[media] bttv: Width must be a multiple of 16 when capturing planar formats

On my bttv card "Hauppauge WinTV [card=10]" capturing in YV12 fmt at max
size results in a solid green rectangle being captured (all colors 0 in
YUV).

This turns out to be caused by max-width (924) not being a multiple of 16.

We've likely never hit this problem before since normally xawtv / tvtime,
etc. will prefer packed pixel formats. But when using a video card which
is using xf86-video-modesetting + glamor, only planar XVideo fmts are
available, and xawtv will chose a matching capture format to avoid needing
to do conversion, triggering the solid green window problem.

Cc: stable@vger.kernel.org
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/pci/bt8xx/bttv-driver.c

@@ -2321,6 +2321,19 @@ static int bttv_g_fmt_vid_overlay(struct file *file, void *priv,
 	return 0;
 }
 
+static void bttv_get_width_mask_vid_cap(const struct bttv_format *fmt,
+					unsigned int *width_mask,
+					unsigned int *width_bias)
+{
+	if (fmt->flags & FORMAT_FLAGS_PLANAR) {
+		*width_mask = ~15; /* width must be a multiple of 16 pixels */
+		*width_bias = 8;   /* nearest */
+	} else {
+		*width_mask = ~3; /* width must be a multiple of 4 pixels */
+		*width_bias = 2;  /* nearest */
+	}
+}
+
 static int bttv_try_fmt_vid_cap(struct file *file, void *priv,
 						struct v4l2_format *f)
 {
@@ -2330,6 +2343,7 @@ static int bttv_try_fmt_vid_cap(struct file *file, void *priv,
 	enum v4l2_field field;
 	__s32 width, height;
 	__s32 height2;
+	unsigned int width_mask, width_bias;
 	int rc;
 
 	fmt = format_by_fourcc(f->fmt.pix.pixelformat);
@@ -2362,9 +2376,9 @@ static int bttv_try_fmt_vid_cap(struct file *file, void *priv,
 	width = f->fmt.pix.width;
 	height = f->fmt.pix.height;
 
+	bttv_get_width_mask_vid_cap(fmt, &width_mask, &width_bias);
 	rc = limit_scaled_size_lock(fh, &width, &height, field,
-			       /* width_mask: 4 pixels */ ~3,
-			       /* width_bias: nearest */ 2,
+			       width_mask, width_bias,
 			       /* adjust_size */ 1,
 			       /* adjust_crop */ 0);
 	if (0 != rc)
@@ -2397,6 +2411,7 @@ static int bttv_s_fmt_vid_cap(struct file *file, void *priv,
 	struct bttv_fh *fh = priv;
 	struct bttv *btv = fh->btv;
 	__s32 width, height;
+	unsigned int width_mask, width_bias;
 	enum v4l2_field field;
 
 	retval = bttv_switch_type(fh, f->type);
@@ -2411,9 +2426,10 @@ static int bttv_s_fmt_vid_cap(struct file *file, void *priv,
 	height = f->fmt.pix.height;
 	field = f->fmt.pix.field;
 
+	fmt = format_by_fourcc(f->fmt.pix.pixelformat);
+	bttv_get_width_mask_vid_cap(fmt, &width_mask, &width_bias);
 	retval = limit_scaled_size_lock(fh, &width, &height, f->fmt.pix.field,
-			       /* width_mask: 4 pixels */ ~3,
-			       /* width_bias: nearest */ 2,
+			       width_mask, width_bias,
 			       /* adjust_size */ 1,
 			       /* adjust_crop */ 1);
 	if (0 != retval)
@@ -2421,8 +2437,6 @@ static int bttv_s_fmt_vid_cap(struct file *file, void *priv,
 
 	f->fmt.pix.field = field;
 
-	fmt = format_by_fourcc(f->fmt.pix.pixelformat);
-
 	/* update our state informations */
 	fh->fmt              = fmt;
 	fh->cap.field        = f->fmt.pix.field;