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Commit 726a4e41 authored by Manu Gautam's avatar Manu Gautam
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usb: xhci-plat: Add DT parameter to program xhci imod_interval 



XHCI allows interrupt moderation using imod_interval at 250ns
increments. Add DT parameter to specify this imod_value for
targets mainly with single CPU to reduce CPU interrupt loads.
This allows better balance between CPU usage and performance.

CRs-fixed: 1019219
Change-Id: Id479c162da6492caff4dd83de4054fee63b6abc5
Signed-off-by: default avatarManu Gautam <mgautam@codeaurora.org>
parent 450bd44d

Documentation/devicetree/bindings/usb/dwc3.txt

+2 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ Optional properties: 
 - snps,num-normal-evt-buffs: If present, specifies number of normal event buffers. Default is 1.

 - snps,num-gsi-evt-buffs: If present, specifies number of GSI based hardware accelerated event buffers.

	1 event buffer is needed per h/w accelerated endpoint.

 - xhci-imod-value: Interrupt moderation interval for host mode (in increments of 250nsec).



This is usually a subnode to DWC3 glue to which it is connected.
@@ -39,4 +40,5 @@ dwc3@4a030000 { 
	tx-fifo-resize;

	snps,usb3-u1u2-disable;

	snps,num-gsi-evt-buffs = <0x2>;

	xhci-imod-value = <4000>;

};

drivers/usb/dwc3/host.c

+5 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ int dwc3_host_init(struct dwc3 *dwc) 
	struct platform_device	*xhci;

	struct usb_xhci_pdata	pdata;

	int			ret;

	struct device_node	*node = dwc->dev->of_node;



	xhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);

	if (!xhci) {
@@ -53,6 +54,10 @@ int dwc3_host_init(struct dwc3 *dwc) 
#ifdef CONFIG_DWC3_HOST_USB3_LPM_ENABLE

	pdata.usb3_lpm_capable = 1;

#endif

	ret = of_property_read_u32(node, "xhci-imod-value",

					   &pdata.imod_interval);

	if (ret)

		pdata.imod_interval = 0;	/* use default xhci.c value */



	ret = platform_device_add_data(xhci, &pdata, sizeof(pdata));

	if (ret) {

drivers/usb/host/xhci-plat.c

+14 −0
Original line number Diff line number Diff line
@@ -129,6 +129,8 @@ static int xhci_plat_probe(struct platform_device *pdev) 
	struct clk              *clk;

	int			ret;

	int			irq;

	u32			temp, imod;

	unsigned long		flags;



	if (usb_disabled())

		return -ENODEV;
@@ -231,6 +233,18 @@ static int xhci_plat_probe(struct platform_device *pdev) 
	if (ret)

		goto put_usb3_hcd;



	/* override imod interval if specified */

	if (pdata && pdata->imod_interval) {

		imod = pdata->imod_interval & ER_IRQ_INTERVAL_MASK;

		spin_lock_irqsave(&xhci->lock, flags);

		temp = readl_relaxed(&xhci->ir_set->irq_control);

		temp &= ~ER_IRQ_INTERVAL_MASK;

		temp |= imod;

		writel_relaxed(temp, &xhci->ir_set->irq_control);

		spin_unlock_irqrestore(&xhci->lock, flags);

		dev_dbg(&pdev->dev, "%s: imod set to %u\n", __func__, imod);

	}



	ret = device_create_file(&pdev->dev, &dev_attr_config_imod);

	if (ret)

		dev_err(&pdev->dev, "%s: unable to create imod sysfs entry\n",

include/linux/usb/xhci_pdriver.h

+4 −0
Original line number Diff line number Diff line
@@ -19,9 +19,13 @@ 
 * @usb3_lpm_capable:	determines if this xhci platform supports USB3

 *			LPM capability

 *

 * @imod_interval:	minimum inter-interrupt interval. Specified in

 *			250nsec increments.

 *

 */

struct usb_xhci_pdata {

	unsigned	usb3_lpm_capable:1;

	unsigned	imod_interval;

};



#endif /* __USB_CORE_XHCI_PDRIVER_H */