libata: add ATA_HORKAGE_NOTRIM

commit 71d126fd upstream.

Some devices lose data on TRIM whether queued or not.  This patch adds
a horkage to disable TRIM.

tj: Collapsed unnecessary if() nesting.
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
[bwh: Backported to 3.2:
 - Adjust context
 - Drop change to show_ata_dev_trim()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/ata/libata-scsi.c

@@ -2473,7 +2473,8 @@ static unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf)
 		rbuf[14] = (lowest_aligned >> 8) & 0x3f;
 		rbuf[15] = lowest_aligned;
 
-		if (ata_id_has_trim(args->id)) {
+		if (ata_id_has_trim(args->id) &&
+		    !(dev->horkage & ATA_HORKAGE_NOTRIM)) {
 			rbuf[14] |= 0x80; /* TPE */
 
 			if (ata_id_has_zero_after_trim(args->id))

include/linux/libata.h

@@ -403,6 +403,8 @@ enum {
 	ATA_HORKAGE_MAX_SEC_LBA48 = (1 << 17),	/* Set max sects to 65535 */
 	ATA_HORKAGE_NOLPM	= (1 << 20),	/* don't use LPM */
 	ATA_HORKAGE_WD_BROKEN_LPM = (1 << 21),	/* some WDs have broken LPM */
+	ATA_HORKAGE_NOTRIM	= (1 << 24),	/* don't use TRIM */
+
 
 	 /* DMA mask for user DMA control: User visible values; DO NOT
 	    renumber */