On Thu, Nov 24, 2011 at 11:12 AM, Amit Nagal <helloin.amit@xxxxxxxxx> wrote:
>>
>
> (1 ) Hi , to test this , in one terminal , i continously read usb
> audio interface ( /dev/dsp1) in a while loop ,
> and in another terminal , i reset the usb device via a userspace program .
> At the time of reset , read(/dev/dsp1) failed with error : : Broken pipe .
>
> (2) Now , on linux machine , once read(/dev/dsp1) failed , i needed a
> minimum of 150 ms delay before i can reopen
> /dev/dsp1 successfully . if i donot provide this 150 ms delay , test
> program fails to re-open /dev/dsp1 ,
> and in dmesg i could see a line 0:1:1: usb_set_interface failed .
>
Very Sorry , my mistake . As pointed in other mail , once
read(/dev/dsp1) fails at usb reset , next open of /dev/dsp1 is success
immediately . but the ioctl SNDCTL_DSP_CHANNELS keeps on failing with
i/o error for about 110 ms .
i enclose my userspace program log also below :
( len = data len read , i read 8k every time )
cnt=[58] len = 0x2000 8192
cnt=[59] len = 0x54 84
==================read error=================: Broken pipe
========= CLOSING DEVICE==========
file opened successfully
ioctl : SNDCTL_DSP_CHANNELS - fail
: Input/output error
.........
========= CLOSING DEVICE==========
file opened successfully
ioctl : SNDCTL_DSP_CHANNELS - success
ioctl - SNDCTL_DSP_SPEED - success - temp=0xac44
ioctl - SNDCTL_DSP_SETFMT - success - temp = 0x10
cnt=[60] len = 0x2000 8192
cnt=[61] len = 0x2000 8192
2) here is userspace test program :
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/soundcard.h>
#include <sys/ioctl.h>
int main(void)
{
int fd ;
unsigned char buff[8192*2];
int buff_len , i ;
int ret , temp ;
unsigned int read_count = 0 ;
ipod_retry : fd = open("/dev/dsp1" , O_RDWR);
if(fd == -1)
{
printf("cannot open /dev/dsp \n");
goto ipod_retry ;
}
else
{
printf("file opened successfully\n");
}
temp = 2 ;
ret = ioctl(fd , SNDCTL_DSP_CHANNELS , &temp );
if(ret == -1 )
{
perror("ioctl : SNDCTL_DSP_CHANNELS - fail\n");
goto close_ipod_fd ;
}
else
{
printf("ioctl : SNDCTL_DSP_CHANNELS - success \n");
}
temp = 44100 ;
ret = ioctl(fd , SNDCTL_DSP_SPEED , &temp );
if(ret == -1 )
{
perror("ioctl : SNDCTL_DSP_SPEED - fail \n");
goto close_ipod_fd ;
}
else
{
printf("ioctl - SNDCTL_DSP_SPEED - success - temp=0x%x\n" , temp );
temp = AFMT_S16_LE ;
ret = ioctl(fd , SNDCTL_DSP_SETFMT , &temp );
if(ret == -1 )
{
perror("ioctl : SNDCTL_DSP_SETFMT - fail \n");
goto close_ipod_fd ;
}
else
{
printf("ioctl - SNDCTL_DSP_SETFMT - success - temp = 0x%x\n" , temp );
}
}
while(1)
{
buff_len = read(fd , buff , 8192 ) ;
if(buff_len == -1 ){
perror("==================read error=================");
goto close_ipod_fd ;
}
else{
printf("\ncnt=[%u] len = 0x%x %d\n\n" , ++read_count , buff_len ,
buff_len );
}
}
close_ipod_fd : printf("\n========= CLOSING DEVICE==========\n");
close(fd);
goto ipod_retry ;
return 0 ;
}
Thanx & Regards
Amit Nagal
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