libata-pmp-prep: implement ATA_LFLAG_DISABLED

Implement ATA_LFLAG_DISABLED.  The flag indicates the link is disabled
due to EH recovery failure.  While a link is disabled, no EH action is
taken on the link and suspend/resume become noop too.

This will be used by PMP links to manage failed links.

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

2 files changed, 32 insertions, 1 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 8f8ed4dfb171..fbbf79163900 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1308,6 +1308,7 @@ static void ata_eh_analyze_serror(struct ata_link *link)
         struct ata_eh_context *ehc = &link->eh_context;
         u32 serror = ehc->i.serror;
         unsigned int err_mask = 0, action = 0;
+        u32 hotplug_mask;
 
         if (serror & SERR_PERSISTENT) {
                 err_mask |= AC_ERR_ATA_BUS;
@@ -1326,7 +1327,20 @@ static void ata_eh_analyze_serror(struct ata_link *link)
                 err_mask |= AC_ERR_SYSTEM;
                 action |= ATA_EH_HARDRESET;
         }
-        if (serror & (SERR_PHYRDY_CHG | SERR_DEV_XCHG))
+
+        /* Determine whether a hotplug event has occurred.  Both
+         * SError.N/X are considered hotplug events for enabled or
+         * host links.  For disabled PMP links, only N bit is
+         * considered as X bit is left at 1 for link plugging.
+         */
+        hotplug_mask = 0;
+
+        if (!(link->flags & ATA_LFLAG_DISABLED) || ata_is_host_link(link))
+                hotplug_mask = SERR_PHYRDY_CHG | SERR_DEV_XCHG;
+        else
+                hotplug_mask = SERR_PHYRDY_CHG;
+
+        if (serror & hotplug_mask)
                 ata_ehi_hotplugged(&ehc->i);
 
         ehc->i.err_mask |= err_mask;
@@ -2227,6 +2241,10 @@ static int ata_eh_skip_recovery(struct ata_link *link)
         struct ata_eh_context *ehc = &link->eh_context;
         struct ata_device *dev;
 
+        /* skip disabled links */
+        if (link->flags & ATA_LFLAG_DISABLED)
+                return 1;
+
         /* thaw frozen port, resume link and recover failed devices */
         if ((link->ap->pflags & ATA_PFLAG_FROZEN) ||
             (ehc->i.flags & ATA_EHI_RESUME_LINK) || ata_link_nr_enabled(link))
@@ -2327,6 +2345,7 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
         struct ata_device *dev;
         int nr_failed_devs, nr_disabled_devs;
         int reset, rc;
+        unsigned long flags;
 
         DPRINTK("ENTER\n");
 
@@ -2334,6 +2353,15 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
         ata_port_for_each_link(link, ap) {
                 struct ata_eh_context *ehc = &link->eh_context;
 
+                /* re-enable link? */
+                if (ehc->i.action & ATA_EH_ENABLE_LINK) {
+                        ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
+                        spin_lock_irqsave(ap->lock, flags);
+                        link->flags &= ~ATA_LFLAG_DISABLED;
+                        spin_unlock_irqrestore(ap->lock, flags);
+                        ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
+                }
+
                 ata_link_for_each_dev(dev, link) {
                         if (link->flags & ATA_LFLAG_NO_RETRY)
                                 ehc->tries[dev->devno] = 1;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index adeee7397cdb..2bd1d26c9c8d 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -170,6 +170,7 @@ enum {
         ATA_LFLAG_ASSUME_SEMB   = (1 << 4), /* assume SEMB class */
         ATA_LFLAG_ASSUME_CLASS  = ATA_LFLAG_ASSUME_ATA | ATA_LFLAG_ASSUME_SEMB,
         ATA_LFLAG_NO_RETRY      = (1 << 5), /* don't retry this link */
+        ATA_LFLAG_DISABLED      = (1 << 6), /* link is disabled */
 
         /* struct ata_port flags */
         ATA_FLAG_SLAVE_POSS     = (1 << 0), /* host supports slave dev */
@@ -289,6 +290,7 @@ enum {
         ATA_EH_REVALIDATE       = (1 << 0),
         ATA_EH_SOFTRESET        = (1 << 1),
         ATA_EH_HARDRESET        = (1 << 2),
+        ATA_EH_ENABLE_LINK      = (1 << 3),
 
         ATA_EH_RESET_MASK       = ATA_EH_SOFTRESET | ATA_EH_HARDRESET,
         ATA_EH_PERDEV_MASK      = ATA_EH_REVALIDATE,
@@ -999,6 +1001,7 @@ static inline void ata_ehi_hotplugged(struct ata_eh_info *ehi)
 {
         ata_ehi_schedule_probe(ehi);
         ehi->flags |= ATA_EHI_HOTPLUGGED;
+        ehi->action |= ATA_EH_ENABLE_LINK;
         ehi->err_mask |= AC_ERR_ATA_BUS;
 }