[SCSI]: Add help text for SCSI_ESP_CORE.

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/scsi/Kconfig

@@ -1757,6 +1757,14 @@ config SCSI_ESP_CORE
 	tristate "ESP Scsi Driver Core"
 	depends on SCSI
 	select SCSI_SPI_ATTRS
+	help
+	  This is a core driver for NCR53c9x based scsi chipsets,
+	  also known as "ESP" for Emulex Scsi Processor or
+	  Enhanced Scsi Processor.  This driver does not exist by
+	  itself, there are front-end drivers which, when enabled,
+	  select and enable this driver.  One example is SCSI_SUNESP.
+	  These front-end drivers provide probing, DMA, and register
+	  access support for the core driver.
 
 config SCSI_SUNESP
 	tristate "Sparc ESP Scsi Driver"