V4L/DVB: v4l: add V4L2_PIX_FMT_Y4 and V4L2_PIX_FMT_Y6 pixelformats

Old 4 and 6 bit greyscale pixel formats for the old bw-qcam webcam.
This is needed to convert it to V4L2.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/v4l/pixfmt.xml

@@ -792,6 +792,18 @@ http://www.thedirks.org/winnov/</ulink></para></entry>
 	    <entry>'YYUV'</entry>
 	    <entry>unknown</entry>
 	  </row>
+	  <row id="V4L2-PIX-FMT-Y4">
+	    <entry><constant>V4L2_PIX_FMT_Y4</constant></entry>
+	    <entry>'Y04 '</entry>
+	    <entry>Old 4-bit greyscale format. Only the least significant 4 bits of each byte are used,
+the other bits are set to 0.</entry>
+	  </row>
+	  <row id="V4L2-PIX-FMT-Y6">
+	    <entry><constant>V4L2_PIX_FMT_Y6</constant></entry>
+	    <entry>'Y06 '</entry>
+	    <entry>Old 6-bit greyscale format. Only the least significant 6 bits of each byte are used,
+the other bits are set to 0.</entry>
+	  </row>
 	</tbody>
       </tgroup>
     </table>

include/linux/videodev2.h

@@ -294,6 +294,8 @@ struct v4l2_pix_format {
 
 /* Grey formats */
 #define V4L2_PIX_FMT_GREY    v4l2_fourcc('G', 'R', 'E', 'Y') /*  8  Greyscale     */
+#define V4L2_PIX_FMT_Y4      v4l2_fourcc('Y', '0', '4', ' ') /*  4  Greyscale     */
+#define V4L2_PIX_FMT_Y6      v4l2_fourcc('Y', '0', '6', ' ') /*  6  Greyscale     */
 #define V4L2_PIX_FMT_Y10     v4l2_fourcc('Y', '1', '0', ' ') /* 10  Greyscale     */
 #define V4L2_PIX_FMT_Y16     v4l2_fourcc('Y', '1', '6', ' ') /* 16  Greyscale     */