cdrom blocksize reset bug with 2.4.x kernels

cdrom blocksize reset bug with 2.4.x kernels

[Attila Kinali]

[-- Attachment #1: Type: text/plain, Size: 1212 bytes --]

Hi,

After some discussion on the mplayer-users mailinglist about
that for some scsi drives it's impossible to read a data cd
after reading a vcd/scvd until the next reboot.
(see http://mplayerhq.hu/pipermail/mplayer-users/2002-December/025696.html)

I found that there is a reset of the cdrom block size needed
for those drives which doesnt restet it themselfs if a new
cd is put in (looks like only a few scsi cdroms are affected)

Attached is a small patch for drivers/cdrom/cdrom.c that fixes 
this for the 2.4.20 kernel (and also for 2.4.21 as the code didn't
change). It's reseting the blocksize when a cdrom is opened for
the first time (meaning that a umount/mount cycle can reset
the blocksize).

I run this code now for about half a year and didnt have any problems.
But, as i didnt get any feadback from other people, i'm not sure if
everything is correct.

Greetings
			Attila Kinali

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[-- Attachment #2: cdrom-blocksize.patch --]
[-- Type: application/octet-stream, Size: 509 bytes --]

--- cdrom.c.orig	2003-01-05 15:02:53.000000000 +0100
+++ cdrom.c	2003-01-05 15:05:44.000000000 +0100
@@ -475,7 +475,15 @@
 	else
 		ret = open_for_data(cdi);
 
-	if (!ret) cdi->use_count++;
+	if (!ret)
+	{
+		cdi->use_count++;
+		if(cdi->use_count == 1)
+		{
+			/* reset blocksize in case it's wrong */
+			cdrom_switch_blocksize(cdi,CD_FRAMESIZE);
+		}
+	}
 
 	cdinfo(CD_OPEN, "Use count for \"/dev/%s\" now %d\n", cdi->name, cdi->use_count);
 	/* Do this on open.  Don't wait for mount, because they might

Re: cdrom blocksize reset bug with 2.4.x kernels

[Jens Axboe]

On Wed, Jul 02 2003, Attila Kinali wrote:
> Hi,
> 
> After some discussion on the mplayer-users mailinglist about
> that for some scsi drives it's impossible to read a data cd
> after reading a vcd/scvd until the next reboot.
> (see http://mplayerhq.hu/pipermail/mplayer-users/2002-December/025696.html)
> 
> I found that there is a reset of the cdrom block size needed
> for those drives which doesnt restet it themselfs if a new
> cd is put in (looks like only a few scsi cdroms are affected)
> 
> Attached is a small patch for drivers/cdrom/cdrom.c that fixes 
> this for the 2.4.20 kernel (and also for 2.4.21 as the code didn't
> change). It's reseting the blocksize when a cdrom is opened for
> the first time (meaning that a umount/mount cycle can reset
> the blocksize).
> 
> I run this code now for about half a year and didnt have any problems.
> But, as i didnt get any feadback from other people, i'm not sure if
> everything is correct.

If you clean this up wrt coding style, it can go in.

-- 
Jens Axboe

Re: cdrom blocksize reset bug with 2.4.x kernels

[Tobias Diedrich]

As it seems Attila did not write a follow up, I had a look at his patch
and the problem.  The following patch fixes it for me (Plextor PX-32TS).

Please CC me on replies, I am not subscribed to the list.

--- linux-2.4.22/include/linux/cdrom.h	2003-10-28 01:30:34.000000000 +0100
+++ linux/include/linux/cdrom.h	2003-11-09 15:44:20.000000000 +0100
@@ -743,7 +743,8 @@
     	char name[20];                  /* name of the device type */
 /* per-device flags */
         __u8 sanyo_slot		: 2;	/* Sanyo 3 CD changer support */
-        __u8 reserved		: 6;	/* not used yet */
+        __u8 use_read10	: 1;		/* Use READ10 instead of READCD */
+        __u8 reserved		: 5;	/* not used yet */
 	struct cdrom_write_settings write;
 };
 
--- linux-2.4.22/drivers/cdrom/cdrom.c	2003-11-07 23:46:49.000000000 +0100
+++ linux/drivers/cdrom/cdrom.c	2003-11-09 15:52:14.000000000 +0100
@@ -1400,6 +1400,8 @@
 	return 0;
 }
 
+static int cdrom_switch_blocksize(struct cdrom_device_info *cdi, int size);
+
 /*
  * Specific READ_10 interface
  */
@@ -1408,6 +1410,7 @@
 			 int blocksize, int nblocks)
 {
 	struct cdrom_device_ops *cdo = cdi->ops;
+	int ret = 0;
 
 	memset(&cgc->cmd, 0, sizeof(cgc->cmd));
 	cgc->cmd[0] = GPCMD_READ_10;
@@ -1419,7 +1422,22 @@
 	cgc->cmd[7] = (nblocks >>  8) & 0xff;
 	cgc->cmd[8] = nblocks & 0xff;
 	cgc->buflen = blocksize * nblocks;
-	return cdo->generic_packet(cdi, cgc);
+
+	if (blocksize != CD_FRAMESIZE) {
+		ret = cdrom_switch_blocksize(cdi, blocksize);
+		ret |= cdo->generic_packet(cdi, cgc);
+		ret |= cdrom_switch_blocksize(cdi, CD_FRAMESIZE);
+	} else ret = cdo->generic_packet(cdi, cgc);
+
+	/*
+	 * Switch cdrom_read_block back to default behaviour
+	 * if we get an error.
+	 * FIXME: Maybe this should not be done on all errors.
+	 */
+	if (ret != 0)
+		cdi->use_read10 = 0;
+
+	return ret;
 }
 
 /* very generic interface for reading the various types of blocks */
@@ -1428,8 +1446,15 @@
 			    int lba, int nblocks, int format, int blksize)
 {
 	struct cdrom_device_ops *cdo = cdi->ops;
+	int ret;
+
+	if (cdi->use_read10)
+		return cdrom_read_cd(cdi, cgc, lba, blksize, nblocks);
 
 	memset(&cgc->cmd, 0, sizeof(cgc->cmd));
+	/*
+	 * SCSI-II devices are not required to support READ_CD.
+	 */
 	cgc->cmd[0] = GPCMD_READ_CD;
 	/* expected sector size - cdda,mode1,etc. */
 	cgc->cmd[1] = format << 2;
@@ -1452,7 +1477,15 @@
 	default			: cgc->cmd[9] = 0x10;
 	}
 	
-	return cdo->generic_packet(cdi, cgc);
+	ret = cdo->generic_packet(cdi, cgc);
+	if (ret && cgc->sense && cgc->sense->sense_key==0x05 && cgc->sense->asc==0x20 && cgc->sense->ascq==0x00) {
+		ret = cdrom_read_cd(cdi, cgc, lba, blksize, nblocks);
+		if (ret == 0) {
+			cdi->use_read10 = 1;
+			printk(KERN_INFO "cdrom.c: drive does not like READ_CD for blksize=%d, switching to READ_10.\n", blksize);
+		}
+	}
+	return ret;
 }
 
 /* Just about every imaginable ioctl is supported in the Uniform layer
@@ -1956,20 +1989,6 @@
 		cgc.sense = &sense;
 		cgc.data_direction = CGC_DATA_READ;
 		ret = cdrom_read_block(cdi, &cgc, lba, 1, format, blocksize);
-		if (ret && sense.sense_key==0x05 && sense.asc==0x20 && sense.ascq==0x00) {
-			/*
-			 * SCSI-II devices are not required to support
-			 * READ_CD, so let's try switching block size
-			 */
-			/* FIXME: switch back again... */
-			if ((ret = cdrom_switch_blocksize(cdi, blocksize))) {
-				kfree(cgc.buffer);
-				return ret;
-			}
-			cgc.sense = NULL;
-			ret = cdrom_read_cd(cdi, &cgc, lba, blocksize, 1);
-			ret |= cdrom_switch_blocksize(cdi, blocksize);
-		}
 		if (!ret && copy_to_user((char *)arg, cgc.buffer, blocksize))
 			ret = -EFAULT;
 		kfree(cgc.buffer);

-- 
Tobias						PGP: http://9ac7e0bc.2ya.com

Re: cdrom blocksize reset bug with 2.4.x kernels

[Tobias Diedrich]

No comments on this?

I  wrote:
> As it seems Attila did not write a follow up, I had a look at his patch
> and the problem.  The following patch fixes it for me (Plextor PX-32TS).
> 
> Please CC me on replies, I am not subscribed to the list.
> 
> --- linux-2.4.22/include/linux/cdrom.h	2003-10-28 01:30:34.000000000 +0100
> +++ linux/include/linux/cdrom.h	2003-11-09 15:44:20.000000000 +0100
> @@ -743,7 +743,8 @@
>      	char name[20];                  /* name of the device type */
>  /* per-device flags */
>          __u8 sanyo_slot		: 2;	/* Sanyo 3 CD changer support */
> -        __u8 reserved		: 6;	/* not used yet */
> +        __u8 use_read10	: 1;		/* Use READ10 instead of READCD */
> +        __u8 reserved		: 5;	/* not used yet */
>  	struct cdrom_write_settings write;
>  };
>  
> --- linux-2.4.22/drivers/cdrom/cdrom.c	2003-11-07 23:46:49.000000000 +0100
> +++ linux/drivers/cdrom/cdrom.c	2003-11-09 15:52:14.000000000 +0100
> @@ -1400,6 +1400,8 @@
>  	return 0;
>  }
>  
> +static int cdrom_switch_blocksize(struct cdrom_device_info *cdi, int size);
> +
>  /*
>   * Specific READ_10 interface
>   */
> @@ -1408,6 +1410,7 @@
>  			 int blocksize, int nblocks)
>  {
>  	struct cdrom_device_ops *cdo = cdi->ops;
> +	int ret = 0;
>  
>  	memset(&cgc->cmd, 0, sizeof(cgc->cmd));
>  	cgc->cmd[0] = GPCMD_READ_10;
> @@ -1419,7 +1422,22 @@
>  	cgc->cmd[7] = (nblocks >>  8) & 0xff;
>  	cgc->cmd[8] = nblocks & 0xff;
>  	cgc->buflen = blocksize * nblocks;
> -	return cdo->generic_packet(cdi, cgc);
> +
> +	if (blocksize != CD_FRAMESIZE) {
> +		ret = cdrom_switch_blocksize(cdi, blocksize);
> +		ret |= cdo->generic_packet(cdi, cgc);
> +		ret |= cdrom_switch_blocksize(cdi, CD_FRAMESIZE);
> +	} else ret = cdo->generic_packet(cdi, cgc);
> +
> +	/*
> +	 * Switch cdrom_read_block back to default behaviour
> +	 * if we get an error.
> +	 * FIXME: Maybe this should not be done on all errors.
> +	 */
> +	if (ret != 0)
> +		cdi->use_read10 = 0;
> +
> +	return ret;
>  }
>  
>  /* very generic interface for reading the various types of blocks */
> @@ -1428,8 +1446,15 @@
>  			    int lba, int nblocks, int format, int blksize)
>  {
>  	struct cdrom_device_ops *cdo = cdi->ops;
> +	int ret;
> +
> +	if (cdi->use_read10)
> +		return cdrom_read_cd(cdi, cgc, lba, blksize, nblocks);
>  
>  	memset(&cgc->cmd, 0, sizeof(cgc->cmd));
> +	/*
> +	 * SCSI-II devices are not required to support READ_CD.
> +	 */
>  	cgc->cmd[0] = GPCMD_READ_CD;
>  	/* expected sector size - cdda,mode1,etc. */
>  	cgc->cmd[1] = format << 2;
> @@ -1452,7 +1477,15 @@
>  	default			: cgc->cmd[9] = 0x10;
>  	}
>  	
> -	return cdo->generic_packet(cdi, cgc);
> +	ret = cdo->generic_packet(cdi, cgc);
> +	if (ret && cgc->sense && cgc->sense->sense_key==0x05 && cgc->sense->asc==0x20 && cgc->sense->ascq==0x00) {
> +		ret = cdrom_read_cd(cdi, cgc, lba, blksize, nblocks);
> +		if (ret == 0) {
> +			cdi->use_read10 = 1;
> +			printk(KERN_INFO "cdrom.c: drive does not like READ_CD for blksize=%d, switching to READ_10.\n", blksize);
> +		}
> +	}
> +	return ret;
>  }
>  
>  /* Just about every imaginable ioctl is supported in the Uniform layer
> @@ -1956,20 +1989,6 @@
>  		cgc.sense = &sense;
>  		cgc.data_direction = CGC_DATA_READ;
>  		ret = cdrom_read_block(cdi, &cgc, lba, 1, format, blocksize);
> -		if (ret && sense.sense_key==0x05 && sense.asc==0x20 && sense.ascq==0x00) {
> -			/*
> -			 * SCSI-II devices are not required to support
> -			 * READ_CD, so let's try switching block size
> -			 */
> -			/* FIXME: switch back again... */
> -			if ((ret = cdrom_switch_blocksize(cdi, blocksize))) {
> -				kfree(cgc.buffer);
> -				return ret;
> -			}
> -			cgc.sense = NULL;
> -			ret = cdrom_read_cd(cdi, &cgc, lba, blocksize, 1);
> -			ret |= cdrom_switch_blocksize(cdi, blocksize);
> -		}
>  		if (!ret && copy_to_user((char *)arg, cgc.buffer, blocksize))
>  			ret = -EFAULT;
>  		kfree(cgc.buffer);
> 
> -- 
> Tobias						PGP: http://9ac7e0bc.2ya.com

-- 
Tobias						PGP: http://9ac7e0bc.2ya.com
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