1 files changed, 18 insertions, 5 deletions

diff --git a/drivers/scsi/aic7xxx/aic7xxx_osm.c b/drivers/scsi/aic7xxx/aic7xxx_osm.c
index aa4be8a31415..64c8b88a429f 100644
--- a/drivers/scsi/aic7xxx/aic7xxx_osm.c
+++ b/drivers/scsi/aic7xxx/aic7xxx_osm.c
@@ -341,7 +341,7 @@ MODULE_LICENSE("Dual BSD/GPL");
 MODULE_VERSION(AIC7XXX_DRIVER_VERSION);
 module_param(aic7xxx, charp, 0444);
 MODULE_PARM_DESC(aic7xxx,
-"period delimited, options string.\n"
+"period-delimited options string:\n"
 "       verbose                 Enable verbose/diagnostic logging\n"
 "       allow_memio             Allow device registers to be memory mapped\n"
 "       debug                   Bitmask of debug values to enable\n"
@@ -2539,15 +2539,28 @@ static void ahc_linux_set_iu(struct scsi_target *starget, int iu)
 static void ahc_linux_get_signalling(struct Scsi_Host *shost)
 {
         struct ahc_softc *ahc = *(struct ahc_softc **)shost->hostdata;
-        u8 mode = ahc_inb(ahc, SBLKCTL);
+        unsigned long flags;
+        u8 mode;
 
-        if (mode & ENAB40)
-                spi_signalling(shost) = SPI_SIGNAL_LVD;
-        else if (mode & ENAB20)
+        if (!(ahc->features & AHC_ULTRA2)) {
+                /* non-LVD chipset, may not have SBLKCTL reg */
                 spi_signalling(shost) = 
                         ahc->features & AHC_HVD ?
                         SPI_SIGNAL_HVD :
                         SPI_SIGNAL_SE;
+                return;
+        }
+
+        ahc_lock(ahc, &flags);
+        ahc_pause(ahc);
+        mode = ahc_inb(ahc, SBLKCTL);
+        ahc_unpause(ahc);
+        ahc_unlock(ahc, &flags);
+
+        if (mode & ENAB40)
+                spi_signalling(shost) = SPI_SIGNAL_LVD;
+        else if (mode & ENAB20)
+                spi_signalling(shost) = SPI_SIGNAL_SE;
         else
                 spi_signalling(shost) = SPI_SIGNAL_UNKNOWN;
 }