drm: Rely on mode_config data for fb_helper initialization

Instead of receiving the num_crts as a parameter, we can read it
directly from the mode_config structure.  I audited the drivers that
invoke this helper and I believe all of them initialize the mode_config
struct accordingly, prior to calling the fb_helper.

I used the following coccinelle hack to make this transformation, except
for the function headers and comment updates.  The first and second
rules are split because I couldn't find a way to remove the unused
temporary variables at the same time I removed the parameter.

// <smpl>
@r@
expression A,B,D,E;
identifier C;
@@
(
- drm_fb_helper_init(A,B,C,D)
+ drm_fb_helper_init(A,B,D)
|
- drm_fbdev_cma_init_with_funcs(A,B,C,D,E)
+ drm_fbdev_cma_init_with_funcs(A,B,D,E)
|
- drm_fbdev_cma_init(A,B,C,D)
+ drm_fbdev_cma_init(A,B,D)
)

@@
expression A,B,C,D,E;
@@
(
- drm_fb_helper_init(A,B,C,D)
+ drm_fb_helper_init(A,B,D)
|
- drm_fbdev_cma_init_with_funcs(A,B,C,D,E)
+ drm_fbdev_cma_init_with_funcs(A,B,D,E)
|
- drm_fbdev_cma_init(A,B,C,D)
+ drm_fbdev_cma_init(A,B,D)
)

@@
identifier r.C;
type T;
expression V;
@@
- T C;
<...
when != C
- C = V;
...>
// </smpl>

Changes since v1:
 - Rebased on top of the tip of drm-misc-next.
 - Remove mention to sti since a proper fix got merged.

Suggested-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170202162640.27261-1-krisman@collabora.co.uk

drivers/gpu/drm/drm_fb_cma_helper.c

@@ -489,15 +489,14 @@ static const struct drm_fb_helper_funcs drm_fb_cma_helper_funcs = {
  * drm_fbdev_cma_init_with_funcs() - Allocate and initializes a drm_fbdev_cma struct
  * @dev: DRM device
  * @preferred_bpp: Preferred bits per pixel for the device
- * @num_crtc: Number of CRTCs
  * @max_conn_count: Maximum number of connectors
  * @funcs: fb helper functions, in particular a custom dirty() callback
  *
  * Returns a newly allocated drm_fbdev_cma struct or a ERR_PTR.
  */
 struct drm_fbdev_cma *drm_fbdev_cma_init_with_funcs(struct drm_device *dev,
-	unsigned int preferred_bpp, unsigned int num_crtc,
-	unsigned int max_conn_count, const struct drm_framebuffer_funcs *funcs)
+	unsigned int preferred_bpp, unsigned int max_conn_count,
+	const struct drm_framebuffer_funcs *funcs)
 {
 	struct drm_fbdev_cma *fbdev_cma;
 	struct drm_fb_helper *helper;
@@ -514,7 +513,7 @@ struct drm_fbdev_cma *drm_fbdev_cma_init_with_funcs(struct drm_device *dev,
 
 	drm_fb_helper_prepare(dev, helper, &drm_fb_cma_helper_funcs);
 
-	ret = drm_fb_helper_init(dev, helper, num_crtc, max_conn_count);
+	ret = drm_fb_helper_init(dev, helper, max_conn_count);
 	if (ret < 0) {
 		dev_err(dev->dev, "Failed to initialize drm fb helper.\n");
 		goto err_free;
@@ -554,11 +553,11 @@ EXPORT_SYMBOL_GPL(drm_fbdev_cma_init_with_funcs);
  * Returns a newly allocated drm_fbdev_cma struct or a ERR_PTR.
  */
 struct drm_fbdev_cma *drm_fbdev_cma_init(struct drm_device *dev,
-	unsigned int preferred_bpp, unsigned int num_crtc,
-	unsigned int max_conn_count)
+	unsigned int preferred_bpp, unsigned int max_conn_count)
 {
-	return drm_fbdev_cma_init_with_funcs(dev, preferred_bpp, num_crtc,
-				max_conn_count, &drm_fb_cma_funcs);
+	return drm_fbdev_cma_init_with_funcs(dev, preferred_bpp,
+					     max_conn_count,
+					     &drm_fb_cma_funcs);
 }
 EXPORT_SYMBOL_GPL(drm_fbdev_cma_init);