Messages in this thread | | | Date | Wed, 14 Nov 2007 12:21:46 -0500 | From | Mark Lord <> | Subject | Re: libata/PATA: GPCMD_SET_STREAMING via SG_IO does nothing |
| |
Sebastian Kemper wrote: > Hi Mark! > > On Wed, Nov 14, 2007 at 11:41:37AM -0500, Mark Lord wrote: >> Ahh.. got it. The host_status returned (not checked by that code) was 7, >> which means "host error". >> >> In this case, that's because the cmd_len is (16), which is too large for >> ATAPI. >> It needs to be changed to (12) instead. > > I don't understand. You seem to use a cmd_len of 16 in hdparm yourself. ..
Really? Where?
> And why does it work with the "old" ATA driver and not with libata if > 16 is too large for ATAPI in general? ..
Now that *is* the question. And the answer appears to be that ide-cd.c ignores the passed-in cmd_len, and replaces it with:
cmd_len = COMMAND_SIZE(rq->cmd[0]);
That's a SCSI macro to calculate the correct cmd_len based on the SCSI opcode, which is very appropriate here. We should do that too (we don't) in libata.
But not exactly as IDE does it -- that's actually a bug: the code needs to also check that the new cmd_len is no larger than the original, or we'll get an Oops.
I'll cook up a patch for that shortly and try it before posting it here.
-ml - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |