staging: imx-drm: Fix probe failure

Since commit b5dc0d10 (drm/imx: kill firstopen callback) the following probe
failure is seen:

[drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
[drm] No driver support for vblank timestamp query.
[drm] Initialized imx-drm 1.0.0 20120507 on minor 0
imx-ldb ldb.10: adding encoder failed with -16
imx-ldb: probe of ldb.10 failed with error -16
imx-ipuv3 2400000.ipu: IPUv3H probed
imx-ipuv3 2800000.ipu: IPUv3H probed
imx-ipuv3-crtc imx-ipuv3-crtc.0: adding crtc failed with -16.
imx-ipuv3-crtc: probe of imx-ipuv3-crtc.0 failed with error -16
imx-ipuv3-crtc imx-ipuv3-crtc.1: adding crtc failed with -16.
imx-ipuv3-crtc: probe of imx-ipuv3-crtc.1 failed with error -16
imx-ipuv3-crtc imx-ipuv3-crtc.2: adding crtc failed with -16.
imx-ipuv3-crtc: probe of imx-ipuv3-crtc.2 failed with error -16
imx-ipuv3-crtc imx-ipuv3-crtc.3: adding crtc failed with -16.
imx-ipuv3-crtc: probe of imx-ipuv3-crtc.3 failed with error -16

The reason for the probe failure is that now 'imxdrm->references' is incremented
early in imx_drm_driver_load(), so the following checks in imx_drm_add_crtc()
and imx_drm_add_encoder():

	if (imxdrm->references) {
		ret = -EBUSY;
		goto err_busy;
	}

,will always fail.

Instead of manually keeping the references in the imx-drm driver, let's use
drm->open_count.

After this patch, lvds panel is functional on a mx6qsabrelite board.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 8 deletions

diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c
index 47c5888461ff..a2e52a0c53c9 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -41,7 +41,6 @@ struct imx_drm_device {
         struct list_head                        encoder_list;
         struct list_head                        connector_list;
         struct mutex                            mutex;
-        int                                     references;
         int                                     pipes;
         struct drm_fbdev_cma                    *fbhelper;
 };
@@ -241,8 +240,6 @@ struct drm_device *imx_drm_device_get(void)
                 }
         }
 
-        imxdrm->references++;
-
         return imxdrm->drm;
 
 unwind_crtc:
@@ -280,8 +277,6 @@ void imx_drm_device_put(void)
         list_for_each_entry(enc, &imxdrm->encoder_list, list)
                 module_put(enc->owner);
 
-        imxdrm->references--;
-
         mutex_unlock(&imxdrm->mutex);
 }
 EXPORT_SYMBOL_GPL(imx_drm_device_put);
@@ -485,7 +480,7 @@ int imx_drm_add_crtc(struct drm_crtc *crtc,
 
         mutex_lock(&imxdrm->mutex);
 
-        if (imxdrm->references) {
+        if (imxdrm->drm->open_count) {
                 ret = -EBUSY;
                 goto err_busy;
         }
@@ -564,7 +559,7 @@ int imx_drm_add_encoder(struct drm_encoder *encoder,
 
         mutex_lock(&imxdrm->mutex);
 
-        if (imxdrm->references) {
+        if (imxdrm->drm->open_count) {
                 ret = -EBUSY;
                 goto err_busy;
         }
@@ -709,7 +704,7 @@ int imx_drm_add_connector(struct drm_connector *connector,
 
         mutex_lock(&imxdrm->mutex);
 
-        if (imxdrm->references) {
+        if (imxdrm->drm->open_count) {
                 ret = -EBUSY;
                 goto err_busy;
         }