[SCSI] aic79xx bus reset update

As James B. correctly noted, ahd_reset_channel() in
ahd_linux_bus_reset() should be protected by ahd_lock().  However, the
main reason for not doing so was a deadlock with the interesting
polling mechanism to detect the end a bus reset.

This patch replaces the polling mechanism with a saner signalling via
flags; it also gives us the benefit of detecting any multiple calls to
ahd_reset_channel().

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

3 files changed, 58 insertions, 62 deletions

diff --git a/drivers/scsi/aic7xxx/aic79xx.h b/drivers/scsi/aic7xxx/aic79xx.h
index 1d11f7e77564..933e5101edf6 100644
--- a/drivers/scsi/aic7xxx/aic79xx.h
+++ b/drivers/scsi/aic7xxx/aic79xx.h
@@ -372,7 +372,7 @@ typedef enum {
         AHD_CURRENT_SENSING   = 0x40000,
         AHD_SCB_CONFIG_USED   = 0x80000,/* No SEEPROM but SCB had info. */
         AHD_HP_BOARD          = 0x100000,
-        AHD_RESET_POLL_ACTIVE = 0x200000,
+        AHD_BUS_RESET_ACTIVE  = 0x200000,
         AHD_UPDATE_PEND_CMDS  = 0x400000,
         AHD_RUNNING_QOUTFIFO  = 0x800000,
         AHD_HAD_FIRST_SEL     = 0x1000000
diff --git a/drivers/scsi/aic7xxx/aic79xx_core.c b/drivers/scsi/aic7xxx/aic79xx_core.c
index 326a62226235..880a10def1aa 100644
--- a/drivers/scsi/aic7xxx/aic79xx_core.c
+++ b/drivers/scsi/aic7xxx/aic79xx_core.c
@@ -207,7 +207,6 @@ static void		ahd_add_scb_to_free_list(struct ahd_softc *ahd,
 static u_int            ahd_rem_wscb(struct ahd_softc *ahd, u_int scbid,
                                      u_int prev, u_int next, u_int tid);
 static void             ahd_reset_current_bus(struct ahd_softc *ahd);
-static ahd_callback_t   ahd_reset_poll;
 static ahd_callback_t   ahd_stat_timer;
 #ifdef AHD_DUMP_SEQ
 static void             ahd_dumpseq(struct ahd_softc *ahd);
@@ -1534,6 +1533,18 @@ ahd_handle_scsiint(struct ahd_softc *ahd, u_int intstat)
         lqistat1 = ahd_inb(ahd, LQISTAT1);
         lqostat0 = ahd_inb(ahd, LQOSTAT0);
         busfreetime = ahd_inb(ahd, SSTAT2) & BUSFREETIME;
+
+        /*
+         * Ignore external resets after a bus reset.
+         */
+        if (((status & SCSIRSTI) != 0) && (ahd->flags & AHD_BUS_RESET_ACTIVE))
+                return;
+
+        /*
+         * Clear bus reset flag
+         */
+        ahd->flags &= ~AHD_BUS_RESET_ACTIVE;
+
         if ((status0 & (SELDI|SELDO)) != 0) {
                 u_int simode0;
 
@@ -7847,6 +7858,17 @@ ahd_reset_channel(struct ahd_softc *ahd, char channel, int initiate_reset)
         int     found;
         u_int   fifo;
         u_int   next_fifo;
+        uint8_t scsiseq;
+
+        /*
+         * Check if the last bus reset is cleared
+         */
+        if (ahd->flags & AHD_BUS_RESET_ACTIVE) {
+                printf("%s: bus reset still active\n",
+                       ahd_name(ahd));
+                return 0;
+        }
+        ahd->flags |= AHD_BUS_RESET_ACTIVE;
 
         ahd->pending_device = NULL;
 
@@ -7860,6 +7882,12 @@ ahd_reset_channel(struct ahd_softc *ahd, char channel, int initiate_reset)
         /* Make sure the sequencer is in a safe location. */
         ahd_clear_critical_section(ahd);
 
+        /*
+         * Run our command complete fifos to ensure that we perform
+         * completion processing on any commands that 'completed'
+         * before the reset occurred.
+         */
+        ahd_run_qoutfifo(ahd);
 #ifdef AHD_TARGET_MODE
         if ((ahd->flags & AHD_TARGETROLE) != 0) {
                 ahd_run_tqinfifo(ahd, /*paused*/TRUE);
@@ -7924,30 +7952,14 @@ ahd_reset_channel(struct ahd_softc *ahd, char channel, int initiate_reset)
         ahd_clear_fifo(ahd, 1);
 
         /*
-         * Revert to async/narrow transfers until we renegotiate.
+         * Reenable selections
          */
-        max_scsiid = (ahd->features & AHD_WIDE) ? 15 : 7;
-        for (target = 0; target <= max_scsiid; target++) {
-
-                if (ahd->enabled_targets[target] == NULL)
-                        continue;
-                for (initiator = 0; initiator <= max_scsiid; initiator++) {
-                        struct ahd_devinfo devinfo;
-
-                        ahd_compile_devinfo(&devinfo, target, initiator,
-                                            CAM_LUN_WILDCARD,
-                                            'A', ROLE_UNKNOWN);
-                        ahd_set_width(ahd, &devinfo, MSG_EXT_WDTR_BUS_8_BIT,
-                                      AHD_TRANS_CUR, /*paused*/TRUE);
-                        ahd_set_syncrate(ahd, &devinfo, /*period*/0,
-                                         /*offset*/0, /*ppr_options*/0,
-                                         AHD_TRANS_CUR, /*paused*/TRUE);
-                }
-        }
+        ahd_outb(ahd, SIMODE1, ahd_inb(ahd, SIMODE1) | ENSCSIRST);
+        scsiseq = ahd_inb(ahd, SCSISEQ_TEMPLATE);
+        ahd_outb(ahd, SCSISEQ1, scsiseq & (ENSELI|ENRSELI|ENAUTOATNP));
 
-#ifdef AHD_TARGET_MODE
         max_scsiid = (ahd->features & AHD_WIDE) ? 15 : 7;
-
+#ifdef AHD_TARGET_MODE
         /*
          * Send an immediate notify ccb to all target more peripheral
          * drivers affected by this action.
@@ -7975,51 +7987,31 @@ ahd_reset_channel(struct ahd_softc *ahd, char channel, int initiate_reset)
         /* Notify the XPT that a bus reset occurred */
         ahd_send_async(ahd, devinfo.channel, CAM_TARGET_WILDCARD,
                        CAM_LUN_WILDCARD, AC_BUS_RESET, NULL);
-        ahd_restart(ahd);
+
         /*
-         * Freeze the SIMQ until our poller can determine that
-         * the bus reset has really gone away.  We set the initial
-         * timer to 0 to have the check performed as soon as possible
-         * from the timer context.
+         * Revert to async/narrow transfers until we renegotiate.
          */
-        if ((ahd->flags & AHD_RESET_POLL_ACTIVE) == 0) {
-                ahd->flags |= AHD_RESET_POLL_ACTIVE;
-                ahd_freeze_simq(ahd);
-                ahd_timer_reset(&ahd->reset_timer, 0, ahd_reset_poll, ahd);
-        }
-        return (found);
-}
+        for (target = 0; target <= max_scsiid; target++) {
 
+                if (ahd->enabled_targets[target] == NULL)
+                        continue;
+                for (initiator = 0; initiator <= max_scsiid; initiator++) {
+                        struct ahd_devinfo devinfo;
 
-#define AHD_RESET_POLL_US 1000
-static void
-ahd_reset_poll(void *arg)
-{
-        struct  ahd_softc *ahd = arg;
-        u_int   scsiseq1;
-        u_long  s;
-        
-        ahd_lock(ahd, &s);
-        ahd_pause(ahd);
-        ahd_update_modes(ahd);
-        ahd_set_modes(ahd, AHD_MODE_SCSI, AHD_MODE_SCSI);
-        ahd_outb(ahd, CLRSINT1, CLRSCSIRSTI);
-        if ((ahd_inb(ahd, SSTAT1) & SCSIRSTI) != 0) {
-                ahd_timer_reset(&ahd->reset_timer, AHD_RESET_POLL_US,
-                                ahd_reset_poll, ahd);
-                ahd_unpause(ahd);
-                ahd_unlock(ahd, &s);
-                return;
+                        ahd_compile_devinfo(&devinfo, target, initiator,
+                                            CAM_LUN_WILDCARD,
+                                            'A', ROLE_UNKNOWN);
+                        ahd_set_width(ahd, &devinfo, MSG_EXT_WDTR_BUS_8_BIT,
+                                      AHD_TRANS_CUR, /*paused*/TRUE);
+                        ahd_set_syncrate(ahd, &devinfo, /*period*/0,
+                                         /*offset*/0, /*ppr_options*/0,
+                                         AHD_TRANS_CUR, /*paused*/TRUE);
+                }
         }
 
-        /* Reset is now low.  Complete chip reinitialization. */
-        ahd_outb(ahd, SIMODE1, ahd_inb(ahd, SIMODE1) | ENSCSIRST);
-        scsiseq1 = ahd_inb(ahd, SCSISEQ_TEMPLATE);
-        ahd_outb(ahd, SCSISEQ1, scsiseq1 & (ENSELI|ENRSELI|ENAUTOATNP));
-        ahd_unpause(ahd);
-        ahd->flags &= ~AHD_RESET_POLL_ACTIVE;
-        ahd_unlock(ahd, &s);
-        ahd_release_simq(ahd);
+        ahd_restart(ahd);
+
+        return (found);
 }
 
 /**************************** Statistics Processing ***************************/
diff --git a/drivers/scsi/aic7xxx/aic79xx_osm.c b/drivers/scsi/aic7xxx/aic79xx_osm.c
index bcced0a417e6..66e4a47bb9ee 100644
--- a/drivers/scsi/aic7xxx/aic79xx_osm.c
+++ b/drivers/scsi/aic7xxx/aic79xx_osm.c
@@ -782,6 +782,7 @@ ahd_linux_bus_reset(struct scsi_cmnd *cmd)
 {
         struct ahd_softc *ahd;
         int    found;
+        unsigned long flags;
 
         ahd = *(struct ahd_softc **)cmd->device->host->hostdata;
 #ifdef AHD_DEBUG
@@ -789,8 +790,11 @@ ahd_linux_bus_reset(struct scsi_cmnd *cmd)
                 printf("%s: Bus reset called for cmd %p\n",
                        ahd_name(ahd), cmd);
 #endif
+        ahd_lock(ahd, &flags);
+
         found = ahd_reset_channel(ahd, scmd_channel(cmd) + 'A',
                                   /*initiate reset*/TRUE);
+        ahd_unlock(ahd, &flags);
 
         if (bootverbose)
                 printf("%s: SCSI bus reset delivered. "