[media] exynos4-is: Open shouldn't fail when sensor entity is not linked

In order to allow for automatic media device entities linking
from the level of libv4l plugin the open system call shouldn't
fail, as the libv4l plugins can begin their job not until it
succeeds.
This patch allows for leaving the  pipeline not linked on
open and postpones verifying it to the moment when streamon
callback is called.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/exynos4-is/media-dev.c

@@ -186,32 +186,20 @@ error:
 }
 
 /**
- * __fimc_pipeline_open - update the pipeline information, enable power
- *                        of all pipeline subdevs and the sensor clock
- * @me: media entity to start graph walk with
- * @prepare: true to walk the current pipeline and acquire all subdevs
+ * __fimc_pipeline_enable - enable power of all pipeline subdevs
+ *			    and the sensor clock
+ * @ep: video pipeline structure
+ * @fmd: fimc media device
  *
  * Called with the graph mutex held.
  */
-static int __fimc_pipeline_open(struct exynos_media_pipeline *ep,
-				struct media_entity *me, bool prepare)
+static int __fimc_pipeline_enable(struct exynos_media_pipeline *ep,
+				  struct fimc_md *fmd)
 {
-	struct fimc_md *fmd = entity_to_fimc_mdev(me);
 	struct fimc_pipeline *p = to_fimc_pipeline(ep);
-	struct v4l2_subdev *sd;
 	int ret;
 
-	if (WARN_ON(p == NULL || me == NULL))
-		return -EINVAL;
-
-	if (prepare)
-		fimc_pipeline_prepare(p, me);
-
-	sd = p->subdevs[IDX_SENSOR];
-	if (sd == NULL)
-		return -EINVAL;
-
-	/* Disable PXLASYNC clock if this pipeline includes FIMC-IS */
+	/* Enable PXLASYNC clock if this pipeline includes FIMC-IS */
 	if (!IS_ERR(fmd->wbclk[CLK_IDX_WB_B]) && p->subdevs[IDX_IS_ISP]) {
 		ret = clk_prepare_enable(fmd->wbclk[CLK_IDX_WB_B]);
 		if (ret < 0)
@@ -228,6 +216,40 @@ static int __fimc_pipeline_open(struct exynos_media_pipeline *ep,
 	return ret;
 }
 
+/**
+ * __fimc_pipeline_open - update the pipeline information, enable power
+ *                        of all pipeline subdevs and the sensor clock
+ * @me: media entity to start graph walk with
+ * @prepare: true to walk the current pipeline and acquire all subdevs
+ *
+ * Called with the graph mutex held.
+ */
+static int __fimc_pipeline_open(struct exynos_media_pipeline *ep,
+				struct media_entity *me, bool prepare)
+{
+	struct fimc_md *fmd = entity_to_fimc_mdev(me);
+	struct fimc_pipeline *p = to_fimc_pipeline(ep);
+	struct v4l2_subdev *sd;
+
+	if (WARN_ON(p == NULL || me == NULL))
+		return -EINVAL;
+
+	if (prepare)
+		fimc_pipeline_prepare(p, me);
+
+	sd = p->subdevs[IDX_SENSOR];
+	if (sd == NULL) {
+		pr_warn("%s(): No sensor subdev\n", __func__);
+		/*
+		 * Pipeline open cannot fail so as to make it possible
+		 * for the user space to configure the pipeline.
+		 */
+		return 0;
+	}
+
+	return __fimc_pipeline_enable(ep, fmd);
+}
+
 /**
  * __fimc_pipeline_close - disable the sensor clock and pipeline power
  * @fimc: fimc device terminating the pipeline
@@ -269,10 +291,43 @@ static int __fimc_pipeline_s_stream(struct exynos_media_pipeline *ep, bool on)
 		{ IDX_CSIS, IDX_FLITE, IDX_FIMC, IDX_SENSOR, IDX_IS_ISP },
 	};
 	struct fimc_pipeline *p = to_fimc_pipeline(ep);
+	struct fimc_md *fmd = entity_to_fimc_mdev(&p->subdevs[IDX_CSIS]->entity);
+	enum fimc_subdev_index sd_id;
 	int i, ret = 0;
 
-	if (p->subdevs[IDX_SENSOR] == NULL)
-		return -ENODEV;
+	if (p->subdevs[IDX_SENSOR] == NULL) {
+		if (!fmd->user_subdev_api) {
+			/*
+			 * Sensor must be already discovered if we
+			 * aren't in the user_subdev_api mode
+			 */
+			return -ENODEV;
+		}
+
+		/* Get pipeline sink entity */
+		if (p->subdevs[IDX_FIMC])
+			sd_id = IDX_FIMC;
+		else if (p->subdevs[IDX_IS_ISP])
+			sd_id = IDX_IS_ISP;
+		else if (p->subdevs[IDX_FLITE])
+			sd_id = IDX_FLITE;
+		else
+			return -ENODEV;
+
+		/*
+		 * Sensor could have been linked between open and STREAMON -
+		 * check if this is the case.
+		 */
+		fimc_pipeline_prepare(p, &p->subdevs[sd_id]->entity);
+
+		if (p->subdevs[IDX_SENSOR] == NULL)
+			return -ENODEV;
+
+		ret = __fimc_pipeline_enable(ep, fmd);
+		if (ret < 0)
+			return ret;
+
+	}
 
 	for (i = 0; i < IDX_MAX; i++) {
 		unsigned int idx = seq[on][i];
@@ -282,8 +337,10 @@ static int __fimc_pipeline_s_stream(struct exynos_media_pipeline *ep, bool on)
 		if (ret < 0 && ret != -ENOIOCTLCMD && ret != -ENODEV)
 			goto error;
 	}
+
 	return 0;
 error:
+	fimc_pipeline_s_power(p, !on);
 	for (; i >= 0; i--) {
 		unsigned int idx = seq[on][i];
 		v4l2_subdev_call(p->subdevs[idx], video, s_stream, !on);