> gp wrote:
> > Jeff
> >
> > I think I may have found an issue in the ATAPI code in the function
> > atapi_packet_task.
> >
> > From my testing with the sata_via driver, I have been getting a timeout
> > when sending the first inquiry command.
> >
> >
> > Here is the section of code of interest:
> >
> >
> > /* make sure DRQ is set */
> > status = ata_chk_status(ap);
> > if ((status & (ATA_BUSY | ATA_DRQ)) != ATA_DRQ)
> > goto err_out;
> >
> > /* send SCSI cdb */
> > DPRINTK("send cdb\n");
> > assert(ap->cdb_len >= 12);
> > ata_data_xfer(ap, qc->cdb, ap->cdb_len, 1);
> >
> > ** Wait is needed here to work correctly
> > DPRINTK("Wait for a bit\n");
> >
> > /* if we are DMA'ing, irq handler takes over from here */
> > if (qc->tf.protocol == ATA_PROT_ATAPI_DMA)
> > ap->ops->bmdma_start(qc); /* initiate bmdma */
> >
> >
> > In the test case, the dma transfer is being used. From my perusal of the
> > ATA spec in section 9.8, it looks like there needs to be a definite
> > state transition before issuing the bmdma_start.
>
> Yeah, it looks like there needs to be an intrq-wait state in there...
>
> Wanna submit a patch? :)
>
I'm a little confused about what is the "correct behavior" of ATAPI DMA INTRQ.
1. The ATA-4 flowchart and ATA-6 state diagram seems to be inconsistent.
In the ATA-4 flowchart, no wait for INTRQ is specified.
2. From the ATA-5 errata:
http://www.t13.org/project/e01122r0.pdf
"...Page 265 through 270 of NCITS 340-2000 clause 9.8 was not properly
converted from the flow
charts in NCITS 317-1998 to the state diagrams. The state diagrams figures 33
and 34 and
associated text is modified to indicate that the device interrupts only at
command completion. "
Notice the "device interrupts only at command completion." statement.
However, the diagrams in the errata are inconsistent with the above statement.
3. The ide-cd code does not wait for INTRQ before starting BM-DMA
/* Arm the interrupt handler. */
ide_set_handler(drive, handler, rq->timeout, cdrom_timer_expiry);
/* ATAPI commands get padded out to 12 bytes minimum */
cmd_len = COMMAND_SIZE(rq->cmd[0]);
if (cmd_len < ATAPI_MIN_CDB_BYTES)
cmd_len = ATAPI_MIN_CDB_BYTES;
/* Send the command to the device. */
HWIF(drive)->atapi_output_bytes(drive, rq->cmd, cmd_len);
/* Start the DMA if need be */
if (info->dma)
hwif->dma_start(drive);
return ide_started;
4. My CD-ROM drive does not generate INTRQ after it received the command packet.
It only assert DMARQ.
Maybe the state diagrams in ATA-5 and ATA-6 are incorrect? Any idea?
Albert
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