1 files changed, 35 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 7278295f94d2..9a5b6658c65e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -950,6 +950,41 @@ and is between 256 and 4096 characters. It is defined in the file
                         when set.
                         Format: <int>
 
+        libata.force=   [LIBATA] Force configurations.  The format is comma
+                        separated list of "[ID:]VAL" where ID is
+                        PORT[:DEVICE].  PORT and DEVICE are decimal numbers
+                        matching port, link or device.  Basically, it matches
+                        the ATA ID string printed on console by libata.  If
+                        the whole ID part is omitted, the last PORT and DEVICE
+                        values are used.  If ID hasn't been specified yet, the
+                        configuration applies to all ports, links and devices.
+
+                        If only DEVICE is omitted, the parameter applies to
+                        the port and all links and devices behind it.  DEVICE
+                        number of 0 either selects the first device or the
+                        first fan-out link behind PMP device.  It does not
+                        select the host link.  DEVICE number of 15 selects the
+                        host link and device attached to it.
+
+                        The VAL specifies the configuration to force.  As long
+                        as there's no ambiguity shortcut notation is allowed.
+                        For example, both 1.5 and 1.5G would work for 1.5Gbps.
+                        The following configurations can be forced.
+
+                        * Cable type: 40c, 80c, short40c, unk, ign or sata.
+                          Any ID with matching PORT is used.
+
+                        * SATA link speed limit: 1.5Gbps or 3.0Gbps.
+
+                        * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
+                          udma[/][16,25,33,44,66,100,133] notation is also
+                          allowed.
+
+                        * [no]ncq: Turn on or off NCQ.
+
+                        If there are multiple matching configurations changing
+                        the same attribute, the last one is used.
+
         load_ramdisk=   [RAM] List of ramdisks to load from floppy
                         See Documentation/ramdisk.txt.