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V4L/DVB (5765): SN9C1xx driver updates
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- Add support for pair OV7630+SN9C120
- Better and safe locking mechanism of the device structure on open(),
  close() and disconnect()
- Use kref for handling device deallocation
- Generic cleanups

Signed-off-by: Luca Risolia <luca.risolia@studio.unibo.it>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
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Luca Risolia authored and Mauro Carvalho Chehab committed Jul 18, 2007
1 parent a6e2b40 commit 3770be3
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Showing 5 changed files with 358 additions and 129 deletions.
3 changes: 2 additions & 1 deletion Documentation/video4linux/sn9c102.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -436,7 +436,7 @@ HV7131D Hynix Semiconductor | Yes No No No
HV7131R Hynix Semiconductor | No Yes Yes Yes
MI-0343 Micron Technology | Yes No No No
MI-0360 Micron Technology | No Yes Yes Yes
OV7630 OmniVision Technologies | Yes Yes No No
OV7630 OmniVision Technologies | Yes Yes Yes Yes
OV7660 OmniVision Technologies | No No Yes Yes
PAS106B PixArt Imaging | Yes No No No
PAS202B PixArt Imaging | Yes Yes No No
Expand Down Expand Up @@ -583,6 +583,7 @@ order):
- Bertrik Sikken, who reverse-engineered and documented the Huffman compression
algorithm used in the SN9C101, SN9C102 and SN9C103 controllers and
implemented the first decoder;
- Ronny Standke for the donation of a webcam;
- Mizuno Takafumi for the donation of a webcam;
- an "anonymous" donator (who didn't want his name to be revealed) for the
donation of a webcam.
Expand Down
9 changes: 6 additions & 3 deletions drivers/media/video/sn9c102/sn9c102.h
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/stddef.h>
#include <linux/kref.h>

#include "sn9c102_config.h"
#include "sn9c102_sensor.h"
Expand Down Expand Up @@ -94,7 +95,7 @@ struct sn9c102_module_param {
};

static DEFINE_MUTEX(sn9c102_sysfs_lock);
static DECLARE_RWSEM(sn9c102_disconnect);
static DECLARE_RWSEM(sn9c102_dev_lock);

struct sn9c102_device {
struct video_device* v4ldev;
Expand Down Expand Up @@ -122,12 +123,14 @@ struct sn9c102_device {

struct sn9c102_module_param module_param;

struct kref kref;
enum sn9c102_dev_state state;
u8 users;

struct mutex dev_mutex, fileop_mutex;
struct completion probe;
struct mutex open_mutex, fileop_mutex;
spinlock_t queue_lock;
wait_queue_head_t open, wait_frame, wait_stream;
wait_queue_head_t wait_open, wait_frame, wait_stream;
};

/*****************************************************************************/
Expand Down
173 changes: 103 additions & 70 deletions drivers/media/video/sn9c102/sn9c102_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,8 +48,8 @@
#define SN9C102_MODULE_AUTHOR "(C) 2004-2007 Luca Risolia"
#define SN9C102_AUTHOR_EMAIL "<luca.risolia@studio.unibo.it>"
#define SN9C102_MODULE_LICENSE "GPL"
#define SN9C102_MODULE_VERSION "1:1.44"
#define SN9C102_MODULE_VERSION_CODE KERNEL_VERSION(1, 1, 44)
#define SN9C102_MODULE_VERSION "1:1.47"
#define SN9C102_MODULE_VERSION_CODE KERNEL_VERSION(1, 1, 47)

/*****************************************************************************/

Expand All @@ -64,9 +64,10 @@ MODULE_LICENSE(SN9C102_MODULE_LICENSE);
static short video_nr[] = {[0 ... SN9C102_MAX_DEVICES-1] = -1};
module_param_array(video_nr, short, NULL, 0444);
MODULE_PARM_DESC(video_nr,
"\n<-1|n[,...]> Specify V4L2 minor mode number."
"\n -1 = use next available (default)"
"\n n = use minor number n (integer >= 0)"
" <-1|n[,...]>"
"\nSpecify V4L2 minor mode number."
"\n-1 = use next available (default)"
"\n n = use minor number n (integer >= 0)"
"\nYou can specify up to "__MODULE_STRING(SN9C102_MAX_DEVICES)
" cameras this way."
"\nFor example:"
Expand All @@ -79,21 +80,23 @@ static short force_munmap[] = {[0 ... SN9C102_MAX_DEVICES-1] =
SN9C102_FORCE_MUNMAP};
module_param_array(force_munmap, bool, NULL, 0444);
MODULE_PARM_DESC(force_munmap,
"\n<0|1[,...]> Force the application to unmap previously"
" <0|1[,...]>"
"\nForce the application to unmap previously"
"\nmapped buffer memory before calling any VIDIOC_S_CROP or"
"\nVIDIOC_S_FMT ioctl's. Not all the applications support"
"\nthis feature. This parameter is specific for each"
"\ndetected camera."
"\n 0 = do not force memory unmapping"
"\n 1 = force memory unmapping (save memory)"
"\n0 = do not force memory unmapping"
"\n1 = force memory unmapping (save memory)"
"\nDefault value is "__MODULE_STRING(SN9C102_FORCE_MUNMAP)"."
"\n");

static unsigned int frame_timeout[] = {[0 ... SN9C102_MAX_DEVICES-1] =
SN9C102_FRAME_TIMEOUT};
module_param_array(frame_timeout, uint, NULL, 0644);
MODULE_PARM_DESC(frame_timeout,
"\n<0|n[,...]> Timeout for a video frame in seconds before"
" <0|n[,...]>"
"\nTimeout for a video frame in seconds before"
"\nreturning an I/O error; 0 for infinity."
"\nThis parameter is specific for each detected camera."
"\nDefault value is "__MODULE_STRING(SN9C102_FRAME_TIMEOUT)"."
Expand All @@ -103,7 +106,8 @@ MODULE_PARM_DESC(frame_timeout,
static unsigned short debug = SN9C102_DEBUG_LEVEL;
module_param(debug, ushort, 0644);
MODULE_PARM_DESC(debug,
"\n<n> Debugging information level, from 0 to 3:"
" <n>"
"\nDebugging information level, from 0 to 3:"
"\n0 = none (use carefully)"
"\n1 = critical errors"
"\n2 = significant informations"
Expand Down Expand Up @@ -1616,7 +1620,8 @@ static int sn9c102_init(struct sn9c102_device* cam)
int err = 0;

if (!(cam->state & DEV_INITIALIZED)) {
init_waitqueue_head(&cam->open);
mutex_init(&cam->open_mutex);
init_waitqueue_head(&cam->wait_open);
qctrl = s->qctrl;
rect = &(s->cropcap.defrect);
} else { /* use current values */
Expand Down Expand Up @@ -1706,65 +1711,106 @@ static int sn9c102_init(struct sn9c102_device* cam)
return 0;
}

/*****************************************************************************/

static void sn9c102_release_resources(struct sn9c102_device* cam)
static void sn9c102_release_resources(struct kref *kref)
{
struct sn9c102_device *cam;

mutex_lock(&sn9c102_sysfs_lock);

cam = container_of(kref, struct sn9c102_device, kref);

DBG(2, "V4L2 device /dev/video%d deregistered", cam->v4ldev->minor);
video_set_drvdata(cam->v4ldev, NULL);
video_unregister_device(cam->v4ldev);
usb_put_dev(cam->usbdev);
kfree(cam->control_buffer);
kfree(cam);

mutex_unlock(&sn9c102_sysfs_lock);

kfree(cam->control_buffer);
}

/*****************************************************************************/

static int sn9c102_open(struct inode* inode, struct file* filp)
{
struct sn9c102_device* cam;
int err = 0;

/*
This is the only safe way to prevent race conditions with
disconnect
A read_trylock() in open() is the only safe way to prevent race
conditions with disconnect(), one close() and multiple (not
necessarily simultaneous) attempts to open(). For example, it
prevents from waiting for a second access, while the device
structure is being deallocated, after a possible disconnect() and
during a following close() holding the write lock: given that, after
this deallocation, no access will be possible anymore, using the
non-trylock version would have let open() gain the access to the
device structure improperly.
For this reason the lock must also not be per-device.
*/
if (!down_read_trylock(&sn9c102_disconnect))
if (!down_read_trylock(&sn9c102_dev_lock))
return -ERESTARTSYS;

cam = video_get_drvdata(video_devdata(filp));

if (mutex_lock_interruptible(&cam->dev_mutex)) {
up_read(&sn9c102_disconnect);
if (wait_for_completion_interruptible(&cam->probe)) {
up_read(&sn9c102_dev_lock);
return -ERESTARTSYS;
}

kref_get(&cam->kref);

/*
Make sure to isolate all the simultaneous opens.
*/
if (mutex_lock_interruptible(&cam->open_mutex)) {
kref_put(&cam->kref, sn9c102_release_resources);
up_read(&sn9c102_dev_lock);
return -ERESTARTSYS;
}

if (cam->state & DEV_DISCONNECTED) {
DBG(1, "Device not present");
err = -ENODEV;
goto out;
}

if (cam->users) {
DBG(2, "Device /dev/video%d is busy...", cam->v4ldev->minor);
DBG(2, "Device /dev/video%d is already in use",
cam->v4ldev->minor);
DBG(3, "Simultaneous opens are not supported");
/*
open() must follow the open flags and should block
eventually while the device is in use.
*/
if ((filp->f_flags & O_NONBLOCK) ||
(filp->f_flags & O_NDELAY)) {
err = -EWOULDBLOCK;
goto out;
}
mutex_unlock(&cam->dev_mutex);
err = wait_event_interruptible_exclusive(cam->open,
cam->state & DEV_DISCONNECTED
DBG(2, "A blocking open() has been requested. Wait for the "
"device to be released...");
up_read(&sn9c102_dev_lock);
/*
We will not release the "open_mutex" lock, so that only one
process can be in the wait queue below. This way the process
will be sleeping while holding the lock, without loosing its
priority after any wake_up().
*/
err = wait_event_interruptible_exclusive(cam->wait_open,
(cam->state & DEV_DISCONNECTED)
|| !cam->users);
if (err) {
up_read(&sn9c102_disconnect);
return err;
}
down_read(&sn9c102_dev_lock);
if (err)
goto out;
if (cam->state & DEV_DISCONNECTED) {
up_read(&sn9c102_disconnect);
return -ENODEV;
err = -ENODEV;
goto out;
}
mutex_lock(&cam->dev_mutex);
}


if (cam->state & DEV_MISCONFIGURED) {
err = sn9c102_init(cam);
if (err) {
Expand All @@ -1789,36 +1835,33 @@ static int sn9c102_open(struct inode* inode, struct file* filp)
DBG(3, "Video device /dev/video%d is open", cam->v4ldev->minor);

out:
mutex_unlock(&cam->dev_mutex);
up_read(&sn9c102_disconnect);
mutex_unlock(&cam->open_mutex);
if (err)
kref_put(&cam->kref, sn9c102_release_resources);

up_read(&sn9c102_dev_lock);
return err;
}


static int sn9c102_release(struct inode* inode, struct file* filp)
{
struct sn9c102_device* cam = video_get_drvdata(video_devdata(filp));
struct sn9c102_device* cam;

mutex_lock(&cam->dev_mutex); /* prevent disconnect() to be called */
down_write(&sn9c102_dev_lock);

sn9c102_stop_transfer(cam);
cam = video_get_drvdata(video_devdata(filp));

sn9c102_stop_transfer(cam);
sn9c102_release_buffers(cam);

if (cam->state & DEV_DISCONNECTED) {
sn9c102_release_resources(cam);
usb_put_dev(cam->usbdev);
mutex_unlock(&cam->dev_mutex);
kfree(cam);
return 0;
}

cam->users--;
wake_up_interruptible_nr(&cam->open, 1);
wake_up_interruptible_nr(&cam->wait_open, 1);

DBG(3, "Video device /dev/video%d closed", cam->v4ldev->minor);

mutex_unlock(&cam->dev_mutex);
kref_put(&cam->kref, sn9c102_release_resources);

up_write(&sn9c102_dev_lock);

return 0;
}
Expand Down Expand Up @@ -2085,7 +2128,6 @@ static int sn9c102_mmap(struct file* filp, struct vm_area_struct *vma)

vma->vm_ops = &sn9c102_vm_ops;
vma->vm_private_data = &cam->frame[i];

sn9c102_vm_open(vma);

mutex_unlock(&cam->fileop_mutex);
Expand Down Expand Up @@ -3215,8 +3257,6 @@ sn9c102_usb_probe(struct usb_interface* intf, const struct usb_device_id* id)
goto fail;
}

mutex_init(&cam->dev_mutex);

r = sn9c102_read_reg(cam, 0x00);
if (r < 0 || (r != 0x10 && r != 0x11 && r != 0x12)) {
DBG(1, "Sorry, this is not a SN9C1xx-based camera "
Expand Down Expand Up @@ -3282,7 +3322,7 @@ sn9c102_usb_probe(struct usb_interface* intf, const struct usb_device_id* id)
cam->v4ldev->release = video_device_release;
video_set_drvdata(cam->v4ldev, cam);

mutex_lock(&cam->dev_mutex);
init_completion(&cam->probe);

err = video_register_device(cam->v4ldev, VFL_TYPE_GRABBER,
video_nr[dev_nr]);
Expand All @@ -3292,7 +3332,7 @@ sn9c102_usb_probe(struct usb_interface* intf, const struct usb_device_id* id)
DBG(1, "Free /dev/videoX node not found");
video_nr[dev_nr] = -1;
dev_nr = (dev_nr < SN9C102_MAX_DEVICES-1) ? dev_nr+1 : 0;
mutex_unlock(&cam->dev_mutex);
complete_all(&cam->probe);
goto fail;
}

Expand All @@ -3318,8 +3358,10 @@ sn9c102_usb_probe(struct usb_interface* intf, const struct usb_device_id* id)
#endif

usb_set_intfdata(intf, cam);
kref_init(&cam->kref);
usb_get_dev(cam->usbdev);

mutex_unlock(&cam->dev_mutex);
complete_all(&cam->probe);

return 0;

Expand All @@ -3336,40 +3378,31 @@ sn9c102_usb_probe(struct usb_interface* intf, const struct usb_device_id* id)

static void sn9c102_usb_disconnect(struct usb_interface* intf)
{
struct sn9c102_device* cam = usb_get_intfdata(intf);

if (!cam)
return;
struct sn9c102_device* cam;

down_write(&sn9c102_disconnect);
down_write(&sn9c102_dev_lock);

mutex_lock(&cam->dev_mutex);
cam = usb_get_intfdata(intf);

DBG(2, "Disconnecting %s...", cam->v4ldev->name);

wake_up_interruptible_all(&cam->open);

if (cam->users) {
DBG(2, "Device /dev/video%d is open! Deregistration and "
"memory deallocation are deferred on close.",
"memory deallocation are deferred.",
cam->v4ldev->minor);
cam->state |= DEV_MISCONFIGURED;
sn9c102_stop_transfer(cam);
cam->state |= DEV_DISCONNECTED;
wake_up_interruptible(&cam->wait_frame);
wake_up(&cam->wait_stream);
usb_get_dev(cam->usbdev);
} else {
} else
cam->state |= DEV_DISCONNECTED;
sn9c102_release_resources(cam);
}

mutex_unlock(&cam->dev_mutex);
wake_up_interruptible_all(&cam->wait_open);

if (!cam->users)
kfree(cam);
kref_put(&cam->kref, sn9c102_release_resources);

up_write(&sn9c102_disconnect);
up_write(&sn9c102_dev_lock);
}


Expand Down
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