drm/i915/fbdev: lock the fbdev obj before vma pin

lock the fbdev obj before calling into
i915_vma_pin_iomap(). This helps to solve below :

<7>[   93.563308] i915 0000:00:02.0: [drm:intelfb_create [i915]] no BIOS fb, allocating a new one
<4>[   93.581844] ------------[ cut here ]------------
<4>[   93.581855] WARNING: CPU: 12 PID: 625 at drivers/gpu/drm/i915/gem/i915_gem_pages.c:424 i915_gem_object_pin_map+0x152/0x1c0 [i915]

Fixes: f0b6b01 ("drm/i915: Add ww context to intel_dpt_pin, v2.")
Cc: Chris Wilson <[email protected]>
Cc: Matthew Auld <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Signed-off-by: Tejas Upadhyay <[email protected]>
Signed-off-by: Radhakrishna Sripada <[email protected]>
Reviewed-by: Andi Shyti <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 561b31a)
Signed-off-by: Jani Nikula <[email protected]>

Author: tejasup

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

@@ -210,6 +210,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
 	bool prealloc = false;
 	void __iomem *vaddr;
 	struct drm_i915_gem_object *obj;
+	struct i915_gem_ww_ctx ww;
 	int ret;
 
 	mutex_lock(&ifbdev->hpd_lock);
@@ -283,13 +284,24 @@ static int intelfb_create(struct drm_fb_helper *helper,
 		info->fix.smem_len = vma->size;
 	}
 
-	vaddr = i915_vma_pin_iomap(vma);
-	if (IS_ERR(vaddr)) {
-		drm_err(&dev_priv->drm,
-			"Failed to remap framebuffer into virtual memory (%pe)\n", vaddr);
-		ret = PTR_ERR(vaddr);
-		goto out_unpin;
+	for_i915_gem_ww(&ww, ret, false) {
+		ret = i915_gem_object_lock(vma->obj, &ww);
+
+		if (ret)
+			continue;
+
+		vaddr = i915_vma_pin_iomap(vma);
+		if (IS_ERR(vaddr)) {
+			drm_err(&dev_priv->drm,
+				"Failed to remap framebuffer into virtual memory (%pe)\n", vaddr);
+			ret = PTR_ERR(vaddr);
+			continue;
+		}
 	}
+
+	if (ret)
+		goto out_unpin;
+
 	info->screen_base = vaddr;
 	info->screen_size = vma->size;