Changes between Version 14 and Version 15 of USB

Timestamp:

11/05/2019 06:49:42 PM (5 years ago)

Author:

Tim Harvey

Comment:

additional clarification for miniPCIe socket power switch

USB

@@ -303 +303 @@
 Further information regarding these ioctls can be found throughout the ​[http://lxr.free-electrons.com/source/Documentation/ Linux source documentation].
 
-=== Switched Socket Power ===
-
-GW53xx and GW54xx boards with -G and later revisions have a power switch added that can enable and disable power on a single slot by toggling a GPIO.  Power is enabled by default.  
-
-On both GW53xx and GW54xx this is GPIO79 (GPIO bank 3, DIO 15), pad PAD_EIM_DA15__GPIO3_IO15. 
-
-To toggle this GPIO:
-
-{{{#!bash
+=== Switched miniPCIe Socket Power
+On some Gateworks boards the 3.3V power to certain miniPCIe sockets is run through a power switch connected to a GPIO to allow power-cycling devices in the socket. Note that certain miniPCIe form-factor devices may not power-cycle if they backfeed power through PERST# or WLAN_DIS# signals. If power disable capability is provided on a board/socket it is typically on the miniPCIe socket intended for USB based modems (as you can't power cycle devices on the PCI bus without re-enumerating them).
+
+Boards featuring miniPCIe socket power disable:
+||= Board   =||= miniPCIe socket =||= enable =||= gpio =||= Notes =||
+|| GW53xx-G+ || J6 (modem)        || PAD_EIM_DA15_GPIO3_IO15 || gpio79 || active-high enable ||
+|| GW54xx-G+ || J7 (modem)        || PAD_EIM_DA15_GPIO3_IO15 || gpio79 || active-high enable ||
+
+Examples:
+ * Toggle socket power in Linux on a GW53xx-G+ (J6) or GW54xx-G+ (J7):
+{{{#!bash
+# export gpio79 and configure it as an output
 echo 79 > /sys/class/gpio/export 
 echo out > /sys/class/gpio/gpio79/direction
-echo 0 > /sys/class/gpio/gpio79/value # '0' will disable power, '1' will enable power.  
+echo 0 > /sys/class/gpio/gpio79/value # disable power
+echo 1 > /sys/class/gpio/gpio79/value # enable power  
 }}}