[SCSI] lpfc 8.3.40: Clarified the behavior of the lpfc_max_luns module parameter

/*******************************************************************

 * This file is part of the Emulex Linux Device Driver for         *

 * Fibre Channel Host Bus Adapters.                                *

 * Copyright (C) 2004-2012 Emulex.  All rights reserved.           *

 * Copyright (C) 2004-2013 Emulex.  All rights reserved.           *

 * EMULEX and SLI are trademarks of Emulex.                        *

 * www.emulex.com                                                  *

 * Portions Copyright (C) 2004-2005 Christoph Hellwig              *

		 "during discovery");

/*

# lpfc_max_luns: maximum allowed LUN.

# lpfc_max_luns: maximum allowed LUN ID. This is the highest LUN ID that

#    will be scanned by the SCSI midlayer when sequential scanning is

#    used; and is also the highest LUN ID allowed when the SCSI midlayer

#    parses REPORT_LUN responses. The lpfc driver has no LUN count or

#    LUN ID limit, but the SCSI midlayer requires this field for the uses

#    above. The lpfc driver limits the default value to 255 for two reasons.

#    As it bounds the sequential scan loop, scanning for thousands of luns

#    on a target can take minutes of wall clock time.  Additionally,

#    there are FC targets, such as JBODs, that only recognize 8-bits of

#    LUN ID. When they receive a value greater than 8 bits, they chop off

#    the high order bits. In other words, they see LUN IDs 0, 256, 512,

#    and so on all as LUN ID 0. This causes the linux kernel, which sees

#    valid responses at each of the LUN IDs, to believe there are multiple

#    devices present, when in fact, there is only 1.

#    A customer that is aware of their target behaviors, and the results as

#    indicated above, is welcome to increase the lpfc_max_luns value.

#    As mentioned, this value is not used by the lpfc driver, only the

#    SCSI midlayer.

# Value range is [0,65535]. Default value is 255.

# NOTE: The SCSI layer might probe all allowed LUN on some old targets.

*/

LPFC_VPORT_ATTR_R(max_luns, 255, 0, 65535, "Maximum allowed LUN");

LPFC_VPORT_ATTR_R(max_luns, 255, 0, 65535, "Maximum allowed LUN ID");

/*

# lpfc_poll_tmo: .Milliseconds driver will wait between polling FCP ring.