V4L/DVB (12269): af9013: auto-detect parameters in case of garbage given by app

Request demodulator auto-detect transmission parameters in case of
garbage parameters provided by application for compatibility.
That's needed at least for MPlayer compatibility currently.

Thanks to Jelle de Jong for reporting issue and providing SSH access to
Devin for debugging.

Thanks to Devin Heitmueller for hard debug work he did to find that bug.

Cc: Devin Heitmueller <[e-mail]>
Cc: Jelle de Jong <[e-mail]>
Signed-off-by: Antti Palosaari <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb/frontends/af9013.c

···
 	u8 i, buf[3] = {0, 0, 0};
 	*auto_mode = 0; /* set if parameters are requested to auto set */
 
+	/* Try auto-detect transmission parameters in case of AUTO requested or
+	   garbage parameters given by application for compatibility.
+	   MPlayer seems to provide garbage parameters currently. */
+
 	switch (params->transmission_mode) {
 	case TRANSMISSION_MODE_AUTO:
 		*auto_mode = 1;
···
 		buf[0] |= (1 << 0);
 		break;
 	default:
-		return -EINVAL;
+		deb_info("%s: invalid transmission_mode\n", __func__);
+		*auto_mode = 1;
 	}
 
 	switch (params->guard_interval) {
···
 		buf[0] |= (3 << 2);
 		break;
 	default:
-		return -EINVAL;
+		deb_info("%s: invalid guard_interval\n", __func__);
+		*auto_mode = 1;
 	}
 
 	switch (params->hierarchy_information) {
···
 		buf[0] |= (3 << 4);
 		break;
 	default:
-		return -EINVAL;
+		deb_info("%s: invalid hierarchy_information\n", __func__);
+		*auto_mode = 1;
 	};
 
 	switch (params->constellation) {
···
 		buf[1] |= (2 << 6);
 		break;
 	default:
-		return -EINVAL;
+		deb_info("%s: invalid constellation\n", __func__);
+		*auto_mode = 1;
 	}
 
 	/* Use HP. How and which case we can switch to LP? */
···
 		buf[2] |= (4 << 0);
 		break;
 	default:
-		return -EINVAL;
+		deb_info("%s: invalid code_rate_HP\n", __func__);
+		*auto_mode = 1;
 	}
 
 	switch (params->code_rate_LP) {
···
 		if (params->hierarchy_information == HIERARCHY_AUTO)
 			break;
 	default:
-		return -EINVAL;
+		deb_info("%s: invalid code_rate_LP\n", __func__);
+		*auto_mode = 1;
 	}
 
 	switch (params->bandwidth) {
···
 		buf[1] |= (2 << 2);
 		break;
 	default:
-		return -EINVAL;
+		deb_info("%s: invalid bandwidth\n", __func__);
+		buf[1] |= (2 << 2); /* cannot auto-detect BW, try 8 MHz */
 	}
 
 	/* program */