path: root/v4l2-apps/libv4l2util/v4l2_driver.c

/*
   Copyright (C) 2006 Mauro Carvalho Chehab <mchehab@infradead.org>

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.
  */

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <malloc.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <stdlib.h>

#include "v4l2_driver.h"

/****************************************************************************
	Auxiliary routines
 ****************************************************************************/
static int xioctl (int fd, int request, void *arg)
{
	int r;

	do r = ioctl (fd, request, arg);
	while (-1 == r && EINTR == errno);

	return r;
}

static void free_list(struct drv_list **list_ptr)
{
	struct drv_list *prev,*cur;

	if (list_ptr==NULL)
		return;

	prev=*list_ptr;
	if (prev==NULL)
		return;

	do {
		cur=prev->next;
		if (prev->curr)
			free (prev->curr);	// Free data
		free (prev);			// Free list
		prev=cur;
	} while (prev);

	*list_ptr=NULL;
}

/****************************************************************************
	Auxiliary Arrays to aid debug messages
 ****************************************************************************/
char *v4l2_field_names[] = {
	[V4L2_FIELD_ANY]        = "any",
	[V4L2_FIELD_NONE]       = "none",
	[V4L2_FIELD_TOP]        = "top",
	[V4L2_FIELD_BOTTOM]     = "bottom",
	[V4L2_FIELD_INTERLACED] = "interlaced",
	[V4L2_FIELD_SEQ_TB]     = "seq-tb",
	[V4L2_FIELD_SEQ_BT]     = "seq-bt",
	[V4L2_FIELD_ALTERNATE]  = "alternate",
};

char *v4l2_type_names[] = {
	[V4L2_BUF_TYPE_VIDEO_CAPTURE]      = "video-cap",
	[V4L2_BUF_TYPE_VIDEO_OVERLAY]      = "video-over",
	[V4L2_BUF_TYPE_VIDEO_OUTPUT]       = "video-out",
	[V4L2_BUF_TYPE_VBI_CAPTURE]        = "vbi-cap",
	[V4L2_BUF_TYPE_VBI_OUTPUT]         = "vbi-out",
	[V4L2_BUF_TYPE_SLICED_VBI_CAPTURE] = "sliced-vbi-cap",
	[V4L2_BUF_TYPE_SLICED_VBI_OUTPUT]  = "slicec-vbi-out",
};

static char *v4l2_memory_names[] = {
	[V4L2_MEMORY_MMAP]    = "mmap",
	[V4L2_MEMORY_USERPTR] = "userptr",
	[V4L2_MEMORY_OVERLAY] = "overlay",
};

#define ARRAY_SIZE(arr) (sizeof(arr)/sizeof(*arr))
#define prt_names(a,arr) (((a)<ARRAY_SIZE(arr))?arr[a]:"unknown")

char *prt_caps(uint32_t caps)
{
	static char s[4096]="";

	if (V4L2_CAP_VIDEO_CAPTURE & caps)
		strcat (s,"CAPTURE ");
	if (V4L2_CAP_VIDEO_OUTPUT & caps)
		strcat (s,"OUTPUT ");
	if (V4L2_CAP_VIDEO_OVERLAY & caps)
		strcat (s,"OVERLAY ");
	if (V4L2_CAP_VBI_CAPTURE & caps)
		strcat (s,"VBI_CAPTURE ");
	if (V4L2_CAP_VBI_OUTPUT & caps)
		strcat (s,"VBI_OUTPUT ");
	if (V4L2_CAP_SLICED_VBI_CAPTURE & caps)
		strcat (s,"SLICED_VBI_CAPTURE ");
	if (V4L2_CAP_SLICED_VBI_OUTPUT & caps)
		strcat (s,"SLICED_VBI_OUTPUT ");
	if (V4L2_CAP_RDS_CAPTURE & caps)
		strcat (s,"RDS_CAPTURE ");
	if (V4L2_CAP_TUNER & caps)
		strcat (s,"TUNER ");
	if (V4L2_CAP_AUDIO & caps)
		strcat (s,"AUDIO ");
	if (V4L2_CAP_RADIO & caps)
		strcat (s,"RADIO ");
	if (V4L2_CAP_READWRITE & caps)
		strcat (s,"READWRITE ");
	if (V4L2_CAP_ASYNCIO & caps)
		strcat (s,"ASYNCIO ");
	if (V4L2_CAP_STREAMING & caps)
		strcat (s,"STREAMING ");

	return s;
}

static void prt_buf_info(char *name,struct v4l2_buffer *p)
{
	struct v4l2_timecode *tc=&p->timecode;

	printf ("%s: %02ld:%02d:%02d.%08ld index=%d, type=%s, "
		"bytesused=%d, flags=0x%08x, "
		"field=%s, sequence=%d, memory=%s, offset=0x%08x, length=%d\n",
		name, (p->timestamp.tv_sec/3600),
		(int)(p->timestamp.tv_sec/60)%60,
		(int)(p->timestamp.tv_sec%60),
		p->timestamp.tv_usec,
		p->index,
		prt_names(p->type,v4l2_type_names),
		p->bytesused,p->flags,
		prt_names(p->field,v4l2_field_names),
		p->sequence,
		prt_names(p->memory,v4l2_memory_names),
		p->m.offset,
		p->length);
	tc=&p->timecode;
	printf ("\tTIMECODE: %02d:%02d:%02d type=%d, "
		"flags=0x%08x, frames=%d, userbits=0x%08x\n",
		tc->hours,tc->minutes,tc->seconds,
		tc->type, tc->flags, tc->frames, *(uint32_t *) tc->userbits);
}

/****************************************************************************
	Open V4L2 devices
 ****************************************************************************/
int v4l2_open (char *device, int debug, struct v4l2_driver *drv)
{
	int ret;

	memset(drv,0,sizeof(*drv));

	drv->debug=debug;

	if ((drv->fd = open(device, O_RDWR )) < 0) {
		return(-errno);
	}

	ret=xioctl(drv->fd,VIDIOC_QUERYCAP,(void *) &drv->cap);
	if (!ret && drv->debug) {
		printf ("driver=%s, card=%s, bus=%s, version=%d.%d.%d, "
			"capabilities=%s\n",
			drv->cap.driver,drv->cap.card,drv->cap.bus_info,
			(drv->cap.version >> 16) & 0xff,
			(drv->cap.version >>  8) & 0xff,
			drv->cap.version         & 0xff,
			prt_caps(drv->cap.capabilities));


	}
	return ret;
}


/****************************************************************************
	V4L2 Eumberations
 ****************************************************************************/
int v4l2_enum_stds (struct v4l2_driver *drv)
{
	struct v4l2_standard	*p=NULL;
	struct drv_list		*list;
	int			ok=0,ret,i;
	v4l2_std_id		id;

	free_list(&drv->stds);

	list=drv->stds=calloc(1,sizeof(*drv->stds));
	assert (list!=NULL);

	for (i=0; ok==0; i++) {
		p=calloc(1,sizeof(*p));
		assert (p);

		p->index=i;
		ok=xioctl(drv->fd,VIDIOC_ENUMSTD,p);
		if (ok<0) {
			ok=-errno;
			free(p);
			break;
		}
		if (drv->debug) {
			printf ("STANDARD: index=%d, id=0x%08x, name=%s, fps=%.3f, "
				"framelines=%d\n", p->index,
				(unsigned int)p->id, p->name,
				1.*p->frameperiod.denominator/p->frameperiod.numerator,
				p->framelines);
		}
		if (list->curr) {
			list->next=calloc(1,sizeof(*list->next));
			list=list->next;
			assert (list!=NULL);
		}
		list->curr=p;
	}
	if (i>0 && ok==-EINVAL)
		return 0;

	return ok;
}

int v4l2_enum_input (struct v4l2_driver *drv)
{
	struct v4l2_input	*p=NULL;
	struct drv_list		*list;
	int			ok=0,ret,i;
	v4l2_std_id		id;

	free_list(&drv->inputs);

	list=drv->inputs=calloc(1,sizeof(*drv->inputs));
	assert (list!=NULL);

	for (i=0; ok==0; i++) {
		p=calloc(1,sizeof(*p));
		assert (p);
		p->index=i;
		ok=xioctl(drv->fd,VIDIOC_ENUMINPUT,p);
		if (ok<0) {
			ok=errno;
			free(p);
			break;
		}
		if (drv->debug) {
			printf ("INPUT: index=%d, name=%s, type=%d, audioset=%d, "
				"tuner=%d, std=%08x, status=%d\n",
				p->index,p->name,p->type,p->audioset, p->tuner,
				(unsigned int)p->std, p->status);
		}
		if (list->curr) {
			list->next=calloc(1,sizeof(*list->next));
			list=list->next;
			assert (list!=NULL);
		}
		list->curr=p;
	}
	if (i>0 && ok==-EINVAL)
		return 0;
	return ok;
}

int v4l2_enum_fmt (struct v4l2_driver *drv, enum v4l2_buf_type type)
{
	struct v4l2_fmtdesc 	*p=NULL;
	struct v4l2_format	fmt;
	struct drv_list		*list;
	int			ok=0,ret,i;
	v4l2_std_id		id;

	free_list(&drv->fmt_caps);

	list=drv->fmt_caps=calloc(1,sizeof(*drv->fmt_caps));
	assert (list!=NULL);

	for (i=0; ok==0; i++) {
		p=calloc(1,sizeof(*p));
		assert (p!=NULL);

		p->index=i;
		p->type =type;

		ok=xioctl(drv->fd,VIDIOC_ENUM_FMT,p);
		if (ok<0) {
			ok=errno;
			free(p);
			break;
		}
		if (drv->debug) {
			printf ("FORMAT: index=%d, type=%d, flags=%d, description='%s'\n\t"
				"fourcc=%c%c%c%c\n",
				p->index, p->type, p->flags,p->description,
				p->pixelformat & 0xff,
				(p->pixelformat >>  8) & 0xff,
				(p->pixelformat >> 16) & 0xff,
				(p->pixelformat >> 24) & 0xff
				);
		}
		if (list->curr) {
			list->next=calloc(1,sizeof(*list->next));
			list=list->next;
			assert (list!=NULL);
		}
		list->curr=p;
	}
	if (i>0 && ok==-EINVAL)
		return 0;
	return ok;
}

/****************************************************************************
	Set routines - currently, it also checks results with Get
 ****************************************************************************/
int v4l2_setget_std (struct v4l2_driver *drv, enum v4l2_direction dir, v4l2_std_id *id)
{
	v4l2_std_id		s_id=*id;
	int			ret=0;
	char			s[256];

	if (dir & V4L2_SET) {
		ret=xioctl(drv->fd,VIDIOC_S_STD,&s_id);
		if (ret<0) {
			ret=errno;

			sprintf (s,"while trying to set STD to %08x",
								(unsigned int) *id);
			perror(s);
		}
	}

	if (dir & V4L2_GET) {
		ret=xioctl(drv->fd,VIDIOC_G_STD,&s_id);
		if (ret<0) {
			ret=errno;
			perror ("while trying to get STD id");
		}
	}

	if (dir == V4L2_SET_GET) {
		if (*id & s_id) {
			if (*id != s_id) {
				printf ("Warning: Received a std subset (%08x"
					" std) while trying to adjust to %08x\n",
					(unsigned int) s_id,(unsigned int) *id);
			}
		} else {
			fprintf (stderr,"Error: Received %08x std while trying"
				" to adjust to %08x\n",
				(unsigned int) s_id,(unsigned int) *id);
		}
	}
	return ret;
}

int v4l2_setget_input (struct v4l2_driver *drv, enum v4l2_direction dir, struct v4l2_input *input)
{
	int			ok=0,ret,i;
	unsigned int		inp=input->index;
	char			s[256];

	if (dir & V4L2_SET) {
		ret=xioctl(drv->fd,VIDIOC_S_INPUT,input);
		if (ret<0) {
			ret=errno;
			sprintf (s,"while trying to set INPUT to %d\n", inp);
			perror(s);
		}
	}

	if (dir & V4L2_GET) {
		ret=xioctl(drv->fd,VIDIOC_G_INPUT,input);
		if (ret<0) {
			perror ("while trying to get INPUT id\n");
		}
	}

	if (dir & V4L2_SET_GET) {
		if (input->index != inp) {
			printf ("Input is different than expected (received %i, set %i)\n",
						inp, input->index);
		}
	}

	return ok;
}

int v4l2_gettryset_fmt_cap (struct v4l2_driver *drv, enum v4l2_direction dir,
		      struct v4l2_format *fmt,uint32_t width, uint32_t height,
		      uint32_t pixelformat, enum v4l2_field field)
{
	struct v4l2_pix_format  *pix=&(fmt->fmt.pix);
	int			ret=0;

	fmt->type=V4L2_BUF_TYPE_VIDEO_CAPTURE;
	if (dir == V4L2_GET) {
		ret=xioctl(drv->fd,VIDIOC_G_FMT,fmt);
		if (ret < 0) {
			ret=errno;
			perror("VIDIOC_G_FMT failed\n");
		}
		return ret;
	} else if (dir & (~(V4L2_TRY|V4L2_SET)) ) {
		perror ("Invalid direction\n");
		return EINVAL;
	}

	if (dir & (V4L2_TRY|V4L2_SET)) {
		pix->width       = width;
		pix->height      = height;
		pix->pixelformat = pixelformat;
		pix->field       = field;
	/*
		enum v4l2_colorspace	colorspace;
	*/

		if (dir & V4L2_TRY) {
			ret=xioctl(drv->fd,VIDIOC_TRY_FMT,fmt);
			if (ret < 0) {
				perror("VIDIOC_TRY_FMT failed\n");
			}
		}

		if (dir & V4L2_SET) {
			ret=xioctl(drv->fd,VIDIOC_S_FMT,fmt);
			if (ret < 0) {
				perror("VIDIOC_S_FMT failed\n");
			}
			drv->sizeimage=pix->sizeimage;
		}

		if (pix->pixelformat != pixelformat) {
			fprintf(stderr,"Error: asked for format %d, received %d",pixelformat,
				pix->pixelformat);
		}

		if (pix->width != width) {
			fprintf(stderr,"Error: asked for format %d, received %d\n",width,
				pix->width);
		}

		if (pix->height != height) {
			fprintf(stderr,"Error: asked for format %d, received %d\n",height,
				pix->height);
		}

		if (pix->bytesperline == 0 ) {
			fprintf(stderr,"Error: bytesperline = 0\n");
		}

		if (pix->sizeimage == 0 ) {
			fprintf(stderr,"Error: sizeimage = 0\n");
		}
	}

	if (drv->debug)
		printf( "FMT SET: %dx%d, fourcc=%c%c%c%c, %d bytes/line,"
			" %d bytes/frame, colorspace=0x%08x\n",
			pix->width,pix->height,
			pix->pixelformat & 0xff,
			(pix->pixelformat >>  8) & 0xff,
			(pix->pixelformat >> 16) & 0xff,
			(pix->pixelformat >> 24) & 0xff,
			pix->bytesperline,
			pix->sizeimage,
			pix->colorspace);

	return 0;
}

/****************************************************************************
	Get routines
 ****************************************************************************/
int v4l2_get_parm (struct v4l2_driver *drv)
{
	int ret;
	struct v4l2_captureparm *c;

	drv->parm.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	if ((ret=xioctl(drv->fd,VIDIOC_G_PARM,&drv->parm))>=0) {
		c=&drv->parm.parm.capture;
		printf ("PARM: capability=%d, capturemode=%d, %.3f fps "
			"ext=%x, readbuf=%d\n",
			c->capability,
			c->capturemode,
			c->timeperframe.denominator*1./c->timeperframe.numerator,
			c->extendedmode, c->readbuffers);
	} else {
		ret=errno;

		perror ("VIDIOC_G_PARM");
	}

	return ret;
}

/****************************************************************************
	Queue and stream control
 ****************************************************************************/

int v4l2_free_bufs(struct v4l2_driver *drv)
{
	unsigned int i;

	if (!drv->n_bufs)
		return 0;

	/* Requests the driver to free all buffers */
	drv->reqbuf.count  = 0;
	drv->reqbuf.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	drv->reqbuf.memory = V4L2_MEMORY_MMAP;

	/* stop capture */
	if (xioctl(drv->fd,VIDIOC_STREAMOFF,&drv->reqbuf.type)<0)
		return errno;

	sleep (1);	// FIXME: Should check if all buffers are stopped

/* V4L2 API says REQBUFS with count=0 should be used to release buffer.
   However, video-buf.c doesn't implement it.
 */
#if 0
	if (xioctl(drv->fd,VIDIOC_REQBUFS,&drv->reqbuf)<0) {
		perror("reqbufs while freeing buffers");
		return errno;
	}
#endif

	if (drv->reqbuf.count != 0) {
		fprintf(stderr,"REQBUFS returned %d buffers while asking for freeing it!\n",
			drv->reqbuf.count);
	}

	for (i = 0; i < drv->n_bufs; i++) {
		if (drv->bufs[i].length)
			munmap(drv->bufs[i].start, drv->bufs[i].length);
		if (drv->v4l2_bufs[i])
			free (drv->v4l2_bufs[i]);
	}

	free(drv->v4l2_bufs);
	free(drv->bufs);

	drv->v4l2_bufs=NULL;
	drv->bufs=NULL;
	drv->n_bufs=0;

	return 0;
}

int v4l2_mmap_bufs(struct v4l2_driver *drv, unsigned int num_buffers)
{
	/* Frees previous allocations, if required */
	v4l2_free_bufs(drv);

	if (drv->sizeimage==0) {
		fprintf(stderr,"Image size is zero! Can't proceed\n");
		return -1;
	}
	/* Requests the specified number of buffers */
	drv->reqbuf.count  = num_buffers;
	drv->reqbuf.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	drv->reqbuf.memory = V4L2_MEMORY_MMAP;

	if (xioctl(drv->fd,VIDIOC_REQBUFS,&drv->reqbuf)<0) {
		perror("reqbufs");
		return errno;
	}

	if (drv->debug)
		printf ("REQBUFS: count=%d, type=%s, memory=%s\n",
				drv->reqbuf.count,
				prt_names(drv->reqbuf.type,v4l2_type_names),
				prt_names(drv->reqbuf.memory,v4l2_memory_names));

	/* Allocates the required number of buffers */
	drv->v4l2_bufs=calloc(drv->reqbuf.count, sizeof(*drv->v4l2_bufs));
	assert(drv->v4l2_bufs!=NULL);
	drv->bufs=calloc(drv->reqbuf.count, sizeof(*drv->bufs));
	assert(drv->bufs!=NULL);

	for (drv->n_bufs = 0; drv->n_bufs < drv->reqbuf.count; drv->n_bufs++) {
		struct v4l2_buffer *p;
		struct v4l2_timecode *tc;

		/* Requests kernel buffers to be mmapped */
		p=drv->v4l2_bufs[drv->n_bufs]=calloc(1,sizeof(*p));
		assert (p!=NULL);
		p->index  = drv->n_bufs;
		p->type   = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		p->memory = V4L2_MEMORY_MMAP;
		if (xioctl(drv->fd,VIDIOC_QUERYBUF,p)<0) {
			int ret=errno;
			perror("querybuf");

			free (drv->v4l2_bufs[drv->n_bufs]);

			v4l2_free_bufs(drv);
			return ret;
		}

		if (drv->debug)
			prt_buf_info("QUERYBUF",p);

		if (drv->sizeimage != p->length) {
			if (drv->sizeimage < p->length) {
				fprintf (stderr, "QUERYBUF: ERROR: VIDIOC_S_FMT said buffer should have %d size, but received %d from QUERYBUF!\n",
					drv->sizeimage, p->length);
			} else {
				fprintf (stderr, "QUERYBUF: Expecting %d size, received %d buff length\n",
					drv->sizeimage, p->length);
			}
		}

		drv->bufs[drv->n_bufs].length = p->length;
		drv->bufs[drv->n_bufs].start = 	mmap (NULL,	/* start anywhere */
			      p->length,
			      PROT_READ | PROT_WRITE,		/* required */
			      MAP_SHARED,			/* recommended */
			      drv->fd, p->m.offset);


		if (MAP_FAILED == drv->bufs[drv->n_bufs].start) {
			perror("mmap");

			free (drv->v4l2_bufs[drv->n_bufs]);
			v4l2_free_bufs(drv);
			return errno;
		}
	}

	return 0;
}

int v4l2_rcvbuf(struct v4l2_driver *drv, v4l2_recebe_buffer *rec_buf)
{
	int ret;

	struct v4l2_buffer buf;
	memset (&buf, 0, sizeof(buf));

	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	buf.memory = V4L2_MEMORY_MMAP;

	if (-1 == xioctl (drv->fd, VIDIOC_DQBUF, &buf)) {
		switch (errno) {
		case EAGAIN:
			return 0;

		case EIO:
			/* Could ignore EIO, see spec. */

			/* fall through */

		default:
			perror ("dqbuf");
			return errno;
		}
	}
	prt_buf_info("DQBUF",&buf);

	assert (buf.index < drv->n_bufs);

	ret = rec_buf (&buf,&drv->bufs[buf.index]);

	if (ret) {
		v4l2_free_bufs(drv);
		return ret;
	}

	if (-1 == xioctl (drv->fd, VIDIOC_QBUF, &buf)) {
		perror ("qbuf");
		return errno;
	}
	return 0;
}


int v4l2_start_streaming(struct v4l2_driver *drv)
{
	uint32_t	i;
	struct v4l2_buffer buf;

	if (drv->debug)
		printf("Activating %d queues\n", drv->n_bufs);
	for (i = 0; i < drv->n_bufs; i++) {
		int res;

		memset(&buf, 0, sizeof(buf));
		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		buf.memory = V4L2_MEMORY_MMAP;
		buf.index  = i;

		res = xioctl (drv->fd, VIDIOC_QBUF, &buf);

		if (!res)
			prt_buf_info("QBUF",&buf);
		else {
			perror("qbuf");
			return errno;
		}
	}

	/* Activates stream */
	if (drv->debug)
		printf("Enabling streaming\n");

	if (xioctl(drv->fd,VIDIOC_STREAMON,&drv->reqbuf.type)<0)
		return errno;

	return 0;
}

int v4l2_stop_streaming(struct v4l2_driver *drv)
{
	v4l2_free_bufs(drv);

	return 0;
}

/****************************************************************************
	Close V4L2, disallocating all structs
 ****************************************************************************/
int v4l2_close (struct v4l2_driver *drv)
{
	v4l2_free_bufs(drv);

	free_list(&drv->stds);
	free_list(&drv->inputs);
	free_list(&drv->fmt_caps);

	return (close(drv->fd));
}

/****************************************************************************
	Get/Set frequency
 ****************************************************************************/

int v4l2_getset_freq (struct v4l2_driver *drv, enum v4l2_direction dir,
		      double *freq)
{
	struct v4l2_tuner     tun;
	struct v4l2_frequency frq;
	double d = 62500;
	unsigned int counter;

	memset(&tun, 0, sizeof(tun));

	if (-1 == xioctl (drv->fd, VIDIOC_G_TUNER, &tun)) {
		perror ("g_tuner");
		printf("Assuming 62.5 kHz step\n");
	} else {
		if (tun.capability & V4L2_TUNER_CAP_LOW)
			d=62.5;
	}

	if (drv->debug) {
		if (tun.capability & V4L2_TUNER_CAP_LOW)
			printf("62.5 Hz step\n");
		else
			printf("62.5 kHz step\n");
	}

	memset(&frq, 0, sizeof(frq));

	frq.type = V4L2_TUNER_ANALOG_TV;

	if (dir & V4L2_GET) {
		if (-1 == xioctl (drv->fd, VIDIOC_G_FREQUENCY, &frq)) {
			perror ("s_frequency");
			return errno;
		}
		*freq = frq.frequency * d;
		if (drv->debug)
			printf("board is at freq %4.3f MHz (%d)\n",
				*freq/1000000, frq.frequency);
	} else {
		frq.frequency = (uint32_t)(((*freq)+d/2) / d);

		if (-1 == xioctl (drv->fd, VIDIOC_S_FREQUENCY, &frq)) {
			perror ("s_frequency");
			return errno;
		}
		if (drv->debug)
			printf("board set to freq %4.3f MHz (%d)\n",
				*freq/1000000, frq.frequency);

	}
	return 0;
}