Re: [PATCH 5 of 8] sd: Detect non-rotational devices

[Matthew Wilcox <matthew@wil.cx>]

On Thu, Apr 23, 2009 at 07:09:37AM -0400, Jeff Garzik wrote:
> Jens Axboe wrote:
> >>+	/* Block Device Characteristics VPD */
> >>+	buffer = scsi_get_vpd_page(sdkp->device, 0xb1);
> >>+
> >>+	if (buffer == NULL)
> >>+		return;
> >>+
> >>+	rot = get_unaligned_be16(&buffer[4]);
>
> >Make sure this works for libata as well, and then kill the rotational
> >check in there instead.
> 
> Yep.  libata-scsi.c would need to simulate that VPD page.

I already did that.  The only problem is that you made me include the stupid:

        if (ata_id_major_version(args->id) > 7) {

so of course it doesn't work on any existing hardware.  How about
applying this patch:

----

libata: fill in b1 page for all drives, not just ATA-8

Some of the drives on the market fill in the rotational speed and form
factor correctly, even though they claim support for an earlier version
of ATA.  The current ata_id_is_ssd() code doesn't check the version
number and doesn't appear to have caused any trouble.  Besides, SCSI devices
are also capable of returning garbage in these fields.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 2733b0c..59358ca 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2144,11 +2144,9 @@ static unsigned int ata_scsiop_inq_b1(struct ata_scsi_args *args, u8 *rbuf)
 {
 	rbuf[1] = 0xb1;
 	rbuf[3] = 0x3c;
-	if (ata_id_major_version(args->id) > 7) {
-		rbuf[4] = args->id[217] >> 8;
-		rbuf[5] = args->id[217];
-		rbuf[7] = args->id[168] & 0xf;
-	}
+	rbuf[4] = args->id[217] >> 8;
+	rbuf[5] = args->id[217];
+	rbuf[7] = args->id[168] & 0xf;
 
 	return 0;
 }

> Also (to mkp or whoever does the work) -- note Linus's comment, and my 
> provisional patch[1], about libata potentially wanting to detect NONROT 
> by looking for "*SSD" from IDENTIFY DEVICE'S model string.

Found it ... and Jens' suggestion that this be done in userspace instead.

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."