media: gspca: fix g/s_parm handling

Fix v4l2-compliance error: s_parm never set V4L2_CAP_TIMEPERFRAME.
Also various g/s_parm-related cleanups.

Signed-off-by: Hans Verkuil <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/usb/gspca/gspca.c

···
 {
 	struct gspca_dev *gspca_dev = video_drvdata(filp);
 
-	parm->parm.capture.readbuffers = 2;
+	parm->parm.capture.readbuffers = gspca_dev->queue.min_buffers_needed;
 
-	if (gspca_dev->sd_desc->get_streamparm) {
-		gspca_dev->usb_err = 0;
-		gspca_dev->sd_desc->get_streamparm(gspca_dev, parm);
-		return gspca_dev->usb_err;
-	}
-	return 0;
+	if (!gspca_dev->sd_desc->get_streamparm)
+		return 0;
+
+	parm->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
+	gspca_dev->usb_err = 0;
+	gspca_dev->sd_desc->get_streamparm(gspca_dev, parm);
+	return gspca_dev->usb_err;
 }
 
 static int vidioc_s_parm(struct file *filp, void *priv,
···
 {
 	struct gspca_dev *gspca_dev = video_drvdata(filp);
 
-	parm->parm.capture.readbuffers = 2;
+	parm->parm.capture.readbuffers = gspca_dev->queue.min_buffers_needed;
 
-	if (gspca_dev->sd_desc->set_streamparm) {
-		gspca_dev->usb_err = 0;
-		gspca_dev->sd_desc->set_streamparm(gspca_dev, parm);
-		return gspca_dev->usb_err;
+	if (!gspca_dev->sd_desc->set_streamparm) {
+		parm->parm.capture.capability = 0;
+		return 0;
 	}
 
-	return 0;
+	parm->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
+	gspca_dev->usb_err = 0;
+	gspca_dev->sd_desc->set_streamparm(gspca_dev, parm);
+	return gspca_dev->usb_err;
 }
 
 static int gspca_queue_setup(struct vb2_queue *vq,

drivers/media/usb/gspca/ov534.c

···
 	struct v4l2_fract *tpf = &cp->timeperframe;
 	struct sd *sd = (struct sd *) gspca_dev;
 
-	cp->capability |= V4L2_CAP_TIMEPERFRAME;
 	tpf->numerator = 1;
 	tpf->denominator = sd->frame_rate;
 }

drivers/media/usb/gspca/topro.c

···
 	struct v4l2_fract *tpf = &cp->timeperframe;
 	int fr, i;
 
-	cp->capability |= V4L2_CAP_TIMEPERFRAME;
 	tpf->numerator = 1;
 	i = get_fr_idx(gspca_dev);
 	if (i & 0x80) {