Hello,
t am trying to create native driver for subj. I used dx200.c as my
inspiration. Everything is working fine for me but !!!!!!
When i connect camera & power up driver is initialized thru probe function
and new device major/minor (180/96) is added to the system. So i decide
make a simple test. I wrote simple userspace program which tries open new
device ( i made node in /dev for it using mknod of course ). In this code i
only use fopen and fclose.
Fisrt time when i run user space program it looks ok. fopen succed file
handle pointer is not NULL !! But function fclose which is called after fopen
fails !!! and in syslog appears folowing message : Sep 16 12:46:24 ak47
kernel: VFS: Close: file count is 0 . Next time when i try to execute same
code it fails on fopen with SIGSEGV. What i am doing wrong ? Any suggestions ?
Thanx & Bye Sam
static int canon_camera_open(struct inode *inode,struct file *file) {
struct canon_camera_state *camera = NULL;
int value;
int subminor;
MOD_INC_USE_COUNT;
down( &state_table_mutex );
subminor = MINOR(inode->i_rdev) - USB_CAMERA_MINOR_BASE;
if ( subminor <0 || subminor > MAX_CAMERAS ||
!(camera=minor_data[subminor])) {
up( &state_table_mutex );
MOD_DEC_USE_COUNT;
return -ENODEV;
}
down( &camera->sem );
up( &state_table_mutex );
if ( camera->buffer ) {
MOD_DEC_USE_COUNT;
value = -EBUSY;
goto done;
}
if (!(camera->buffer = (char *)kmalloc (MAX_PACKET_SIZE,GFP_KERNEL))) {
MOD_DEC_USE_COUNT;
value = -ENOMEM;
goto done;
}
dbg("open %d",subminor);
file->private_data = camera;
done:
up( &camera->sem );
return value;
}
My configuration:
Kernel 2.4.9 on RH7.1 Toshiba Statellite Pro 43000 series with 192MB Ram.
Syslog:
Sep 16 12:31:48 ak47 kernel: usb.c: registered new driver cpwsa20
Sep 16 12:31:48 ak47 kernel: cpwsa20.c: v0.0.1:USB Camera Driver for Canon
Powershot A20
Sep 16 12:33:23 ak47 kernel: hub.c: USB new device connect on bus1/1,
assigned device number 2
Sep 16 12:33:23 ak47 kernel: Manufacturer: Canon Inc.
Sep 16 12:33:23 ak47 kernel: Product: PowerShot A20
Sep 16 12:33:23 ak47 kernel: cpwsa20.c: Numconf=1, NumInterfaces=1
Sep 16 12:33:23 ak47 kernel: cpwsa20.c: Class=255, Subclass=255, Endpoints=3
Sep 16 12:33:23 ak47 kernel: cpwsa20.c: inEP=1, outEP=2, miscEP=3
Sep 16 12:33:23 ak47 kernel: cpwsa20.c: USB camera #0 coneceted, major/minor
180/96
Sep 16 12:33:23 ak47 /sbin/hotplug: arguments (usb) env (PWD=/etc/hotplug
HOSTNAME=ak47 DEVICE=/proc/bus/usb/001/002 ACTION=add DEBUG=kernel
MACHTYPE=i386-redhat-linux-gnu OLDPWD=/ DEVFS=/proc/bus/usb TYPE=255/255/255
SHLVL=1 SHELL=/bin/bash HOSTTYPE=i386 OSTYPE=linux-gnu HOME=/ TERM=dumb
PATH=/bin:/sbin:/usr/sbin:/usr/bin PRODUCT=4a9/304e/1 _=/usr/bin/env)
Sep 16 12:33:23 ak47 /sbin/hotplug: invoke /etc/hotplug/usb.agent
Sep 16 12:33:23 ak47 /etc/hotplug/usb.agent: Modprobe and setup cpwsa20 for
USB product 4a9/304e/1
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