libata: Media rotation rate and form factor heuristics

This patch provides new heuristics for parsing both the form factor and
media rotation rate ATA IDENFITY words.

The reported ATA version must be 7 or greater and the device must return
values defined as valid in the standard.  Only then are the
characteristics reported to SCSI via the VPD B1 page.

This seems like a reasonable compromise to me considering that we have
been shipping several kernel releases that key off the rotation rate bit
without any version checking whatsoever.  With no complaints so far.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index d1718a1f278aa8b5b46b5bfff06f181db951df7f..342316064e9ffe88b8962910908c345593c9ef1a 100644 (file)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2142,13 +2142,14 @@ static unsigned int ata_scsiop_inq_89(struct ata_scsi_args *args, u8 *rbuf)
 
 static unsigned int ata_scsiop_inq_b1(struct ata_scsi_args *args, u8 *rbuf)
 {
+       int form_factor = ata_id_form_factor(args->id);
+       int media_rotation_rate = ata_id_rotation_rate(args->id);
+
        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] = media_rotation_rate >> 8;
+       rbuf[5] = media_rotation_rate;
+       rbuf[7] = form_factor;
 
        return 0;
 }

diff --git a/include/linux/ata.h b/include/linux/ata.h
index cb79b7a208e17e4ad66acb6fc7231fc10c8acfc1..915da43edee1833acad8c3c2493fc18d8b5cffd2 100644 (file)
--- a/include/linux/ata.h
+++ b/include/linux/ata.h
@@ -730,6 +730,34 @@ static inline int ata_id_has_unload(const u16 *id)
        return 0;
 }
 
+static inline int ata_id_form_factor(const u16 *id)
+{
+       u16 val = id[168];
+
+       if (ata_id_major_version(id) < 7 || val == 0 || val == 0xffff)
+               return 0;
+
+       val &= 0xf;
+
+       if (val > 5)
+               return 0;
+
+       return val;
+}
+
+static inline int ata_id_rotation_rate(const u16 *id)
+{
+       u16 val = id[217];
+
+       if (ata_id_major_version(id) < 7 || val == 0 || val == 0xffff)
+               return 0;
+
+       if (val > 1 && val < 0x401)
+               return 0;
+
+       return val;
+}
+
 static inline int ata_id_has_trim(const u16 *id)
 {
        if (ata_id_major_version(id) >= 7 &&