[media] dvb-frontend: enable tuner link when the FE thread starts

If the dvb frontend thread starts, the tuner should be switched
to the frontend. Add a code that ensures that this will happen,
using the media controller.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

1 files changed, 94 insertions, 0 deletions

diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
index 2564422278df..50bc6056e914 100644
--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -590,12 +590,99 @@ static void dvb_frontend_wakeup(struct dvb_frontend *fe)
         wake_up_interruptible(&fepriv->wait_queue);
 }
 
+/**
+ * dvb_enable_media_tuner() - tries to enable the DVB tuner
+ *
+ * @fe:         struct dvb_frontend pointer
+ *
+ * This function ensures that just one media tuner is enabled for a given
+ * frontend. It has two different behaviors:
+ * - For trivial devices with just one tuner:
+ *   it just enables the existing tuner->fe link
+ * - For devices with more than one tuner:
+ *   It is up to the driver to implement the logic that will enable one tuner
+ *   and disable the other ones. However, if more than one tuner is enabled for
+ *   the same frontend, it will print an error message and return -EINVAL.
+ *
+ * At return, it will return the error code returned by media_entity_setup_link,
+ * or 0 if everything is OK, if no tuner is linked to the frontend or if the
+ * mdev is NULL.
+ */
+static int dvb_enable_media_tuner(struct dvb_frontend *fe)
+{
+#ifdef CONFIG_MEDIA_CONTROLLER_DVB
+        struct dvb_frontend_private *fepriv = fe->frontend_priv;
+        struct dvb_adapter *adapter = fe->dvb;
+        struct media_device *mdev = adapter->mdev;
+        struct media_entity  *entity, *source;
+        struct media_link *link, *found_link = NULL;
+        int i, ret, n_links = 0, active_links = 0;
+
+        if (!mdev)
+                return 0;
+
+        entity = fepriv->dvbdev->entity;
+        for (i = 0; i < entity->num_links; i++) {
+                link = &entity->links[i];
+                if (link->sink->entity == entity) {
+                        found_link = link;
+                        n_links++;
+                        if (link->flags & MEDIA_LNK_FL_ENABLED)
+                                active_links++;
+                }
+        }
+
+        if (!n_links || active_links == 1 || !found_link)
+                return 0;
+
+        /*
+         * If a frontend has more than one tuner linked, it is up to the driver
+         * to select with one will be the active one, as the frontend core can't
+         * guess. If the driver doesn't do that, it is a bug.
+         */
+        if (n_links > 1 && active_links != 1) {
+                dev_err(fe->dvb->device,
+                        "WARNING: there are %d active links among %d tuners. This is a driver's bug!\n",
+                        active_links, n_links);
+                return -EINVAL;
+        }
+
+        source = found_link->source->entity;
+        for (i = 0; i < source->num_links; i++) {
+                struct media_entity *sink;
+                int flags = 0;
+
+                link = &source->links[i];
+                sink = link->sink->entity;
+
+                if (sink == entity)
+                        flags = MEDIA_LNK_FL_ENABLED;
+
+                ret = media_entity_setup_link(link, flags);
+                if (ret) {
+                        dev_err(fe->dvb->device,
+                                "Couldn't change link %s->%s to %s. Error %d\n",
+                                source->name, sink->name,
+                                flags ? "enabled" : "disabled",
+                                ret);
+                        return ret;
+                } else
+                        dev_dbg(fe->dvb->device,
+                                "link %s->%s was %s\n",
+                                source->name, sink->name,
+                                flags ? "ENABLED" : "disabled");
+        }
+#endif
+        return 0;
+}
+
 static int dvb_frontend_thread(void *data)
 {
         struct dvb_frontend *fe = data;
         struct dvb_frontend_private *fepriv = fe->frontend_priv;
         fe_status_t s;
         enum dvbfe_algo algo;
+        int ret;
 
         bool re_tune = false;
         bool semheld = false;
@@ -609,6 +696,13 @@ static int dvb_frontend_thread(void *data)
         fepriv->wakeup = 0;
         fepriv->reinitialise = 0;
 
+        ret = dvb_enable_media_tuner(fe);
+        if (ret) {
+                /* FIXME: return an error if it fails */
+                dev_info(fe->dvb->device,
+                        "proceeding with FE task\n");
+        }
+
         dvb_frontend_init(fe);
 
         set_freezable();