This message is from the T13 list server.
On Tue, 11 Nov 2003 20:50:40 +0900, [EMAIL PROTECTED] wrote: >This message is from the T13 list server. >About 1) >ATA/ATAPI specification does not allow any time-out of device interface. So >if data transfer direction is incorrect, it hangs up. It *may* hang. In MW DMA many devices see any IOR-/IOW- assertion as a valid transfer of data without paying attention to what is on the Data bus. This means the command may complete with neither the host or device knowing that there was a direction mismatch. I am happy to say that U-DMA does not have this problem. >Unfortunately, OS driver/software shows incorrect data transfer direction >to PATA in some cases. This causes problem in P1394/USB-ATAPI bridge board >actually. SATA-PATA bridge should have some knowledge of SCSI ope-code too. I would say far more ATAPI devices set IO and CD wrong than there are hosts that use the wrong transfer direction for a command. >This protocol is valid between OS driver/software and SATA-PATA bridge. >Current ATAPI ODD never mind DMADIR bit. This means SATA-PATA bridge should >modify the ATAPI Identify Device data. ? How does it work now? I was going to ask this question too... Thanks for asking it. This proposal should be written such that it will work for a bridge that modifies the ID data on-the-fly. This also means the bridge must turn off the DMADIR bit in the Features register so an older device doesn't see it. However, I really would like to know how the bridge will know the difference between the FR value used with SET FEATURES from the FR value used with a PACKET command - this means the bridge must look at the command code and command parameters before sending them on to the device. This isn't a kludge - it is a HUGE KLUDGE!!! Hale *** Hale Landis *** www.ata-atapi.com ***
