Fixed synchronisation problem where an app could issue

FE_SET_FRONTEND, but start reading data before the frontend was
actually set. This caused some really confusing errors.

1 files changed, 21 insertions, 10 deletions

diff --git a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c b/linux/drivers/media/dvb/dvb-core/dvb_frontend.c
index cffbed5a5..aab5d41bc 100644
--- a/linux/drivers/media/dvb/dvb-core/dvb_frontend.c
+++ b/linux/drivers/media/dvb/dvb-core/dvb_frontend.c
@@ -547,19 +547,17 @@ static int dvb_frontend_thread (void *data)
 		        continue;
 		}
 	   
-	        // if we're in the RETUNE state, move immediately to the ZIGZAG_FAST state
-		// and, if we're sitting comfortably, begin
+	        // if we're in the RETUNE state, set everything up for a brand new scan
 	        if (fe->state & FESTATE_RETUNE) {
 		        fe->lnb_drift = 0;
 		        fe->inversion = INVERSION_OFF;
 		        fe->auto_count = 0;
 		        fe->started_auto_count = 0;
-		        fe->state = FESTATE_TUNING_FAST;
 		        clean_setup_count = 0;
 		}
 	    
-	        // fast zigzag
-		if (fe->state & FESTATE_SEARCHING_FAST) {
+	        // fast zigzag.
+		if ((fe->state & FESTATE_SEARCHING_FAST) || (fe->state & FESTATE_RETUNE)) {
 		        delay = fe->min_delay;
 		   
 		        // OK, if we've run out of trials at the fast speed. Drop back to
@@ -574,6 +572,12 @@ static int dvb_frontend_thread (void *data)
 		        if ((!(fe->info->caps & FE_CAN_CLEAN_SETUP)) && (clean_setup_count == 0)) {
 			        fe->state = FESTATE_CLEAN_SETUP;
 			}
+		    
+		        // if we've just retuned, enter the ZIGZAG_FAST state. This ensures
+			// we cannot return from an FE_SET_FRONTEND before the retune occurs.
+			if (fe->state & FESTATE_RETUNE) {
+			        fe->state = FESTATE_TUNING_FAST;
+			}
 		}
 
 	        // slow zigzag
@@ -744,14 +748,21 @@ static int dvb_frontend_ioctl (struct inode *inode, struct file *file,
 	default:
 		dvb_frontend_internal_ioctl (&fe->frontend, cmd, parg);
 	};
-      
-        // Force the CAN_INVERSION_AUTO bit on
-	if (cmd == FE_GET_INFO) {
+    
+	up (&fe->sem);
+
+        // Force the CAN_INVERSION_AUTO bit on. If the frontend doesn't do it, it is done for it.
+	if ((cmd == FE_GET_INFO) && (err == 0)) {
 	        struct dvb_frontend_info* tmp = (struct dvb_frontend_info*) parg;
 	        tmp->caps |= FE_CAN_INVERSION_AUTO;
 	}
-    
-	up (&fe->sem);
+
+        // if the frontend has just been set, wait until the first tune has finished.
+	// This ensures the app doesn't start reading data too quickly, perhaps from the
+	// previous lock, which is REALLY CONFUSING TO DEBUG!
+	if ((cmd == FE_SET_FRONTEND) && (err == 0)) {
+	        err = wait_event_interruptible(fe->wait_queue, fe->state == FESTATE_RETUNE);
+	}
 
 	return err;
 }