Re: [PATCH 45/48] hpsa: shorten the wait for the CISS doorbell mode change ack

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On 01/14/2015 11:03 PM, Don Brace wrote:
> From: Robert Elliott <elliott@xxxxxx>
>
> Shorten the wait for the CISS configuration table doorbell mode
> change acknowledgment from 300-600 s to 20 s, which is the value
> specified in the CISS specification that should be honored by
> all controllers.
>
> Wait using interruptible msleep() rather than uninterruptible
> usleep_range(), which triggers rt_sched timeout errors if the
> wait is long.

The documentation suggest to use for small delays usleep_range :
"msleep(1~20) may not do what the caller intends, and  will often
sleep longer (~20 ms actual sleep for any value given in the 1~20ms
range)." I have also observed issues related to long sleeps in 
hpsa_wait_for_clear_event_notify_ack, but this was related to the use
of system workqueue. (http://www.spinics.net/lists/linux-scsi/msg80035.html)

Tomas

>
> Reviewed-by: Scott Teel <scott.teel@xxxxxxxx>
> Signed-off-by: Robert Elliott <elliott@xxxxxx>
> Signed-off-by: Don Brace <don.brace@xxxxxxxx>
> ---
>  drivers/scsi/hpsa.c |   15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
> index a92653a..89744a1 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -60,8 +60,11 @@
>  #define DRIVER_NAME "HP HPSA Driver (v " HPSA_DRIVER_VERSION ")"
>  #define HPSA "hpsa"
>  
> -/* How long to wait (in milliseconds) for board to go into simple mode */
> -#define MAX_CONFIG_WAIT 30000
> +/* How long to wait for CISS doorbell communication */
> +#define CLEAR_EVENT_WAIT_INTERVAL 20	/* ms for each msleep() call */
> +#define MODE_CHANGE_WAIT_INTERVAL 10	/* ms for each msleep() call */
> +#define MAX_CLEAR_EVENT_WAIT 30000	/* times 20 ms = 600 s */
> +#define MAX_MODE_CHANGE_WAIT 2000	/* times 10 ms = 20 s */
>  #define MAX_IOCTL_CONFIG_WAIT 1000
>  
>  /*define how many times we will try a command because of bus resets */
> @@ -6194,14 +6197,14 @@ static void hpsa_wait_for_clear_event_notify_ack(struct ctlr_info *h)
>  	u32 doorbell_value;
>  	unsigned long flags;
>  	/* wait until the clear_event_notify bit 6 is cleared by controller. */
> -	for (i = 0; i < MAX_CONFIG_WAIT; i++) {
> +	for (i = 0; i < MAX_CLEAR_EVENT_WAIT; i++) {
>  		spin_lock_irqsave(&h->lock, flags);
>  		doorbell_value = readl(h->vaddr + SA5_DOORBELL);
>  		spin_unlock_irqrestore(&h->lock, flags);
>  		if (!(doorbell_value & DOORBELL_CLEAR_EVENTS))
>  			break;
>  		/* delay and try again */
> -		msleep(20);
> +		msleep(CLEAR_EVENT_WAIT_INTERVAL);
>  	}
>  }
>  
> @@ -6215,14 +6218,14 @@ static void hpsa_wait_for_mode_change_ack(struct ctlr_info *h)
>  	 * (e.g.: hot replace a failed 144GB drive in a RAID 5 set right
>  	 * as we enter this code.)
>  	 */
> -	for (i = 0; i < MAX_CONFIG_WAIT; i++) {
> +	for (i = 0; i < MAX_MODE_CHANGE_WAIT; i++) {
>  		spin_lock_irqsave(&h->lock, flags);
>  		doorbell_value = readl(h->vaddr + SA5_DOORBELL);
>  		spin_unlock_irqrestore(&h->lock, flags);
>  		if (!(doorbell_value & CFGTBL_ChangeReq))
>  			break;
>  		/* delay and try again */
> -		usleep_range(10000, 20000);
> +		msleep(MODE_CHANGE_WAIT_INTERVAL);
>  	}
>  }
>  
>
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