Mailinglist Archive: opensuse-amd64 (302 mails)

[Bernd Paysan <bernd.paysan@xxxxxx>]

Hi,

One of my USB storage devices fails after 64k read (when copying files)  
with an IO error (the device worked fine with previous SuSEs, works 
with Windows, too, but I did see a similar problem on a Debian  
distribution). It's a Mambo-X USB MP3 stick, which reports an Atmel ID  
(so the driver chip is from Atmel). Writing is ok, and it plays all  
written files well, so the device itself is "ok" (it also can play 
files with anoraK). The other USB  storage devices I've attached so far 
work well.

I turned on USB storage verbose debug support, recompiled the kernel,  
and looked at the output. The highly suspect entry is:

Jan  6 00:40:14 vimes kernel: usb-storage: Bulk Status S 0x53425355 T 
0x2a556 R 65536 Stat 0x0
          ^^^^^

This certainly should be 0 (all other entries indicate that the transfer  
was ok). For all other sizes <64k, it *is* 0, as it should be. Faking  
the residual to 0 when it is reportedly longer fixes all problems (see  
attached patch, against the SuSE 9.2 2.6.8-24.10 kernel, x86_64 
version).

The source of the problem is obviously buggy code inside the device  
itself, i.e. it subtracts the residual using a 16 bit counter only. 
This explains nicely why it works with Windows (that just doesn't do 
>=64k SCSI reads ;-).

This bad hack "fixes" my problem, but it's not a real solution. It is  
probably better to be able to restrict certain USB storage devices 
(specifically this one ;-) to less than 64k transfers, or at least 
check for this ID when doing the hack (the transfer itself is ok, just 
the reported bytes are not). The device ID is (from lsusb)

Bus 004 Device 002: ID 03eb:2002 Atmel Corp.

-- 
Bernd Paysan
"If you want it done right, you have to do it yourself"
http://www.jwdt.com/~paysan/
--- linux-2.6.8-24.10/drivers/usb/storage/transport.c.orig	2005-01-06 00:52:32.283149967 +0100
+++ linux-2.6.8-24.10/drivers/usb/storage/transport.c	2005-01-06 00:52:58.935858513 +0100
@@ -1055,6 +1055,8 @@
 
 	/* try to compute the actual residue, based on how much data
 	 * was really transferred and what the device tells us */
+	if(residue = 0x10000)
+	  residue = 0; // fake residue to 0
 	residue = min(residue, transfer_length);
 	srb->resid = max(srb->resid, (int) residue);