[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>

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

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
 	 */
+	ahd_outb(ahd, SIMODE1, ahd_inb(ahd, SIMODE1) | ENSCSIRST);
+	scsiseq = ahd_inb(ahd, SCSISEQ_TEMPLATE);
+	ahd_outb(ahd, SCSISEQ1, scsiseq & (ENSELI|ENRSELI|ENAUTOATNP));
+
 	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);
-		}
-	}
-
 #ifdef AHD_TARGET_MODE
-	max_scsiid = (ahd->features & AHD_WIDE) ? 15 : 7;
-
 	/*
 	 * Send an immediate notify ccb to all target more peripheral
 	 * drivers affected by this action.
@@ -7975,53 +7987,33 @@ 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
+	 * Revert to async/narrow transfers until we renegotiate.
-	 * 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.
 	 */
-	if ((ahd->flags & AHD_RESET_POLL_ACTIVE) == 0) {
+	for (target = 0; target <= max_scsiid; target++) {
-		ahd->flags |= AHD_RESET_POLL_ACTIVE;
+
-		ahd_freeze_simq(ahd);
+		if (ahd->enabled_targets[target] == NULL)
-		ahd_timer_reset(&ahd->reset_timer, 0, ahd_reset_poll, ahd);
+			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_restart(ahd);
+
 	return (found);
 }
 
-
-#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;
-	}
-
-	/* 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);
-}
-
 /**************************** Statistics Processing ***************************/
 static void
 ahd_stat_timer(void *arg)

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. "