drm/i915: Provide a command line option to disable display

If we can't actually determine at run-time we have a fused-off display,
provide at least an option to disable it.

v2: Move the i915.disable_display test in a separate check
    (Daniel Vetter)

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

3 files changed, 11 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 033c943b6bae..1d65dbd15c39 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1483,9 +1483,12 @@ static void intel_device_info_runtime_init(struct drm_device *dev)
         if (IS_VALLEYVIEW(dev))
                 info->num_sprites = 2;
 
-        if (info->num_pipes > 0 &&
-            (INTEL_INFO(dev)->gen == 7 || INTEL_INFO(dev)->gen == 8) &&
-            !IS_VALLEYVIEW(dev)) {
+        if (i915.disable_display) {
+                DRM_INFO("Display disabled (module parameter)\n");
+                info->num_pipes = 0;
+        } else if (info->num_pipes > 0 &&
+                   (INTEL_INFO(dev)->gen == 7 || INTEL_INFO(dev)->gen == 8) &&
+                   !IS_VALLEYVIEW(dev)) {
                 u32 fuse_strap = I915_READ(FUSE_STRAP);
                 u32 sfuse_strap = I915_READ(SFUSE_STRAP);
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 0580d979f88d..96601149cab8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1958,6 +1958,7 @@ struct i915_params {
         bool fastboot;
         bool prefault_disable;
         bool reset;
+        bool disable_display;
 };
 extern struct i915_params i915 __read_mostly;
 
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index c743057b6511..3b482585c5ae 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -47,6 +47,7 @@ struct i915_params i915 __read_mostly = {
         .prefault_disable = 0,
         .reset = true,
         .invert_brightness = 0,
+        .disable_display = 0,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -153,3 +154,6 @@ MODULE_PARM_DESC(invert_brightness,
         "report PCI device ID, subsystem vendor and subsystem device ID "
         "to dri-devel@lists.freedesktop.org, if your machine needs it. "
         "It will then be included in an upcoming module version.");
+
+module_param_named(disable_display, i915.disable_display, bool, 0600);
+MODULE_PARM_DESC(disable_display, "Disable display (default: false)");