svn commit: r276407 - head/sys/dev/usb/controller

[Hans Petter Selasky]

Author: hselasky
Date: Tue Dec 30 09:20:29 2014
New Revision: 276407
URL: https://svnweb.freebsd.org/changeset/base/276407

Log:
  Allow systems having a page size greater than 4K to use fewer
  scatter-gather XHCI TRB entries for its payload data. The XHCI
  controller can handle at least 65536 bytes per scatter-gather list
  entry.
  
  MFC after:	1 week
  Suggested by:	Kohji Okuno <okuno.kohji at jp.panasonic.com>

Modified:
  head/sys/dev/usb/controller/xhci.h

Modified: head/sys/dev/usb/controller/xhci.h
==============================================================================
--- head/sys/dev/usb/controller/xhci.h	Tue Dec 30 08:50:50 2014	(r276406)
+++ head/sys/dev/usb/controller/xhci.h	Tue Dec 30 09:20:29 2014	(r276407)
@@ -320,11 +320,23 @@ struct xhci_dev_endpoint_trbs {
 	    XHCI_MAX_TRANSFERS) + XHCI_MAX_STREAMS];
 };
 
-#define	XHCI_TD_PAGE_NBUF	17	/* units, room enough for 64Kbytes */
-#define	XHCI_TD_PAGE_SIZE	4096	/* bytes */
-#define	XHCI_TD_PAYLOAD_MAX	(XHCI_TD_PAGE_SIZE * (XHCI_TD_PAGE_NBUF - 1))
+#if (USB_PAGE_SIZE < 4096)
+#error "The XHCI driver needs a pagesize above 4K"
+#endif
+
+/* Define the maximum payload which we will handle in a single TRB */
+#define	XHCI_TD_PAYLOAD_MAX	65536	/* bytes */
+
+/* Define the maximum payload of a single scatter-gather list element */
+#define	XHCI_TD_PAGE_SIZE \
+  ((USB_PAGE_SIZE < XHCI_TD_PAYLOAD_MAX) ? USB_PAGE_SIZE : XHCI_TD_PAYLOAD_MAX)
+
+/* Define the maximum length of the scatter-gather list */
+#define	XHCI_TD_PAGE_NBUF \
+  (((XHCI_TD_PAYLOAD_MAX + XHCI_TD_PAGE_SIZE - 1) / XHCI_TD_PAGE_SIZE) + 1)
 
 struct xhci_td {
+	/* one LINK TRB has been added to the TRB array */
 	struct xhci_trb		td_trb[XHCI_TD_PAGE_NBUF + 1];
 
 /*