On Thu, 2004-04-08 at 13:33, Alan Stern wrote: > On Thu, 8 Apr 2004, Matt Gulick wrote: > > > OK, Silly question or maybe not. > > > > When writing drivers for MacOS ( 7-9 & X) and Windose (98 - XP) and > when > > I architected the USB 2.0 stack at Adaptec for 98SE, ME & 2k, we > solved > > this issue with a simple heart beat task. > > > > Every so often (1-3 seconds) any device that was at risk of removal > > would receive a TEST UNIT READY cdb. > > > > Using the model of 1394, USB, ... being treated as a device with no > > media inserted (like a CD drive is treated), then you can query the > > device for media availability. > > > > Using the USB model of 7 tiers of devices and most hubs having 4 > ports > > (7 port hubs are just two 4 port hubs internally connected) you can > have > > way more than 15 SCSI ID's. By treating each USB as having its own > ID > > (EHCI USB chips typically have three USB identities of 1 EHCI and 2 > OHCI > > interfaces) and the devices on that bus that are mass storage class > > devices using SBP-2 or SBP-3 would be a LUN on that device. > > > > By treating each bus as a virtual device, the main struct can be > static > > with LUN children added or removed as needed. > > > > Any thoughts on this? > > > > Matt > > I think you're talking about a different problem. Sending heartbeats > solves the problem of detecting media availability and device > availability. It doesn't solve the problem we're discussing here, > which > is how to tear down the device driver stack without causing any > errors, > particularly if the user tries to access the device while the stack is > being deconstructed. > > Alan Stern
True. This only mitigates the need for the SCSI subsystem from having to release device structures that might be used for logical SCSI Bus housekeeping. I will have to dig into the Linux architecture model for SCSI to put this in Linux form vs what is done elsewhere. I'll be back. ;-) Matt ---------------------------------------- Matt Gulick Sr. Staff Engineer Adaptec, Inc. [EMAIL PROTECTED] [EMAIL PROTECTED] (715) 426-0884 ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
