Commit 76c4c95d authored by Thinh Nguyen's avatar Thinh Nguyen Committed by Greg Kroah-Hartman
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usb: dwc3: gadget: Skip reading GEVNTSIZn 



The driver knows what it needs to set for GEVNTSIZn, and the controller
doesn't modify this register unless there's a hard reset. To save a few
microseconds of register read in read-modify-write operation, simply do
register write with the expected values. This can improve performance
when there are many interrupts generated, which the driver needs to
check and handle.

Signed-off-by: default avatarThinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/efddf4ee5821c4bc5ae7ad90d629ec7a0ebcbf9a.1638240306.git.Thinh.Nguyen@synopsys.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a02a26eb

drivers/usb/dwc3/gadget.c

+4 −8
Original line number Diff line number Diff line
@@ -4082,7 +4082,6 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt) 
	struct dwc3 *dwc = evt->dwc;

	irqreturn_t ret = IRQ_NONE;

	int left;

	u32 reg;



	left = evt->count;
@@ -4114,9 +4113,8 @@ static irqreturn_t dwc3_process_event_buf(struct dwc3_event_buffer *evt) 
	ret = IRQ_HANDLED;



	/* Unmask interrupt */

	reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0));

	reg &= ~DWC3_GEVNTSIZ_INTMASK;

	dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);

	dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0),

		    DWC3_GEVNTSIZ_SIZE(evt->length));



	if (dwc->imod_interval) {

		dwc3_writel(dwc->regs, DWC3_GEVNTCOUNT(0), DWC3_GEVNTCOUNT_EHB);
@@ -4145,7 +4143,6 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) 
	struct dwc3 *dwc = evt->dwc;

	u32 amount;

	u32 count;

	u32 reg;



	if (pm_runtime_suspended(dwc->dev)) {

		pm_runtime_get(dwc->dev);
@@ -4172,9 +4169,8 @@ static irqreturn_t dwc3_check_event_buf(struct dwc3_event_buffer *evt) 
	evt->flags |= DWC3_EVENT_PENDING;



	/* Mask interrupt */

	reg = dwc3_readl(dwc->regs, DWC3_GEVNTSIZ(0));

	reg |= DWC3_GEVNTSIZ_INTMASK;

	dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0), reg);

	dwc3_writel(dwc->regs, DWC3_GEVNTSIZ(0),

		    DWC3_GEVNTSIZ_INTMASK | DWC3_GEVNTSIZ_SIZE(evt->length));



	amount = min(count, evt->length - evt->lpos);

	memcpy(evt->cache + evt->lpos, evt->buf + evt->lpos, amount);