libata: use ata_exec_internal() for PMP register access

PMP registers used to be accessed with dedicated accessors ->pmp_read
and ->pmp_write.  During reset, those callbacks are called with the
port frozen so they should be able to run without depending on
interrupt delivery.  To achieve this, they were implemented polling.

However, as resetting the host port makes the PMP to isolate fan-out
ports until SError.X is cleared, resetting fan-out ports while port is
frozen doesn't buy much additional safety.

This patch updates libata PMP support such that PMP registers are
accessed using regular ata_exec_internal() mechanism and kills
->pmp_read/write() callbacks.  The following changes are made.

* PMP access helpers - sata_pmp_read_init_tf(), sata_pmp_read_val(),
  sata_pmp_write_init_tf() are folded into sata_pmp_read/write() which
  are now standalone PMP register access functions.

* sata_pmp_read/write() returns err_mask instead of rc.  This is
  consistent with other functions which issue internal commands and
  allows more detailed error reporting.

* ahci interrupt handler is modified to ignore BAD_PMP and
  spurious/illegal completion IRQs while reset is in progress.  These
  conditions are expected during reset.

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

1 files changed, 14 insertions, 3 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 1f84e40fa6ae..5a2b2af4d0c1 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2557,7 +2557,11 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 
         /* reset */
         if (reset) {
-                ata_eh_freeze_port(ap);
+                /* if PMP is attached, this function only deals with
+                 * downstream links, port should stay thawed.
+                 */
+                if (!ap->nr_pmp_links)
+                        ata_eh_freeze_port(ap);
 
                 ata_port_for_each_link(link, ap) {
                         struct ata_eh_context *ehc = &link->eh_context;
@@ -2575,7 +2579,8 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
                         }
                 }
 
-                ata_eh_thaw_port(ap);
+                if (!ap->nr_pmp_links)
+                        ata_eh_thaw_port(ap);
         }
 
         /* the rest */
@@ -2610,8 +2615,14 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
                 if (ata_eh_handle_dev_fail(dev, rc))
                         nr_disabled_devs++;
 
-                if (ap->pflags & ATA_PFLAG_FROZEN)
+                if (ap->pflags & ATA_PFLAG_FROZEN) {
+                        /* PMP reset requires working host port.
+                         * Can't retry if it's frozen.
+                         */
+                        if (ap->nr_pmp_links)
+                                goto out;
                         break;
+                }
         }
 
         if (nr_failed_devs) {