drm/i915: Disregard drm_mode_config.fb_base

The fb_base is only used for communicating the GTT BAR from one piece of
the display code (kms setup) to another (fbdev). What is required in the
fbdev is just the aperture address which should be derived from the
bo we allocate for the framebuffer directly.

The same appears true for drm/; it is not used by the core or the uAPI,
it is merely for conveniently passing a device address from bit of
display management code to another.

v2: Note that since we only expose enough of a system map to cover our
single framebuffer, the screen_base/size and the smem are one and the
same.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813182112.23227-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/display/intel_display.c

@@ -16126,7 +16126,6 @@ static int intel_initial_commit(struct drm_device *dev)
 int intel_modeset_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
-	struct i915_ggtt *ggtt = &dev_priv->ggtt;
 	enum pipe pipe;
 	struct intel_crtc *crtc;
 	int ret;
@@ -16206,8 +16205,6 @@ int intel_modeset_init(struct drm_device *dev)
 		dev->mode_config.cursor_height = 256;
 	}
 
-	dev->mode_config.fb_base = ggtt->gmadr.start;
-
 	DRM_DEBUG_KMS("%d display pipe%s available.\n",
 		      INTEL_INFO(dev_priv)->num_pipes,
 		      INTEL_INFO(dev_priv)->num_pipes > 1 ? "s" : "");

drivers/gpu/drm/i915/display/intel_fbdev.c

@@ -241,12 +241,9 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	info->fbops = &intelfb_ops;
 
 	/* setup aperture base/size for vesafb takeover */
-	info->apertures->ranges[0].base = dev->mode_config.fb_base;
+	info->apertures->ranges[0].base = ggtt->gmadr.start;
 	info->apertures->ranges[0].size = ggtt->mappable_end;
 
-	info->fix.smem_start = dev->mode_config.fb_base + i915_ggtt_offset(vma);
-	info->fix.smem_len = vma->node.size;
-
 	vaddr = i915_vma_pin_iomap(vma);
 	if (IS_ERR(vaddr)) {
 		DRM_ERROR("Failed to remap framebuffer into virtual memory\n");
@@ -256,6 +253,10 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	info->screen_base = vaddr;
 	info->screen_size = vma->node.size;
 
+	/* Our framebuffer is the entirety of fbdev's system memory */
+	info->fix.smem_start = (unsigned long)info->screen_base;
+	info->fix.smem_len = info->screen_size;
+
 	drm_fb_helper_fill_info(info, &ifbdev->helper, sizes);
 
 	/* If the object is shmemfs backed, it will have given us zeroed pages.