From: Bryan O'Donoghue <bryan.odonoghue@xxxxxxxxx> 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@xxxxxxxxx> Signed-off-by: Alvin (Weike) Chen <alvin.chen@xxxxxxxxx> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Jingoo Han <jg1.han@xxxxxxxxxxx> --- Changlog v5: * Correct the wrong comment style. drivers/usb/host/ehci-pci.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c index 3e86bf4..ca7b964 100644 --- 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; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html