V4L/DVB (6345): ivtvfb: YUV handling of an image which is not visible in the display area

When the ivtvfb module is loaded, the YUV output is relative to the
framebuffer output. When a virtual screen size is used, the output area for
the YUV may actually be off screen. To prevent the hardware from crashing,
the current driver will ignore an off-screen position and leave the output
visible at the last on-screen position. This may not be desirable, so this
patch will switch off the YUV output should the image move off-screen, and
re-enable it should the image move on-screen again.

Signed-off-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/ivtv/ivtv-yuv.c

@@ -710,7 +710,7 @@ static u32 ivtv_yuv_window_setup (struct ivtv *itv, struct yuv_frame_info *windo
 
 	/* If there's nothing to safe to display, we may as well stop now */
 	if ((int)window->dst_w <= 2 || (int)window->dst_h <= 2 || (int)window->src_w <= 2 || (int)window->src_h <= 2) {
-		return 0;
+		return IVTV_YUV_UPDATE_INVALID;
 	}
 
 	/* Ensure video remains inside OSD area */
@@ -791,7 +791,7 @@ static u32 ivtv_yuv_window_setup (struct ivtv *itv, struct yuv_frame_info *windo
 
 	/* Check again. If there's nothing to safe to display, stop now */
 	if ((int)window->dst_w <= 2 || (int)window->dst_h <= 2 || (int)window->src_w <= 2 || (int)window->src_h <= 2) {
-		return 0;
+		return IVTV_YUV_UPDATE_INVALID;
 	}
 
 	/* Both x offset & width are linked, so they have to be done together */
@@ -840,12 +840,17 @@ void ivtv_yuv_work_handler (struct ivtv *itv)
 	if (!(yuv_update = ivtv_yuv_window_setup (itv, &window)))
 		return;
 
-	/* Update horizontal settings */
-	if (yuv_update & IVTV_YUV_UPDATE_HORIZONTAL)
-		ivtv_yuv_handle_horizontal(itv, &window);
+	if (yuv_update & IVTV_YUV_UPDATE_INVALID) {
+		write_reg(0x01008080, 0x2898);
+	} else if (yuv_update) {
+		write_reg(0x00108080, 0x2898);
 
-	if (yuv_update & IVTV_YUV_UPDATE_VERTICAL)
-		ivtv_yuv_handle_vertical(itv, &window);
+		if (yuv_update & IVTV_YUV_UPDATE_HORIZONTAL)
+			ivtv_yuv_handle_horizontal(itv, &window);
+
+		if (yuv_update & IVTV_YUV_UPDATE_VERTICAL)
+			ivtv_yuv_handle_vertical(itv, &window);
+	}
 
 	memcpy(&itv->yuv_info.old_frame_info, &window, sizeof (itv->yuv_info.old_frame_info));
 }
@@ -936,9 +941,6 @@ static void ivtv_yuv_init (struct ivtv *itv)
 		IVTV_DEBUG_WARN ("Failed to allocate yuv blanking buffer\n");
 	}
 
-	IVTV_DEBUG_WARN("Enable video output\n");
-	write_reg_sync(0x00108080, 0x2898);
-
 	/* Enable YUV decoder output */
 	write_reg_sync(0x01, IVTV_REG_VDM);
 

drivers/media/video/ivtv/ivtv-yuv.h

@@ -34,6 +34,7 @@
 
 #define IVTV_YUV_UPDATE_HORIZONTAL  0x01
 #define IVTV_YUV_UPDATE_VERTICAL    0x02
+#define IVTV_YUV_UPDATE_INVALID     0x04
 
 extern const u32 yuv_offset[4];