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usb: dwc3: core: improve reset sequence

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According to Synopsys Databook, we shouldn't be
relying on GCTL.CORESOFTRESET bit as that's only for
debugging purposes. Instead, let's use DCTL.CSFTRST
if we're OTG or PERIPHERAL mode.

Host side block will be reset by XHCI driver if
necessary. Note that this reduces amount of time
spent on dwc3_probe() by a long margin.

We're still gonna wait for reset to finish for a
long time (default to 1ms max), but tests show that
the reset polling loop executed at most 19 times
(modprobe dwc3 && modprobe -r dwc3 executed 1000
times in a row).

Suggested-by: Mian Yousaf Kaukab <yousaf.kaukab@intel.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Felipe Balbi 2016-03-11 10:51:52 +02:00
parent 9acdf4df2f
commit f59dcab176
1 changed files with 18 additions and 30 deletions
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48
drivers/usb/dwc3/core.c
View file

@ -67,23 +67,9 @@ void dwc3_set_mode(struct dwc3 *dwc, u32 mode)
static int dwc3_core_soft_reset(struct dwc3 *dwc)
{
u32 reg;
int retries = 1000;
int ret;
/* Before Resetting PHY, put Core in Reset */
reg = dwc3_readl(dwc->regs, DWC3_GCTL);
reg |= DWC3_GCTL_CORESOFTRESET;
dwc3_writel(dwc->regs, DWC3_GCTL, reg);
/* Assert USB3 PHY reset */
reg = dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0));
reg |= DWC3_GUSB3PIPECTL_PHYSOFTRST;
dwc3_writel(dwc->regs, DWC3_GUSB3PIPECTL(0), reg);
/* Assert USB2 PHY reset */
reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
reg |= DWC3_GUSB2PHYCFG_PHYSOFTRST;
dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
usb_phy_init(dwc->usb2_phy);
usb_phy_init(dwc->usb3_phy);
ret = phy_init(dwc->usb2_generic_phy);
@ -95,26 +81,28 @@ static int dwc3_core_soft_reset(struct dwc3 *dwc)
phy_exit(dwc->usb2_generic_phy);
return ret;
}
mdelay(100);
/* Clear USB3 PHY reset */
reg = dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0));
reg &= ~DWC3_GUSB3PIPECTL_PHYSOFTRST;
dwc3_writel(dwc->regs, DWC3_GUSB3PIPECTL(0), reg);
/*
* We're resetting only the device side because, if we're in host mode,
* XHCI driver will reset the host block. If dwc3 was configured for
* host-only mode, then we can return early.
*/
if (dwc->dr_mode == USB_DR_MODE_HOST)
return 0;
/* Clear USB2 PHY reset */
reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
reg &= ~DWC3_GUSB2PHYCFG_PHYSOFTRST;
dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
reg = dwc3_readl(dwc->regs, DWC3_DCTL);
reg |= DWC3_DCTL_CSFTRST;
dwc3_writel(dwc->regs, DWC3_DCTL, reg);
mdelay(100);
do {
reg = dwc3_readl(dwc->regs, DWC3_DCTL);
if (!(reg & DWC3_DCTL_CSFTRST))
return 0;
/* After PHYs are stable we can take Core out of reset state */
reg = dwc3_readl(dwc->regs, DWC3_GCTL);
reg &= ~DWC3_GCTL_CORESOFTRESET;
dwc3_writel(dwc->regs, DWC3_GCTL, reg);
udelay(1);
} while (--retries);
return 0;
return -ETIMEDOUT;
}
/**