EHCI: force high-speed devices to run at full speed
This patch (as710) adds a sysfs class-device attribute file named
"companion" for EHCI controllers. The file contains a list of port
numbers that are dedicated to the companion controller; by writing a
port number to the file the user can force a high-speed device
attached directly to the computer to run at full speed. (As far as I
know it is not possible to do this for a device attached to an
external hub.) A port is removed from the file by writing the
negative of its port number.
Several users have asked for this facility and it seems like a useful
thing to have. Every now and then one runs across a device which
behaves much better at full speed than at high speed.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index 076474d..3cfba69 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -190,6 +190,103 @@
/*-------------------------------------------------------------------------*/
+/* Display the ports dedicated to the companion controller */
+static ssize_t show_companion(struct class_device *class_dev, char *buf)
+{
+ struct ehci_hcd *ehci;
+ int nports, index, n;
+ int count = PAGE_SIZE;
+ char *ptr = buf;
+
+ ehci = hcd_to_ehci(bus_to_hcd(class_get_devdata(class_dev)));
+ nports = HCS_N_PORTS(ehci->hcs_params);
+
+ for (index = 0; index < nports; ++index) {
+ if (test_bit(index, &ehci->companion_ports)) {
+ n = scnprintf(ptr, count, "%d\n", index + 1);
+ ptr += n;
+ count -= n;
+ }
+ }
+ return ptr - buf;
+}
+
+/*
+ * Dedicate or undedicate a port to the companion controller.
+ * Syntax is "[-]portnum", where a leading '-' sign means
+ * return control of the port to the EHCI controller.
+ */
+static ssize_t store_companion(struct class_device *class_dev,
+ const char *buf, size_t count)
+{
+ struct ehci_hcd *ehci;
+ int portnum, new_owner, try;
+ u32 __iomem *status_reg;
+ u32 port_status;
+
+ ehci = hcd_to_ehci(bus_to_hcd(class_get_devdata(class_dev)));
+ new_owner = PORT_OWNER; /* Owned by companion */
+ if (sscanf(buf, "%d", &portnum) != 1)
+ return -EINVAL;
+ if (portnum < 0) {
+ portnum = - portnum;
+ new_owner = 0; /* Owned by EHCI */
+ }
+ if (portnum <= 0 || portnum > HCS_N_PORTS(ehci->hcs_params))
+ return -ENOENT;
+ status_reg = &ehci->regs->port_status[--portnum];
+ if (new_owner)
+ set_bit(portnum, &ehci->companion_ports);
+ else
+ clear_bit(portnum, &ehci->companion_ports);
+
+ /*
+ * The controller won't set the OWNER bit if the port is
+ * enabled, so this loop will sometimes require at least two
+ * iterations: one to disable the port and one to set OWNER.
+ */
+
+ for (try = 4; try > 0; --try) {
+ spin_lock_irq(&ehci->lock);
+ port_status = ehci_readl(ehci, status_reg);
+ if ((port_status & PORT_OWNER) == new_owner
+ || (port_status & (PORT_OWNER | PORT_CONNECT))
+ == 0)
+ try = 0;
+ else {
+ port_status ^= PORT_OWNER;
+ port_status &= ~(PORT_PE | PORT_RWC_BITS);
+ ehci_writel(ehci, port_status, status_reg);
+ }
+ spin_unlock_irq(&ehci->lock);
+ if (try > 1)
+ msleep(5);
+ }
+ return count;
+}
+static CLASS_DEVICE_ATTR(companion, 0644, show_companion, store_companion);
+
+static inline void create_companion_file(struct ehci_hcd *ehci)
+{
+ int i;
+
+ /* with integrated TT there is no companion! */
+ if (!ehci_is_TDI(ehci))
+ i = class_device_create_file(ehci_to_hcd(ehci)->self.class_dev,
+ &class_device_attr_companion);
+}
+
+static inline void remove_companion_file(struct ehci_hcd *ehci)
+{
+ /* with integrated TT there is no companion! */
+ if (!ehci_is_TDI(ehci))
+ class_device_remove_file(ehci_to_hcd(ehci)->self.class_dev,
+ &class_device_attr_companion);
+}
+
+
+/*-------------------------------------------------------------------------*/
+
static int check_reset_complete (
struct ehci_hcd *ehci,
int index,
@@ -504,6 +601,16 @@
ehci_readl(ehci, status_reg));
}
+ /* transfer dedicated ports to the companion hc */
+ if ((temp & PORT_CONNECT) &&
+ test_bit(wIndex, &ehci->companion_ports)) {
+ temp &= ~PORT_RWC_BITS;
+ temp |= PORT_OWNER;
+ ehci_writel(ehci, temp, status_reg);
+ ehci_dbg(ehci, "port %d --> companion\n", wIndex + 1);
+ temp = ehci_readl(ehci, status_reg);
+ }
+
/*
* Even if OWNER is set, there's no harm letting khubd
* see the wPortStatus values (they should all be 0 except
