libata: Clear tf before doing request sense (take 3)

patch 2/4:
  Clear tf before doing request sense.

This fixes the AOpen 56X/AKH timeout problem.
(http://bugzilla.kernel.org/show_bug.cgi?id=8244)

Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index c89664a77a9c44c0367dc6cb22e9d16feaa5974d..39f556c0299265ffb99a4430588f7aa9cac194ff 100644 (file)
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -982,26 +982,27 @@ static int ata_eh_read_log_10h(struct ata_device *dev,
  *     RETURNS:
  *     0 on success, AC_ERR_* mask on failure
  */
-static unsigned int atapi_eh_request_sense(struct ata_device *dev,
-                                          unsigned char *sense_buf)
+static unsigned int atapi_eh_request_sense(struct ata_queued_cmd *qc)
 {
+       struct ata_device *dev = qc->dev;
+       unsigned char *sense_buf = qc->scsicmd->sense_buffer;
        struct ata_port *ap = dev->ap;
        struct ata_taskfile tf;
        u8 cdb[ATAPI_CDB_LEN];
 
        DPRINTK("ATAPI request sense\n");
 
-       ata_tf_init(dev, &tf);
-
        /* FIXME: is this needed? */
        memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);
 
-       /* XXX: why tf_read here? */
-       ap->ops->tf_read(ap, &tf);
-
-       /* fill these in, for the case where they are -not- overwritten */
+       /* initialize sense_buf with the error register,
+        * for the case where they are -not- overwritten
+        */
        sense_buf[0] = 0x70;
-       sense_buf[2] = tf.feature >> 4;
+       sense_buf[2] = qc->result_tf.feature >> 4;
+
+       /* some devices time out if garbage left in tf */ 
+       ata_tf_init(dev, &tf);
 
        memset(cdb, 0, ATAPI_CDB_LEN);
        cdb[0] = REQUEST_SENSE;
@@ -1165,8 +1166,7 @@ static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
 
        case ATA_DEV_ATAPI:
                if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {
-                       tmp = atapi_eh_request_sense(qc->dev,
-                                                    qc->scsicmd->sense_buffer);
+                       tmp = atapi_eh_request_sense(qc);
                        if (!tmp) {
                                /* ATA_QCFLAG_SENSE_VALID is used to
                                 * tell atapi_qc_complete() that sense