V4L/DVB (12239): em28xx: fix webcam scaling

While trying to fix an mt9v001 webcam, I noticed that HSCALE/VSCALE do
work with em28xx + webcam. The issue is that the scaling setup depends
on the number of visible rows/cols of the input image.

With mt9v011 (Silvercrest), the resolution is 640x480. So, the scaling
is different from a normal TV image (720x480 on NTSC). This were causing
a wrong scaling and a previous patch disabled scaling.

As each sensor have their different resolution setting, the xres/yres
should be adjusted accordingly with the input sensor.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-cards.c

@@ -58,8 +58,6 @@ static unsigned int card[]     = {[0 ... (EM28XX_MAXBOARDS - 1)] = UNSET };
 module_param_array(card,  int, NULL, 0444);
 MODULE_PARM_DESC(card,     "card type");
 
-#define MT9V011_VERSION                 0x8243
-
 /* Bitmask marking allocated devices from 0 to EM28XX_MAXBOARDS */
 static unsigned long em28xx_devused;
 
@@ -1730,10 +1728,12 @@ static int em28xx_hint_sensor(struct em28xx *dev)
 	version = be16_to_cpu(version_be);
 
 	switch (version) {
-	case MT9V011_VERSION:
+	case 0x8243:		/* mt9v011 640x480 1.3 Mpix sensor */
 		dev->model = EM2820_BOARD_SILVERCREST_WEBCAM;
 		sensor_name = "mt9v011";
 		dev->em28xx_sensor = EM28XX_MT9V011;
+		dev->sensor_xres = 640;
+		dev->sensor_yres = 480;
 		break;
 	default:
 		printk("Unknown Micron Sensor 0x%04x\n", be16_to_cpu(version));

drivers/media/video/em28xx/em28xx-core.c

@@ -707,10 +707,7 @@ static int em28xx_scaler_set(struct em28xx *dev, u16 h, u16 v)
 	u8 mode;
 	/* the em2800 scaler only supports scaling down to 50% */
 
-	if (dev->board.is_webcam) {
-		/* FIXME: Don't use the scaler yet */
-		mode = 0;
-	} else if (dev->board.is_em2800) {
+	if (dev->board.is_em2800) {
 		mode = (v ? 0x20 : 0x00) | (h ? 0x10 : 0x00);
 	} else {
 		u8 buf[2];

drivers/media/video/em28xx/em28xx-video.c

@@ -726,11 +726,7 @@ static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
 		return -EINVAL;
 	}
 
-	if (dev->board.is_webcam) {
-		/* FIXME: This is the only supported fmt */
-		width  = 640;
-		height = 480;
-	} else if (dev->board.is_em2800) {
+	if (dev->board.is_em2800) {
 		/* the em2800 can only scale down to 50% */
 		height = height > (3 * maxh / 4) ? maxh : maxh / 2;
 		width = width > (3 * maxw / 4) ? maxw : maxw / 2;
@@ -767,12 +763,6 @@ static int em28xx_set_video_format(struct em28xx *dev, unsigned int fourcc,
 {
 	struct em28xx_fmt     *fmt;
 
-	/* FIXME: This is the only supported fmt */
-	if (dev->board.is_webcam) {
-		width  = 640;
-		height = 480;
-	}
-
 	fmt = format_by_fourcc(fourcc);
 	if (!fmt)
 		return -EINVAL;

drivers/media/video/em28xx/em28xx.h

@@ -479,6 +479,7 @@ struct em28xx {
 	struct em28xx_board board;
 
 	enum em28xx_sensor em28xx_sensor;
+	int sensor_xres, sensor_yres;
 
 	unsigned int stream_on:1;	/* Locks streams */
 	unsigned int has_audio_class:1;
@@ -760,17 +761,23 @@ static inline int em28xx_gamma_set(struct em28xx *dev, s32 val)
 /*FIXME: maxw should be dependent of alt mode */
 static inline unsigned int norm_maxw(struct em28xx *dev)
 {
+	if (dev->board.is_webcam)
+		return dev->sensor_xres;
+
 	if (dev->board.max_range_640_480)
 		return 640;
-	else
+
 	return 720;
 }
 
 static inline unsigned int norm_maxh(struct em28xx *dev)
 {
+	if (dev->board.is_webcam)
+		return dev->sensor_yres;
+
 	if (dev->board.max_range_640_480)
 		return 480;
-	else
+
 	return (dev->norm & V4L2_STD_625_50) ? 576 : 480;
 }
 #endif