Re: "Fix ATAPI transfer lengths" causes CD writing regression

Daniel Drake
2007-10-30T17:46:23Z

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Alan Cox wrote:
> Not immediately - but if you've got wrong transfer lengths its a
> candidate for this.
>
> Ok lets start with the basics
>
> If you mount a CD and use it does it work

Yep.

> If you use cdrecord does it work ?

Yep (tested with wodim from debburn, effectively the same thing)

> What vendor drive and does it seem to be a specific box/drive that
> triggers this ?

Device type : Removable CD-ROM
Version : 5
Response Format: 2
Capabilities :
Vendor_info : 'PHILIPS '
Identification : 'DVD+-RW SDVD8820'
Revision : 'AD15'
Device seems to be: Generic mmc2 DVD-R/DVD-RW.
Using generic SCSI-3/mmc CD-R/CD-RW driver (mmc_cdr).
Driver flags : MMC-3 SWABAUDIO BURNFREE
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P RAW/R96R

This is on my laptop (Dell Inspiron 640m). I won't have access to
another system to test this there until next week.

The nutty app I was using for burning is Brasero, a GNOME app which does
some SG_IO directly with the drive. (I guess it has some bad error
handling and doesn't realise when some I/O path has failed)

I have narrowed down the exact command submission which causes those
nasty messages in dmesg. The function which submits this is named
"brasero_medium_get_page_2A_write_speed_desc".

The test program that I've attached can now reproduce this error every
time it is run. The output is:

result 0
check sense data:
72 0b 47 00 00 00 00 0e 09 0c 00 00 00 02 00 00 00 0a 00

I get the same output and dmesg errors even when there is no media in
the drive.

I have had a quick look at the SCSI command being submitted there, and
don't see anything wrong.

What next?

Daniel

[-- Attachment #2: testsg.c --]
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#include <stdio.h>
#include <scsi/sg.h>
#include <scsi/scsi.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(void)
{
struct sg_io_hdr transport;
unsigned char cmd[] = {
0x5a, //opcode -- mode sense(10)
0x08, //dbd, llbaa -- dbd=1
0x2a, //page code -- BRASERO_SPC_PAGE_STATUS
// spc-3 says thats "CD capabilities and mechanical status"
//
0x00, //brasero says reserved, spc3 says subpage code
0x00, //reserved
0x00, //reserved
0x00, //alloc len
0x0a, //alloc len
0x00, //ctl
};
unsigned char buffer[10];
unsigned char sense_data[19];
int r;
int i;
int fd = open("/dev/sr0", O_RDONLY|O_NONBLOCK);
if (fd < 0) {
printf("open failed\n");
exit(1);
}

memset(&transport, 0, sizeof(transport));
memset(buffer, 0, sizeof(buffer));
memset(sense_data, 0, sizeof(sense_data));

transport.interface_id = 'S';
transport.cmdp = cmd;
transport.cmd_len = sizeof(cmd);
transport.dxferp = buffer;
transport.dxfer_len = sizeof(buffer);
transport.sbp = sense_data;
transport.mx_sb_len = sizeof(sense_data);
transport.dxfer_direction = SG_DXFER_FROM_DEV;

r = ioctl(fd, SG_IO, &transport);
printf("result %d\n", r);
if ((transport.masked_status & CHECK_CONDITION) && transport.sb_len_wr) {
printf("check sense data:\n");
for (i = 0; i < sizeof(sense_data); i++)
printf("%02x ", sense_data[i]);
printf("\n");
}
}