[PATCH] shpchp: fix improper wait for command completion

Current SHPCHP driver uses msleep_interruptible() function to wait for
a command completion event. But I think this would cause an unnecessary
long wait until timeout, if command completion interrupt came before
task state was changed to TASK_INTERRUPTIBLE. This patch fixes this
issue. With this patch, command completion becomes faster as follows:

o Without this patch

	# time echo 1 > power

	real    0m4.708s
	user    0m0.000s
	sys     0m0.524s

o With this patch

	# time echo 1 > power

	real    0m2.221s
	user    0m0.000s
	sys     0m0.532s

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/pci/hotplug/shpchp.h

@@ -101,6 +101,7 @@ struct controller {
 	u32 cap_offset;
 	unsigned long mmio_base;
 	unsigned long mmio_size;
+	volatile int cmd_busy;
 };
 
 struct hotplug_params {

drivers/pci/hotplug/shpchp_ctrl.c

@@ -248,7 +248,6 @@ static int change_bus_speed(struct controller *ctrl, struct slot *p_slot,
 		up(&ctrl->crit_sect);
 		return WRONG_BUS_FREQUENCY;
 	}
-	wait_for_ctrl_irq (ctrl);
 		
 	if ((rc = p_slot->hpc_ops->check_cmd_status(ctrl))) {
 		err("%s: Can't set bus speed/mode in the case of adapter & bus mismatch\n",
@@ -330,9 +329,6 @@ static int board_added(struct slot *p_slot)
 		up(&ctrl->crit_sect);
 		return -1;
 	}
-			
-	/* Wait for the command to complete */
-	wait_for_ctrl_irq (ctrl);
 	
 	rc = p_slot->hpc_ops->check_cmd_status(ctrl);
 	if (rc) {
@@ -352,7 +348,6 @@ static int board_added(struct slot *p_slot)
 			up(&ctrl->crit_sect);
 			return WRONG_BUS_FREQUENCY;
 		}
-		wait_for_ctrl_irq (ctrl);
 		
 		if ((rc = p_slot->hpc_ops->check_cmd_status(ctrl))) {
 			err("%s: Can't set bus speed/mode in the case of adapter & bus mismatch\n",
@@ -367,7 +362,6 @@ static int board_added(struct slot *p_slot)
 			up(&ctrl->crit_sect);
 			return rc;
 		}
-		wait_for_ctrl_irq (ctrl);
 
 		if ((rc = p_slot->hpc_ops->check_cmd_status(ctrl))) {
 			err("%s: Failed to enable slot, error code(%d)\n", __FUNCTION__, rc);
@@ -494,7 +488,6 @@ static int board_added(struct slot *p_slot)
 		up(&ctrl->crit_sect);
 		return rc;
 	}
-	wait_for_ctrl_irq (ctrl);
 
 	if ((rc = p_slot->hpc_ops->check_cmd_status(ctrl))) {
 		err("%s: Failed to enable slot, error code(%d)\n", __FUNCTION__, rc);
@@ -532,9 +525,6 @@ static int board_added(struct slot *p_slot)
 
 	p_slot->hpc_ops->green_led_on(p_slot);
 
-	/* Wait for the command to complete */
-	wait_for_ctrl_irq (ctrl);
-
 	/* Done with exclusive hardware access */
 	up(&ctrl->crit_sect);
 
@@ -552,8 +542,6 @@ err_exit:
 		up(&ctrl->crit_sect);
 		return rc;
 	}
-	/* Wait for the command to complete */
-	wait_for_ctrl_irq (ctrl);
 
 	rc = p_slot->hpc_ops->check_cmd_status(ctrl);
 	if (rc) {
@@ -603,8 +591,6 @@ static int remove_board(struct slot *p_slot)
 		up(&ctrl->crit_sect);
 		return rc;
 	}
-	/* Wait for the command to complete */
-	wait_for_ctrl_irq (ctrl);
 
 	rc = p_slot->hpc_ops->check_cmd_status(ctrl);
 	if (rc) {
@@ -621,8 +607,6 @@ static int remove_board(struct slot *p_slot)
 		up(&ctrl->crit_sect);
 		return rc;
 	}
-	/* Wait for the command to complete */
-	wait_for_ctrl_irq (ctrl);
 
 	/* Done with exclusive hardware access */
 	up(&ctrl->crit_sect);
@@ -676,9 +660,6 @@ static void shpchp_pushbutton_thread (unsigned long slot)
 
 			p_slot->hpc_ops->green_led_off(p_slot);
 
-			/* Wait for the command to complete */
-			wait_for_ctrl_irq (p_slot->ctrl);
-
 			/* Done with exclusive hardware access */
 			up(&p_slot->ctrl->crit_sect);
 		}
@@ -790,14 +771,9 @@ static void interrupt_event_handler(struct controller *ctrl)
 						down(&ctrl->crit_sect);
 
 						p_slot->hpc_ops->green_led_on(p_slot);
-						/* Wait for the command to complete */
-						wait_for_ctrl_irq (ctrl);
 
 						p_slot->hpc_ops->set_attention_status(p_slot, 0);
 
-						/* Wait for the command to complete */
-						wait_for_ctrl_irq (ctrl);
-
 						/* Done with exclusive hardware access */
 						up(&ctrl->crit_sect);
 						break;
@@ -806,12 +782,8 @@ static void interrupt_event_handler(struct controller *ctrl)
 						down(&ctrl->crit_sect);
 
 						p_slot->hpc_ops->green_led_off(p_slot);
-						/* Wait for the command to complete */
-						wait_for_ctrl_irq (ctrl);
 
 						p_slot->hpc_ops->set_attention_status(p_slot, 0);
-						/* Wait for the command to complete */
-						wait_for_ctrl_irq (ctrl);
 
 						/* Done with exclusive hardware access */
 						up(&ctrl->crit_sect);
@@ -845,14 +817,9 @@ static void interrupt_event_handler(struct controller *ctrl)
 
 					/* blink green LED and turn off amber */
 					p_slot->hpc_ops->green_led_blink(p_slot);
-					/* Wait for the command to complete */
-					wait_for_ctrl_irq (ctrl);
 					
 					p_slot->hpc_ops->set_attention_status(p_slot, 0);
 
-					/* Wait for the command to complete */
-					wait_for_ctrl_irq (ctrl);
-
 					/* Done with exclusive hardware access */
 					up(&ctrl->crit_sect);
 
@@ -870,12 +837,8 @@ static void interrupt_event_handler(struct controller *ctrl)
 					down(&ctrl->crit_sect);
 
 					p_slot->hpc_ops->set_attention_status(p_slot, 1);
-					/* Wait for the command to complete */
-					wait_for_ctrl_irq (ctrl);
 					
 					p_slot->hpc_ops->green_led_off(p_slot);
-					/* Wait for the command to complete */
-					wait_for_ctrl_irq (ctrl);
 
 					/* Done with exclusive hardware access */
 					up(&ctrl->crit_sect);

drivers/pci/hotplug/shpchp_hpc.c

@@ -275,6 +275,25 @@ static void start_int_poll_timer(struct php_ctlr_state_s *php_ctlr, int seconds)
 	return;
 }
 
+static inline int shpc_wait_cmd(struct controller *ctrl)
+{
+	int retval = 0;
+	unsigned int timeout_msec = shpchp_poll_mode ? 2000 : 1000;
+	unsigned long timeout = msecs_to_jiffies(timeout_msec);
+	int rc = wait_event_interruptible_timeout(ctrl->queue,
+						  !ctrl->cmd_busy, timeout);
+	if (!rc) {
+		retval = -EIO;
+		err("Command not completed in %d msec\n", timeout_msec);
+	} else if (rc < 0) {
+		retval = -EINTR;
+		info("Command was interrupted by a signal\n");
+	}
+	ctrl->cmd_busy = 0;
+
+	return retval;
+}
+
 static int shpc_write_cmd(struct slot *slot, u8 t_slot, u8 cmd)
 {
 	struct php_ctlr_state_s *php_ctlr = slot->ctrl->hpc_ctlr_handle;
@@ -314,8 +333,14 @@ static int shpc_write_cmd(struct slot *slot, u8 t_slot, u8 cmd)
 	/* To make sure the Controller Busy bit is 0 before we send out the
 	 * command. 
 	 */
+	slot->ctrl->cmd_busy = 1;
 	writew(temp_word, php_ctlr->creg + CMD);
 
+	/*
+	 * Wait for command completion.
+	 */
+	retval = shpc_wait_cmd(slot->ctrl);
+
 	DBG_LEAVE_ROUTINE 
 	return retval;
 }
@@ -1064,6 +1089,7 @@ static irqreturn_t shpc_isr(int IRQ, void *dev_id, struct pt_regs *regs)
 		temp_dword = readl(php_ctlr->creg + SERR_INTR_ENABLE);
 		temp_dword &= 0xfffdffff;
 		writel(temp_dword, php_ctlr->creg + SERR_INTR_ENABLE);
+		ctrl->cmd_busy = 0;
 		wake_up_interruptible(&ctrl->queue);
 	}