Re: [linux-usb-devel] Re: Problems with connect/disconnect cycles

[Alan Stern]

On Sun, 21 Aug 2005, Norbert Preining wrote:

> Hi USB developers, hi Andrew!
> 
> On Mon, 21 Mär 2005, preining wrote:
> > Dear usb developers, dear Andrew!
> > 
> > I found that my builtin sd card reader connected via USB port
> > experiences several connect/reconnect cycles every time I boot.
> > 
> > I am using 2.6.11-mm4.
> 
> Same now with 2.6.13-rc6-mm1. This time it got really bad:
> 
> Aug 20 14:00:19 gandalf vmunix: usb 2-2: USB disconnect, address 2
> Aug 20 14:00:19 gandalf kernel: usb 2-2: new full speed USB device using uhci_hcd and address 3
> Aug 20 14:00:19 gandalf kernel: scsi1 : SCSI emulation for USB Mass Storage devices
> Aug 20 14:00:19 gandalf kernel: usb-storage: device found at 3
> Aug 20 14:00:19 gandalf kernel: usb-storage: waiting for device to settle before scanning
> Aug 20 14:00:21 gandalf usb.agent[6109]:      usb-storage: already loaded
> Aug 20 14:00:24 gandalf vmunix:   Vendor: Generic   Model: Flash R/W         Rev: 2002
> Aug 20 14:00:24 gandalf vmunix:   Type:   Direct-Access                      ANSI SCSI revision: 02
> Aug 20 14:00:24 gandalf vmunix: Attached scsi removable disk sda at scsi1, channel 0, id 0, lun 0
> Aug 20 14:00:24 gandalf kernel: usb-storage: device scan complete
> Aug 20 14:00:26 gandalf scsi.agent[6154]:      sd_mod: loaded successfully (for disk)

> Unfortunately I cannot in any way track down this problem to specific
> kernels, or specific work situations. It sometimes happens, sometimes
> not. 
> 
> If anyone has any idea how to debug such a stupid problem, I would be
> glad. 

Speaking in broad terms, it's normal to see new device connection and
configuration messages like the ones above when a USB device is plugged in
to your computer.  What's not normal is to see disconnects.  So you should
be concentrating on what happens just before the log entries you posted --
why is the card reader disconnecting?  Turning on CONFIG_USB_DEBUG may 
provide more help.

Alan Stern

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