V4L/DVB (9133): v4l: disconnect kernel number from minor

The v4l core creates four different video devices (video, vbi, radio, vtx)
and each has its own range of minor numbers. However, modern devices keep
increasing the number of devices that they need so a maximum of 64 video
devices will not be enough in the future. In addition this scheme makes
it very hard to add new device types.

This patch disconnects the kernel number allocation (e.g. video0, video1,
etc.) from the actual minor number (just pick the first free minor).

This allows for much more flexibility in the future. However, it does
require the use of udev. For those who cannot use udev a new CONFIG option
was created that changes the allocation scheme back to the old behavior.

Thanks to Greg KH for suggesting this approach during the 2008 LPC.

In addition, several bugs were fixed in the ivtv and cx18 drivers: these
drivers try to allocate specific kernel numbers but that scheme contained
a bug which caused what should have been e.g. video17 to appear as e.g.
video2.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 25 insertions, 21 deletions

diff --git a/drivers/media/video/ivtv/ivtv-driver.c b/drivers/media/video/ivtv/ivtv-driver.c
index 6b04930d1278..7aa61b617496 100644
--- a/drivers/media/video/ivtv/ivtv-driver.c
+++ b/drivers/media/video/ivtv/ivtv-driver.c
@@ -61,14 +61,14 @@
 #include "tuner-xc2028.h"
 
 /* var to keep track of the number of array elements in use */
-int ivtv_cards_active = 0;
+int ivtv_cards_active;
 
 /* If you have already X v4l cards, then set this to X. This way
    the device numbers stay matched. Example: you have a WinTV card
    without radio and a PVR-350 with. Normally this would give a
    video1 device together with a radio0 device for the PVR. By
    setting this to 1 you ensure that radio0 is now also radio1. */
-int ivtv_first_minor = 0;
+int ivtv_first_minor;
 
 /* Master variable for all ivtv info */
 struct ivtv *ivtv_cards[IVTV_MAX_CARDS];
@@ -251,7 +251,7 @@ MODULE_PARM_DESC(newi2c,
 		 "\t\t\t-1 is autodetect, 0 is off, 1 is on\n"
 		 "\t\t\tDefault is autodetect");
 
-MODULE_PARM_DESC(ivtv_first_minor, "Set minor assigned to first card");
+MODULE_PARM_DESC(ivtv_first_minor, "Set kernel number assigned to first card");
 
 MODULE_AUTHOR("Kevin Thayer, Chris Kennedy, Hans Verkuil");
 MODULE_DESCRIPTION("CX23415/CX23416 driver");
diff --git a/drivers/media/video/ivtv/ivtv-streams.c b/drivers/media/video/ivtv/ivtv-streams.c
index 730e85d86fc8..24273fbea470 100644
--- a/drivers/media/video/ivtv/ivtv-streams.c
+++ b/drivers/media/video/ivtv/ivtv-streams.c
@@ -75,7 +75,7 @@ static const struct file_operations ivtv_v4l2_dec_fops = {
 static struct {
 	const char *name;
 	int vfl_type;
-	int minor_offset;
+	int num_offset;
 	int dma, pio;
 	enum v4l2_buf_type buf_type;
 	const struct file_operations *fops;
@@ -171,8 +171,8 @@ static void ivtv_stream_init(struct ivtv *itv, int type)
 static int ivtv_prep_dev(struct ivtv *itv, int type)
 {
 	struct ivtv_stream *s = &itv->streams[type];
-	int minor_offset = ivtv_stream_info[type].minor_offset;
-	int minor;
+	int num_offset = ivtv_stream_info[type].num_offset;
+	int num = itv->num + ivtv_first_minor + num_offset;
 
 	/* These four fields are always initialized. If v4l2dev == NULL, then
 	   this stream is not in use. In that case no other fields but these
@@ -188,9 +188,6 @@ static int ivtv_prep_dev(struct ivtv *itv, int type)
 	if (type >= IVTV_DEC_STREAM_TYPE_MPG && !(itv->v4l2_cap & V4L2_CAP_VIDEO_OUTPUT))
 		return 0;
 
-	/* card number + user defined offset + device offset */
-	minor = itv->num + ivtv_first_minor + minor_offset;
-
 	/* User explicitly selected 0 buffers for these streams, so don't
 	   create them. */
 	if (ivtv_stream_info[type].dma != PCI_DMA_NONE &&
@@ -211,7 +208,7 @@ static int ivtv_prep_dev(struct ivtv *itv, int type)
 	snprintf(s->v4l2dev->name, sizeof(s->v4l2dev->name), "ivtv%d %s",
 			itv->num, s->name);
 
-	s->v4l2dev->minor = minor;
+	s->v4l2dev->num = num;
 	s->v4l2dev->parent = &itv->dev->dev;
 	s->v4l2dev->fops = ivtv_stream_info[type].fops;
 	s->v4l2dev->release = video_device_release;
@@ -250,39 +247,46 @@ static int ivtv_reg_dev(struct ivtv *itv, int type)
 {
 	struct ivtv_stream *s = &itv->streams[type];
 	int vfl_type = ivtv_stream_info[type].vfl_type;
-	int minor;
+	int num;
 
 	if (s->v4l2dev == NULL)
 		return 0;
 
-	minor = s->v4l2dev->minor;
+	num = s->v4l2dev->num;
+	/* card number + user defined offset + device offset */
+	if (type != IVTV_ENC_STREAM_TYPE_MPG) {
+		struct ivtv_stream *s_mpg = &itv->streams[IVTV_ENC_STREAM_TYPE_MPG];
+
+		if (s_mpg->v4l2dev)
+			num = s_mpg->v4l2dev->num + ivtv_stream_info[type].num_offset;
+	}
+
 	/* Register device. First try the desired minor, then any free one. */
-	if (video_register_device(s->v4l2dev, vfl_type, minor) &&
-			video_register_device(s->v4l2dev, vfl_type, -1)) {
-		IVTV_ERR("Couldn't register v4l2 device for %s minor %d\n",
-				s->name, minor);
+	if (video_register_device(s->v4l2dev, vfl_type, num)) {
+		IVTV_ERR("Couldn't register v4l2 device for %s kernel number %d\n",
+				s->name, num);
 		video_device_release(s->v4l2dev);
 		s->v4l2dev = NULL;
 		return -ENOMEM;
 	}
+	num = s->v4l2dev->num;
 
 	switch (vfl_type) {
 	case VFL_TYPE_GRABBER:
 		IVTV_INFO("Registered device video%d for %s (%d kB)\n",
-			s->v4l2dev->minor, s->name, itv->options.kilobytes[type]);
+			num, s->name, itv->options.kilobytes[type]);
 		break;
 	case VFL_TYPE_RADIO:
 		IVTV_INFO("Registered device radio%d for %s\n",
-			s->v4l2dev->minor - MINOR_VFL_TYPE_RADIO_MIN, s->name);
+			num, s->name);
 		break;
 	case VFL_TYPE_VBI:
 		if (itv->options.kilobytes[type])
 			IVTV_INFO("Registered device vbi%d for %s (%d kB)\n",
-				s->v4l2dev->minor - MINOR_VFL_TYPE_VBI_MIN,
-				s->name, itv->options.kilobytes[type]);
+				num, s->name, itv->options.kilobytes[type]);
 		else
 			IVTV_INFO("Registered device vbi%d for %s\n",
-				s->v4l2dev->minor - MINOR_VFL_TYPE_VBI_MIN, s->name);
+				num, s->name);
 		break;
 	}
 	return 0;