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

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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>
This commit is contained in:
Bryan O'Donoghue 2014-07-02 01:58:18 -07:00 committed by Greg Kroah-Hartman
parent 4428524d8d
commit 6e693739e9
1 changed files with 25 additions and 0 deletions
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25
drivers/usb/host/ehci-pci.c
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@ -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;
}