connector), 0644);
+MODULE_PARM_DESC(disable_connector,
+ "Do not use specified connector, even if monitor detected");
+static char enable_connector[32];
+module_param_string(enable_connector, enable_connector,
+ sizeof(enable_connector), 0644);
+MODULE_PARM_DESC(enable_connector,
+ "Use specified connector, even if no monitor connected");
static void drm_enable_connectors(struct drm_fb_helper *fb_helper,
bool *enabled)
{
@@ -1072,10 +1086,31 @@ static void drm_enable_connectors(struct
int i = 0;
for (i = 0; i < fb_helper->connector_count; i++) {
+ char *connector_name;
+
connector = fb_helper->connector_info[i]->connector;
+ connector_name = drm_get_connector_name(connector);
+
+ if (connector_name == NULL)
+ continue;
+ if (disable_connector[0] != '\0' &&
+ !strcmp(connector_name, disable_connector)) {
+ connector->status = connector_status_disabled;
+ DRM_DEBUG_KMS("connector %d (\"%s\") disabled "
+ "by module parameter\n", connector->base.id,
+ connector_name);
+ }
+ if (enable_connector[0] != '\0' &&
+ !strcmp(connector_name, enable_connector)) {
+ connector->status = connector_status_connected;
+ DRM_DEBUG_KMS("connector %d (\"%s\") enabled "
+ "by module parameter\n", connector->base.id,
+ connector_name);
+ }
enabled[i] = drm_connector_enabled(connector, true);
- DRM_DEBUG_KMS("connector %d enabled? %s\n", connector->base.id,
- enabled[i] ? "yes" : "no");
+ DRM_DEBUG_KMS("connector %d (\"%s\") enabled? %s\n",
+ connector->base.id, connector_name,
+ enabled[i] ? "yes" : "no");
any_enabled |= enabled[i];
}
Index: linux-3.3-rc6/include/drm/drm_crtc.h
===================================================================
--- linux-3.3-rc6.orig/include/drm/drm_crtc.h
+++ linux-3.3-rc6/include/drm/drm_crtc.h
@@ -172,7 +172,8 @@ struct drm_display_mode {
enum drm_connector_status {
connector_status_connected = 1,
connector_status_disconnected = 2,
- connector_status_unknown = 3,
+ connector_status_disabled = 3,
+ connector_status_unknown = 4,
};
enum subpixel_order {
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