Restructure the arbitration loop to allow for reselections that win out over
the adapter's selections. Many fast periferals were getting upset when the sequencer decided to rearbitrate after the device had already won arbitration. This also forced the creation of a list threaded through the SCBs (since we don't have enough space anywhere else) of commands that are awaiting reselection. This list is run down before any new transactions from the input queue are allowed. The list is appened to whenever we begin a selection (simple case since the selecting device is always at the head) and by the kernel driver whenever a request sense occurs. In the common case, the list is only one element long, but when a reselection wins out over a selection and that reselection generates a request sense, the outstanding selection required for the retreval of the sense code grows the list. On machines with many targets, this might cause the list to grow large, so this solution, which will allow up to the maximum number of I/O requests capible of the card elements in the list, was chosen. The list manipulation is trivial and adds three sequencer instructions of overhead to the selection phase. This fixes the "target busy" errors from micropolis drives and the bursty I/O problem when performing I/O between a Quantum Grand Prix and any other device. I anticipate that this will correct many of the problems that have been reported with this driver. Reviewed by: Wcarchive and David Greenman
This commit is contained in:
gibbs
parent
56ee4e4255
commit
59c33f4bae
@ -41,11 +41,12 @@
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#
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##-M#########################################################################
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VERSION AIC7XXX_SEQ_VER "$Id: aic7xxx.seq,v 1.13 1995/04/09 06:40:16 gibbs Exp $"
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VERSION AIC7XXX_SEQ_VER "$Id: aic7xxx.seq,v 1.14 1995/04/15 21:45:56 gibbs Exp $"
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SCBMASK = 0x1f
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SCSISEQ = 0x00
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ENRSELI = 0x10
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SXFRCTL0 = 0x01
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SXFRCTL1 = 0x02
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SCSISIGI = 0x03
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@ -57,7 +58,10 @@ STCNT = 0x08
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STCNT+0 = 0x08
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STCNT+1 = 0x09
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STCNT+2 = 0x0a
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CLRSINT0 = 0x0b
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SSTAT0 = 0x0b
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SELDO = 0x40
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SELDI = 0x20
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CLRSINT1 = 0x0c
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SSTAT1 = 0x0c
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SIMODE1 = 0x11
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@ -138,9 +142,10 @@ SCBARRAY+26 = 0xba
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SCBARRAY+27 = 0xbb
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SCBARRAY+28 = 0xbc
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SCBARRAY+29 = 0xbd
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SCBARRAY+30 = 0xbe
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BAD_PHASE = 0x01 # unknown scsi bus phase
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CMDCMPLT = 0x02
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CMDCMPLT = 0x02 # Command Complete
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SEND_REJECT = 0x11 # sending a message reject
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NO_IDENT = 0x21 # no IDENTIFY after reconnect
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NO_MATCH = 0x31 # no cmd match for reconnect
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@ -164,23 +169,23 @@ ABORT_TAG = 0x91 # Sent an ABORT_TAG message
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# when a WDTR or SDTR message should be sent to the target the SCB's
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# command references.
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#
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# The high bit of DROPATN is set if ATN should be dropped before the ACK
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# when outb is called. REJBYTE contains the first byte of a MESSAGE IN
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# message, so the driver can report an intelligible error if a message is
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# rejected.
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# REJBYTE contains the first byte of a MESSAGE IN message, so the driver
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# can report an intelligible error if a message is rejected.
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#
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# FLAGS's high bit is true if we are currently handling a reselect;
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# its next-highest bit is true ONLY IF we've seen an IDENTIFY message
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# from the reselecting target. If we haven't had IDENTIFY, then we have
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# no idea what the lun is, and we can't select the right SCB register
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# bank, so force a kernel panic if the target attempts a data in/out or
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# command phase instead of corrupting something.
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# command phase instead of corrupting something. FLAGS also contains
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# configuration bits so that we can optimize for TWIN and WIDE controllers
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# as well as the MAX_SYNC bit which we set when we want to negotiate for
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# 10MHz irregardless of what the per target scratch space says.
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#
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# Note that SG_NEXT occupies four bytes.
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#
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SYNCNEG = 0x20
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DROPATN = 0x30
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REJBYTE = 0x31
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DISC_DSB_A = 0x32
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DISC_DSB_B = 0x33
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@ -218,49 +223,77 @@ FLAGS = 0x53 # Device configuration flags
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TWIN_BUS = 0x01
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WIDE_BUS = 0x02
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MAX_SYNC = 0x08
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SENSE = 0x10
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ACTIVE_MSG = 0x20
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IDENTIFY_SEEN = 0x40
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RESELECTED = 0x80
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ACTIVE_A = 0x54
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ACTIVE_B = 0x55
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SAVED_TCL = 0x56
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SAVED_TCL = 0x56 # Temporary storage for the
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# target/channel/lun of a
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# reconnecting target
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# After starting the selection hardware, we return to the "poll_for_work"
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# loop so that we can check for reconnecting targets as well as for our
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# selection to complete just in case the reselection wins bus arbitration.
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# The problem with this is that we must keep track of the SCB that we've
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# already pulled from the QINFIFO and started the selection on just in case
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# the reselection wins so that we can retry the selection at a later time.
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# This problem cannot be resolved by holding a single entry in scratch
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# ram since a reconnecting target can request sense and this will create
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# yet another SCB waiting for selection. The solution used here is to
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# use byte 31 of the SCB as a psuedo-next pointer and to thread a list
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# of SCBs that are awaiting selection. Since 0 is a valid SCB offset,
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# SCB_LIST_NULL is 0x10 which is out of range. The kernel driver must
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# add an entry to this list everytime a request sense occurs. The sequencer
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# will automatically consume the entries.
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WAITING_SCBH = 0x57 # head of list of SCBs awaiting
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# selection
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WAITING_SCBT = 0x58 # tail of list of SCBs awaiting
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# selection
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SCB_LIST_NULL = 0x10
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# Poll QINCNT for work - the lower bits contain
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# the number of entries in the Queue In FIFO.
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#
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start:
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test FLAGS,SENSE jnz start_sense
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start_nosense:
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test WAITING_SCBH,SCB_LIST_NULL jz start_waiting
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poll_for_work:
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test FLAGS,TWIN_BUS jz start2 # Are we a twin channel device?
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# For fairness, we check the other bus first, since we just finished a
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# transaction on the current channel.
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xor SBLKCTL,0x08 # Toggle to the other bus
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test SCSISIGI,0x4 jnz reselect # BSYI
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test SSTAT0,SELDI jnz reselect
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test SSTAT0,SELDO jnz select
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xor SBLKCTL,0x08 # Toggle to the original bus
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start2:
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test SCSISIGI,0x4 jnz reselect # BSYI
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test QINCNT,SCBMASK jz start_nosense
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test SSTAT0,SELDI jnz reselect
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test SSTAT0,SELDO jnz select
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test WAITING_SCBH,SCB_LIST_NULL jz start_waiting
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test QINCNT,SCBMASK jz poll_for_work
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# We have at least one queued SCB now. Set the SCB pointer
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# from the FIFO so we see the right bank of SCB registers,
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# then set SCSI options and set the initiator and target
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# SCSI IDs.
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# We have at least one queued SCB now and we don't have any
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# SCBs in the list of SCBs awaiting selection. Set the SCB
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# pointer from the FIFO so we see the right bank of SCB
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# registers, then set SCSI options and set the initiator and
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# target SCSI IDs.
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#
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mov SCBPTR,QINFIFO
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# If the control byte of this SCB has the NEEDDMA flag set, we have
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# yet to DMA it from host memory
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test SCBARRAY+0,NEEDDMA jz test_busy
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test SCBARRAY+0,NEEDDMA jz test_busy
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clr HCNT+2
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clr HCNT+1
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mvi HCNT+0,SCB_SIZEOF
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mvi DINDEX,HADDR
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mvi SCBARRAY+26 call bcopy_4
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mvi DFCNTRL,0xd # HDMAEN|DIRECTION|FIFORESET
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mvi DINDEX,HADDR
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mvi SCBARRAY+26 call bcopy_4
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mvi DFCNTRL,0xd # HDMAEN|DIRECTION|FIFORESET
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# Wait for DMA from host memory to data FIFO to complete, then disable
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# DMA and wait for it to acknowledge that it's off.
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@ -270,12 +303,12 @@ test SCBARRAY+0,NEEDDMA jz test_busy
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# Copy the SCB from the FIFO to the SCBARRAY
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mvi DINDEX, SCBARRAY+0
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call bcopy_3_dfdat
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call bcopy_3_dfdat
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call bcopy_4_dfdat
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call bcopy_4_dfdat
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call bcopy_4_dfdat
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call bcopy_4_dfdat
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call bcopy_4_dfdat
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# See if there is not already an active SCB for this target. This code
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# locks out on a per target basis instead of target/lun. Although this
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# is not ideal for devices that have multiple luns active at the same
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@ -295,27 +328,35 @@ test_busy:
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or ACTIVE_B,A # Mark the current target as busy
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jmp start_scb
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start_sense:
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# Clear the SENSE flag first, then do a normal start_scb
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and FLAGS,0xef
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jmp start_scb
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# Place the currently active back on the queue for later processing
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requeue:
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mov QINFIFO, SCBPTR
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jmp start_nosense
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jmp poll_for_work
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# Pull the first entry off of the waiting for selection list
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start_waiting:
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mov SCBPTR,WAITING_SCBH
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jmp start_scb
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test_a:
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test ACTIVE_A,A jnz requeue
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or ACTIVE_A,A # Mark the current target as busy
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start_scb:
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or SCBARRAY+0,NEEDDMA
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and SINDEX,0xf7,SBLKCTL #Clear the channel select bit
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and A,0x08,SCBARRAY+1 #Get new channel bit
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or SINDEX,A
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mov SBLKCTL,SINDEX # select channel
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mov SCBARRAY+1 call initialize
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mov SCBARRAY+1 call initialize_scsiid
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# Enable selection phase as an initiator, and do automatic ATN
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# after the selection. We do this now so that we can overlap the
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# rest of our work to set up this target with the arbitration and
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# selection bus phases.
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#
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start_selection:
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or SCSISEQ,0x48 # ENSELO|ENAUTOATNO
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mov WAITING_SCBH, SCBPTR
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clr SG_NOLOAD
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and FLAGS,0x3f # !RESELECTING
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@ -355,61 +396,30 @@ mk_tag_done:
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mov DINDEX call mk_dtr # build DTR message if needed
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!message:
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jmp poll_for_work
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# Enable selection phase as an initiator, and do automatic ATN
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# after the selection.
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#
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mvi SCSISEQ,0x48 # ENSELO|ENAUTOATNO
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# Wait for successful arbitration. The AIC-7770 documentation says
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# that SELINGO indicates successful arbitration, and that it should
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# be used to look for SELDO. However, if the sequencer is paused at
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# just the right time - a parallel fsck(8) on two drives did it for
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# me - then SELINGO can flip back to false before we've seen it. This
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# makes the sequencer sit in the arbitration loop forever. This is
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# Not Good.
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#
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# Therefore, I've added a check in the arbitration loop for SELDO
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# too. This could arguably be made a critical section by disabling
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# pauses, but I don't want to make a potentially infinite loop a CS.
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# I suppose you could fold it into the select loop, too, but since
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# I've been hunting this bug for four days it's kinda like a trophy.
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#
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arbitrate:
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test SSTAT0,0x40 jnz *select # SELDO
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test SSTAT0,0x10 jz arbitrate # SELINGO
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# Wait for a successful selection. If the hardware selection
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# timer goes off, then the driver gets the interrupt, so we don't
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# need to worry about it.
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#
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select:
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test SSTAT0,0x40 jz select # SELDO
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jmp *select
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# Reselection is being initiated by a target - we've seen the BSY
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# line driven active, and we didn't do it! Enable the reselection
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# hardware, and wait for it to finish. Make a note that we've been
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# Reselection has been initiated by a target. Make a note that we've been
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# reselected, but haven't seen an IDENTIFY message from the target
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# yet.
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#
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reselect:
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mvi SCSISEQ,0x10 # ENRSELI
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reselect1:
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test SSTAT0,0x20 jz reselect1 # SELDI
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mov SELID call initialize
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mov SELID call initialize_scsiid
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and FLAGS,0x3f # reselected, no IDENTIFY
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or FLAGS,RESELECTED
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or FLAGS,RESELECTED jmp select2
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# After the [re]selection, make sure that the [re]selection enable
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# bit is off. This chip is flaky enough without extra things
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# turned on. Also clear the BUSFREE bit in SSTAT1 since we'll be
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# using it shortly.
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# After the selection, remove this SCB from the "waiting for selection"
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# list. This is achieved by simply moving our "next" pointer into
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# WAITING_SCBH and setting our next pointer to null so that the next
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# time this SCB is used, we don't get confused.
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#
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*select:
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clr SCSISEQ
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select:
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or SCBARRAY+0,NEEDDMA
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mov WAITING_SCBH,SCBARRAY+30
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mvi SCBARRAY+30,SCB_LIST_NULL
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select2:
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call initialize_for_target
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mvi SCSISEQ,ENRSELI
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mvi CLRSINT0,0x60 # CLRSELDI|CLRSELDO
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mvi CLRSINT1,0x8 # CLRBUSFREE
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# Main loop for information transfer phases. If BSY is false, then
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@ -636,11 +646,12 @@ p_mesgin:
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# Check status for non zero return and interrupt driver if needed
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# This allows the driver to interpret errors only when they occur
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# instead of always uploading the scb. If the status is SCSI_CHECK,
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# the driver will download a new scb requesting sense, to replace
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# the old one and set the SENSE sequencer flag. If the sense flag is
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# set, the sequencer imediately jumps to start working on the sense
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# command. If the kernel driver does not wish to request sense, it need
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# do nothing, and the command is allowed to complete. We don't
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# the driver will download a new scb requesting sense to replace
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# the old one, modify the "waiting for selection" SCB list and set
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# RETURN_1 to 0x80. If RETURN_1 is set to 0x80 the sequencer imediately
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# jumps to main loop where it will run down the waiting SCB list.
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# If the kernel driver does not wish to request sense, it need
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# only clear RETURN_1, and the command is allowed to complete. We don't
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# bother to post to the QOUTFIFO in the error case since it would require
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# extra work in the kernel driver to ensure that the entry was removed
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# before the command complete code tried processing it.
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@ -653,7 +664,7 @@ p_mesgin:
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check_status:
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test SCBARRAY+14,0xff jz status_ok # 0 Status?
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mvi INTSTAT,BAD_STATUS # let driver know
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test FLAGS,SENSE jz status_ok
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test RETURN_1, 0x80 jz status_ok
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jmp p_mesgin_done
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status_ok:
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@ -977,23 +988,21 @@ dma_finish2:
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# the target SCSI ID to be in the upper four bits of SINDEX, and A's
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# contents are stomped on return.
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#
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initialize:
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initialize_scsiid:
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and SINDEX,0xf0 # Get target ID
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and A,0x0f,SCSIID
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or SINDEX,A
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mov SCSIID,SINDEX
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# Esundry initialization.
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#
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clr DROPATN
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clr SIGSTATE
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mov SCSIID,SINDEX ret
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initialize_for_target:
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# Turn on Automatic PIO mode now, before we expect to see a REQ
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# from the target. It shouldn't hurt anything to leave it on. Set
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# CLRCHN here before the target has entered a data transfer mode -
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# with synchronous SCSI, if you do it later, you blow away some
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# data in the SCSI FIFO that the target has already sent to you.
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#
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clr SIGSTATE
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mvi SXFRCTL0,0x8a # DFON|SPIOEN|CLRCHN
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# Initialize scatter-gather pointers by setting up the working copy
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Block a user