On Thu, 1 Apr 2010, Hrant Dalalyan wrote: > Implementation of USB Attached SCSI Protocol per UASP Specification > (Rev.1, July 9, 2008). Below is the list of the enhancements made to > the usb-storage driver. In my opinion the UAS protocol is so different from the older USB mass-storage protocols (it has almost nothing in common) that you'd be better off writing a whole new driver instead of grafting this stuff onto usb-storage. > - Enhanced probe routine to identify UASP devices. > - Allocation/deallocation of UASP specific resources. > - Various enhancements to existing infrastructure to invoke UASP > specific routines. > - Added SCSI command queueing mechanism and state machine for > handling multiple commands. > - Implemented 'abort task' and 'reset nexus' task management > functions. None of this should clutter up the usb-storage driver. That's part of the reason why an entirely new driver would be better. > Limitations: > > - Considered that the endpoint descriptors are received from the device > side in the following order: > - Command endpoint descriptor. > - Bulk in endpoint descriptor. > - Bulk out endpoint descriptor. > - Status endpoint descriptor. > because in the noted revision of the UASP Specification were not defined > pipe usage descriptors. They are defined in Revision 2 (March 21, 2009 -- I can send you a copy if you can't find it). You should use them. > - The max number of streams are not retrieved through the superspeed > endpoint companion descriptor and are fixed to 2 streams per > endpoint. Why not use the descriptor? > - Device supported LUNs are assumed to be 1. > - Concurrent processing of SCSI commands is not yet tested due to due > to some device limitations. The driver is currently set to process > only 1 command at a time. > - Abort task, Reset nexus task management functions, as well as some > error conditions and recovery situations are not yet tested. These limitations should be removed as quickly as possible. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
