USB: ehci-pci: USB host controller support for Intel Quark X1000

The EHCI packet buffer in/out threshold is programmable for Intel Quark X1000
USB host controller, and the default value is 0x20 dwords. The in/out threshold
can be programmed to 0x80 dwords (512 Bytes) to maximize the perfomrance,
but only when isochronous/interrupt transactions are not initiated by the USB
host controller. This patch is to reconfigure the packet buffer in/out
threshold as maximal as possible to maximize the performance, and 0x7F dwords
(508 Bytes) should be used because the USB host controller initiates
isochronous/interrupt transactions.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@intel.com>
Signed-off-by: Alvin (Weike) Chen <alvin.chen@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c
index 3e86bf4371b3901de76ed7e5db8e8a8de5a72cd3..ca7b964124af1fcdedc72bb46b9f17ae719eaf83 100644 (file)
--- a/drivers/usb/host/ehci-pci.c
+++ b/drivers/usb/host/ehci-pci.c
@@ -35,6 +35,21 @@ static const char hcd_name[] = "ehci-pci";
 #define PCI_DEVICE_ID_INTEL_CE4100_USB 0x2e70
 
 /*-------------------------------------------------------------------------*/
+#define PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC            0x0939
+static inline bool is_intel_quark_x1000(struct pci_dev *pdev)
+{
+       return pdev->vendor == PCI_VENDOR_ID_INTEL &&
+               pdev->device == PCI_DEVICE_ID_INTEL_QUARK_X1000_SOC;
+}
+
+/*
+ * 0x84 is the offset of in/out threshold register,
+ * and it is the same offset as the register of 'hostpc'.
+ */
+#define        intel_quark_x1000_insnreg01     hostpc
+
+/* Maximum usable threshold value is 0x7f dwords for both IN and OUT */
+#define INTEL_QUARK_X1000_EHCI_MAX_THRESHOLD   0x007f007f
 
 /* called after powerup, by probe or system-pm "wakeup" */
 static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
@@ -50,6 +65,16 @@ static int ehci_pci_reinit(struct ehci_hcd *ehci, struct pci_dev *pdev)
        if (!retval)
                ehci_dbg(ehci, "MWI active\n");
 
+       /* Reset the threshold limit */
+       if (is_intel_quark_x1000(pdev)) {
+               /*
+                * For the Intel QUARK X1000, raise the I/O threshold to the
+                * maximum usable value in order to improve performance.
+                */
+               ehci_writel(ehci, INTEL_QUARK_X1000_EHCI_MAX_THRESHOLD,
+                       ehci->regs->intel_quark_x1000_insnreg01);
+       }
+
        return 0;
 }