libata-pmp-prep: implement ATA_LFLAG_NO_SRST, ASSUME_ATA and ASSUME_SEMB

Some links on some PMPs locks up on SRST and/or report incorrect
device signature.  Implement ATA_LFLAG_NO_SRST, ASSUME_ATA and
ASSUME_SEMB to handle these quirky links.  NO_SRST makes EH avoid
SRST.  ASSUME_ATA and SEMB forces class code to ATA and SEMB_UNSUP
respectively.  Note that SEMB isn't currently supported yet so the
_UNSUP variant is used.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

2 files changed, 36 insertions, 10 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 5244723952c2..7be04bd30bfe 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1906,14 +1906,18 @@ static int ata_do_reset(struct ata_link *link, ata_reset_fn_t reset,
         return 0;
 }
 
-static int ata_eh_followup_srst_needed(int rc, int classify,
+static int ata_eh_followup_srst_needed(struct ata_link *link,
+                                       int rc, int classify,
                                        const unsigned int *classes)
 {
+        if (link->flags & ATA_LFLAG_NO_SRST)
+                return 0;
         if (rc == -EAGAIN)
                 return 1;
         if (rc != 0)
                 return 0;
-        if (classify && classes[0] == ATA_DEV_UNKNOWN)
+        if (classify && !(link->flags & ATA_LFLAG_ASSUME_CLASS) &&
+            classes[0] == ATA_DEV_UNKNOWN)
                 return 1;
         return 0;
 }
@@ -1940,7 +1944,8 @@ int ata_eh_reset(struct ata_link *link, int classify,
          */
         action = ehc->i.action;
         ehc->i.action &= ~ATA_EH_RESET_MASK;
-        if (softreset && (!hardreset || (!sata_set_spd_needed(link) &&
+        if (softreset && (!hardreset || (!(link->flags & ATA_LFLAG_NO_SRST) &&
+                                         !sata_set_spd_needed(link) &&
                                          !(action & ATA_EH_HARDRESET))))
                 ehc->i.action |= ATA_EH_SOFTRESET;
         else
@@ -2003,7 +2008,7 @@ int ata_eh_reset(struct ata_link *link, int classify,
         rc = ata_do_reset(link, reset, classes, deadline);
 
         if (reset == hardreset &&
-            ata_eh_followup_srst_needed(rc, classify, classes)) {
+            ata_eh_followup_srst_needed(link, rc, classify, classes)) {
                 /* okay, let's do follow-up softreset */
                 reset = softreset;
 
@@ -2018,8 +2023,8 @@ int ata_eh_reset(struct ata_link *link, int classify,
                 ata_eh_about_to_do(link, NULL, ATA_EH_RESET_MASK);
                 rc = ata_do_reset(link, reset, classes, deadline);
 
-                if (rc == 0 && classify &&
-                    classes[0] == ATA_DEV_UNKNOWN) {
+                if (rc == 0 && classify && classes[0] == ATA_DEV_UNKNOWN &&
+                    !(link->flags & ATA_LFLAG_ASSUME_CLASS)) {
                         ata_link_printk(link, KERN_ERR,
                                         "classification failed\n");
                         rc = -EINVAL;
@@ -2027,6 +2032,10 @@ int ata_eh_reset(struct ata_link *link, int classify,
                 }
         }
 
+        /* if we skipped follow-up srst, clear rc */
+        if (rc == -EAGAIN)
+                rc = 0;
+
         if (rc && try < ARRAY_SIZE(ata_eh_reset_timeouts)) {
                 unsigned long now = jiffies;
 
@@ -2051,12 +2060,25 @@ int ata_eh_reset(struct ata_link *link, int classify,
         if (rc == 0) {
                 u32 sstatus;
 
-                /* After the reset, the device state is PIO 0 and the
-                 * controller state is undefined.  Record the mode.
-                 */
-                ata_link_for_each_dev(dev, link)
+                ata_link_for_each_dev(dev, link) {
+                        /* After the reset, the device state is PIO 0
+                         * and the controller state is undefined.
+                         * Record the mode.
+                         */
                         dev->pio_mode = XFER_PIO_0;
 
+                        if (ata_link_offline(link))
+                                continue;
+
+                        /* apply class override and convert UNKNOWN to NONE */
+                        if (link->flags & ATA_LFLAG_ASSUME_ATA)
+                                classes[dev->devno] = ATA_DEV_ATA;
+                        else if (link->flags & ATA_LFLAG_ASSUME_SEMB)
+                                classes[dev->devno] = ATA_DEV_SEMB_UNSUP; /* not yet */
+                        else if (classes[dev->devno] == ATA_DEV_UNKNOWN)
+                                classes[dev->devno] = ATA_DEV_NONE;
+                }
+
                 /* record current link speed */
                 if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
                         link->sata_spd = (sstatus >> 4) & 0xf;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index f9f81fd93293..6266fffb0eb3 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -165,6 +165,10 @@ enum {
         ATA_LFLAG_HRST_TO_RESUME = (1 << 0), /* hardreset to resume link */
         ATA_LFLAG_SKIP_D2H_BSY  = (1 << 1), /* can't wait for the first D2H
                                              * Register FIS clearing BSY */
+        ATA_LFLAG_NO_SRST       = (1 << 2), /* avoid softreset */
+        ATA_LFLAG_ASSUME_ATA    = (1 << 3), /* assume ATA class */
+        ATA_LFLAG_ASSUME_SEMB   = (1 << 4), /* assume SEMB class */
+        ATA_LFLAG_ASSUME_CLASS  = ATA_LFLAG_ASSUME_ATA | ATA_LFLAG_ASSUME_SEMB,
 
         /* struct ata_port flags */
         ATA_FLAG_SLAVE_POSS     = (1 << 0), /* host supports slave dev */