USB: xhci: Work around for chain bit in link TRBs.

[~andy/linux] / drivers / usb / host / xhci-hcd.c

diff --git a/drivers/usb/host/xhci-hcd.c b/drivers/usb/host/xhci-hcd.c
index 816c39caca1cf6bf5e1ca9b4a9c8c5d03684fcf3..994f4c0dda24e1cd1a0f022cf71e058487a3f15b 100644 (file)
--- a/drivers/usb/host/xhci-hcd.c
+++ b/drivers/usb/host/xhci-hcd.c
@@ -22,12 +22,18 @@
 
 #include <linux/irq.h>
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 
 #include "xhci.h"
 
 #define DRIVER_AUTHOR "Sarah Sharp"
 #define DRIVER_DESC "'eXtensible' Host Controller (xHC) Driver"
 
+/* Some 0.95 hardware can't handle the chain bit on a Link TRB being cleared */
+static int link_quirk;
+module_param(link_quirk, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(link_quirk, "Don't clear the chain bit on a link TRB");
+
 /* TODO: copied from ehci-hcd.c - can this be refactored? */
 /*
  * handshake - spin reading hc until handshake completes or fails
@@ -214,6 +220,12 @@ int xhci_init(struct usb_hcd *hcd)
 
        xhci_dbg(xhci, "xhci_init\n");
        spin_lock_init(&xhci->lock);
+       if (link_quirk) {
+               xhci_dbg(xhci, "QUIRK: Not clearing Link TRB chain bits.\n");
+               xhci->quirks |= XHCI_LINK_TRB_QUIRK;
+       } else {
+               xhci_dbg(xhci, "xHCI has no QUIRKS\n");
+       }
        retval = xhci_mem_init(xhci, GFP_KERNEL);
        xhci_dbg(xhci, "Finished xhci_init\n");