** This is the quasi-official and semi-temporary T13 email list server. ** Hale, Back in ATA/ATAPI-4 the Id-Drive word-0 for packet devices had defined bits 5 & 6 such that a packet device could report that it will assert INTRQ after the packet command is sent and before the packet was actually sent. I've seen these devices and must support them since they are the ones setting INTRQ. How does this play into this mess? Regards, MKE. -----Original Message----- From: Hale Landis [mailto:[EMAIL PROTECTED]] Sent: Sunday, September 09, 2001 10:37 AM To: Ooi, Thien Ern; [EMAIL PROTECTED] Subject: [temp t13] Re: PACKET DMA clarification ** This is the quasi-official and semi-temporary T13 email list server. ** On Sat, 8 Sep 2001 23:15:49 -0700, Ooi, Thien Ern wrote: >I would like to clarify just exactly what conditions cause the device to >assert an interrupt prior to a dma data transfer for a PACKET dma command. >The device state in question is DPD3 "Ready_INTRQ" in the device PACKET-DMA >command state diagram. Please be very careful... There is an ERROR in the ATA/ATAPI-5 state diagrams for PACKET DMA. This error should be fixed in the ATA/ATAPI-5 "Errata" document and it should be fixed in the ATA/ATAPI-6 state diagrams. An ATAPI device executing a PACKET command in DMA mode should assert interrupt only ONCE during the PACKET command executiong and that is at the very end of the PACKET command execution. >In T13/1321D revision 3, it shows that the device will enter the DPD3 state, >and assert the interrupt when it is "ready to transfer data and nIEN=0". >However, in T13/1410D revision 1c, this transition has been _removed_. ATA/ATAPI-5 is wrong. ATA/ATAPI-6 is correct. You are not the only ATAPI device designer that has been mislead by this error in the state diagrams. *** Hale Landis *** [EMAIL PROTECTED] *** *** Niwot, CO USA *** www.ata-atapi.com *** -- If you have any questions or wish to unsubscribe send a message to Hale Landis, [EMAIL PROTECTED] To post to this list server send your message to [EMAIL PROTECTED] For questions concerning Thistle Grove Industries or TGI's list services please send email to [EMAIL PROTECTED] -- If you have any questions or wish to unsubscribe send a message to Hale Landis, [EMAIL PROTECTED] To post to this list server send your message to [EMAIL PROTECTED] For questions concerning Thistle Grove Industries or TGI's list services please send email to [EMAIL PROTECTED]
