Re: Regarding request for IBM camera patch to be applied to the main tree

[David Hilvert <dhilvert@gmail.com>]

On Fri, 21 Dec 2007 14:32:09 -0800
Greg KH <greg@kroah.com> wrote:

> On Fri, Dec 21, 2007 at 03:21:30PM -0600, David Hilvert wrote:
> > > > http://www.linux-usb.org/ibmcam/
> > 
> > > > http://auricle.dyndns.org/xvp610/
> > 
> > [Remainder of private e-mail context snipped; message has been blind-CC'ed to
> > the original recipients.  Please CC any replies intended for me.]
> > 
> > As the author of the second patch noted, I had avoided sending it to lkml due
> > to the difficulty of determining whether the patch is correct (e.g., having no
> > ill effect on other cameras), due, in turn, to lack of documentation for this
> > series of cameras.  Perhaps dmitri could comment further on this, if he has
> > time and access to test on any other cameras that might fall under the 'model
> > 3' designation (whatever this designation might mean).  The (rather old, now)
> > patch in question (against 2.6.1 or so, and perhaps other versions) follows; if
> > I recall correctly, it was designed to minimize change lines rather than
> > provide for overall clarity, so that a clearer final implementation is probably
> > possible.
> > 
> > 
> > diff -urN linux-2.6.1/drivers/usb/media/ibmcam.c linux-2.6.1-patched/drivers/usb/media/ibmcam.c
> > --- linux-2.6.1/drivers/usb/media/ibmcam.c	Fri Jan  9 00:59:19 2004
> > +++ linux-2.6.1-patched/drivers/usb/media/ibmcam.c	Fri Feb  6 14:54:33 2004
> 
> I suggest forward porting it to the latest tree and submit it to the usb
> video maintainers for inclusion.
> 
> thanks,
> 
> greg k-h

Port to 2.6.23.12 follows:


--- linux-2.6.23.12/drivers/media/video/usbvideo/ibmcam.c	2007-12-18 21:55:57.000000000 +0000
+++ linux-2.6.23.12-patched/drivers/media/video/usbvideo/ibmcam.c	2007-12-26 20:34:45.000000000 +0000
@@ -802,6 +802,21 @@
 		return scan_Continue;
 }
 
+/*
+ * ibmcam_model3_parse_lines()
+ *
+ * | Even lines |     Odd Lines       |
+ * -----------------------------------|
+ * |YYY........Y|UYVYUYVY.........UYVY|
+ * |YYY........Y|UYVYUYVY.........UYVY| 
+ * |............|.....................|
+ * |YYY........Y|UYVYUYVY.........UYVY| 
+ * |------------+---------------------|
+ *
+ * There is one (U, V) chroma pair for every four luma (Y) values.  This
+ * function reads a pair of lines at a time and obtains missing chroma values
+ * from adjacent pixels.
+ */
 static enum ParseState ibmcam_model3_parse_lines(
 	struct uvd *uvd,
 	struct usbvideo_frame *frame,
@@ -816,6 +831,7 @@
 	const int ccm = 128; /* Color correction median - see below */
 	int i, u, v, rw, data_w=0, data_h=0, color_corr;
 	static unsigned char lineBuffer[640*3];
+	int line;
 
 	color_corr = (uvd->vpic.colour - 0x8000) >> 8; /* -128..+127 = -ccm..+(ccm-1)*/
 	RESTRICT_TO_RANGE(color_corr, -ccm, ccm+1);
@@ -869,15 +885,15 @@
 		return scan_NextFrame;
 	}
 
-	/* Make sure there's enough data for the entire line */
-	len = 3 * data_w; /* <y-data> <uv-data> */
+	/* Make sure that lineBuffer can store two lines of data */
+	len = 3 * data_w; /* <y-data> <uyvy-data> */
 	assert(len <= sizeof(lineBuffer));
 
-	/* Make sure there's enough data for the entire line */
+	/* Make sure there's enough data for two lines */
 	if (RingQueue_GetLength(&uvd->dp) < len)
 		return scan_Out;
 
-	/* Suck one line out of the ring queue */
+	/* Suck two lines of data out of the ring queue */
 	RingQueue_Dequeue(&uvd->dp, lineBuffer, len);
 
 	data = lineBuffer;
@@ -887,15 +903,23 @@
 	rw = (int)VIDEOSIZE_Y(frame->request) - (int)(frame->curline) - 1;
 	RESTRICT_TO_RANGE(rw, 0, VIDEOSIZE_Y(frame->request)-1);
 
-	for (i = 0; i < VIDEOSIZE_X(frame->request); i++) {
-		int y, rv, gv, bv;	/* RGB components */
+	/* Iterate over two lines. */
+	for (line = 0; line < 2; line++) {
+		for (i = 0; i < VIDEOSIZE_X(frame->request); i++) {
+			int y;
+			int rv, gv, bv;	/* RGB components */
+
+			if (i >= data_w) {
+				RGB24_PUTPIXEL(frame, i, rw, 0, 0, 0);
+				continue;
+			}
 
-		if (i < data_w) {
-			y = data[i];	/* Luminosity is the first line */
+			/* first line is YYY...Y; second is UYVY...UYVY */
+			y = data[(line == 0) ? i : (i*2 + 1)];
 
 			/* Apply static color correction */
-			u = color[i*2] + hue_corr;
-			v = color[i*2 + 1] + hue2_corr;
+			u = color[(i/2)*4] + hue_corr;
+			v = color[(i/2)*4 + 2] + hue2_corr;
 
 			/* Apply color correction */
 			if (color_corr != 0) {
@@ -903,13 +927,21 @@
 				u = 128 + ((ccm + color_corr) * (u - 128)) / ccm;
 				v = 128 + ((ccm + color_corr) * (v - 128)) / ccm;
 			}
-		} else
-			y = 0, u = v = 128;
 
-		YUV_TO_RGB_BY_THE_BOOK(y, u, v, rv, gv, bv);
-		RGB24_PUTPIXEL(frame, i, rw, rv, gv, bv); /* Done by deinterlacing now */
+
+			YUV_TO_RGB_BY_THE_BOOK(y, u, v, rv, gv, bv);
+			RGB24_PUTPIXEL(frame, i, rw, rv, gv, bv);  /* No deinterlacing */
+		}
+
+		/* Check for the end of requested data */
+		if (rw == 0)
+			break;
+
+		/* Prepare for the second line */
+		rw--;
+		data = lineBuffer + data_w;
 	}
-	frame->deinterlace = Deinterlace_FillEvenLines;
+	frame->deinterlace = Deinterlace_None;
 
 	/*
 	 * Account for number of bytes that we wrote into output V4L frame.
--
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