V4L/DVB (5174): Pvrusb2: video corruption fixes

Tweak the encoder setup in order to stop it from corrupting the video
data when there is a disruption in the data flow (e.g. a channel change).
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/pvrusb2/pvrusb2-encoder.c

@@ -321,6 +321,73 @@ static int pvr2_encoder_vcmd(struct pvr2_hdw *hdw, int cmd,
 	return pvr2_encoder_cmd(hdw,cmd,args,0,data);
 }
 
+
+/* This implements some extra setup for the encoder that seems to be
+   specific to the PVR USB2 hardware. */
+int pvr2_encoder_prep_config(struct pvr2_hdw *hdw)
+{
+	int ret = 0;
+	int encMisc3Arg = 0;
+
+#if 0
+	/* This inexplicable bit happens in the Hauppage windows
+	   driver (for both 24xxx and 29xxx devices).  However I
+	   currently see no difference in behavior with or without
+	   this stuff.  Leave this here as a note of its existence,
+	   but don't use it. */
+	LOCK_TAKE(hdw->ctl_lock); do {
+		u32 dat[1];
+		dat[0] = 0x80000640;
+		pvr2_encoder_write_words(hdw,0x01fe,dat,1);
+		pvr2_encoder_write_words(hdw,0x023e,dat,1);
+	} while(0); LOCK_GIVE(hdw->ctl_lock);
+#endif
+
+	/* Mike Isely <isely@pobox.com> 26-Jan-2006 The windows driver
+	   sends the following list of ENC_MISC commands (for both
+	   24xxx and 29xxx devices).  Meanings are not entirely clear,
+	   however without the ENC_MISC(3,1) command then we risk
+	   random perpetual video corruption whenever the video input
+	   breaks up for a moment (like when switching channels). */
+
+
+#if 0
+	/* This ENC_MISC(5,0) command seems to hurt 29xxx sync
+	   performance on channel changes, but is not a problem on
+	   24xxx devices. */
+	ret |= pvr2_encoder_vcmd(hdw, CX2341X_ENC_MISC,4, 5,0,0,0);
+#endif
+
+	/* This ENC_MISC(3,encMisc3Arg) command is critical - without
+	   it there will eventually be video corruption.  Also, the
+	   29xxx case is strange - the Windows driver is passing 1
+	   regardless of device type but if we have 1 for 29xxx device
+	   the video turns sluggish.  */
+	switch (hdw->hdw_type) {
+	case PVR2_HDW_TYPE_24XXX: encMisc3Arg = 1; break;
+	case PVR2_HDW_TYPE_29XXX: encMisc3Arg = 0; break;
+	default: break;
+	}
+	ret |= pvr2_encoder_vcmd(hdw, CX2341X_ENC_MISC,4, 3,
+				 encMisc3Arg,0,0);
+
+	ret |= pvr2_encoder_vcmd(hdw, CX2341X_ENC_MISC,4, 8,0,0,0);
+
+#if 0
+	/* This ENC_MISC(4,1) command is poisonous, so it is commented
+	   out.  But I'm leaving it here anyway to document its
+	   existence in the Windows driver.  The effect of this
+	   command is that apps displaying the stream become sluggish
+	   with stuttering video. */
+	ret |= pvr2_encoder_vcmd(hdw, CX2341X_ENC_MISC,4, 4,1,0,0);
+#endif
+
+	ret |= pvr2_encoder_vcmd(hdw, CX2341X_ENC_MISC,4, 0,3,0,0);
+	ret |= pvr2_encoder_vcmd(hdw, CX2341X_ENC_MISC,4,15,0,0,0);
+
+	return ret;
+}
+
 int pvr2_encoder_configure(struct pvr2_hdw *hdw)
 {
 	int ret;
@@ -335,6 +402,8 @@ int pvr2_encoder_configure(struct pvr2_hdw *hdw)
 
 	ret = 0;
 
+	ret |= pvr2_encoder_prep_config(hdw);
+
 	if (!ret) ret = pvr2_encoder_vcmd(
 		hdw,CX2341X_ENC_SET_NUM_VSYNC_LINES, 2,
 		0xf0, 0xf0);