linux-kernel - Re: [PATCH 2/2] usb: dwc3: Add workaround for host mode VBUS glitch when boot

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Message-ID: <87y37lko78.fsf@linux.intel.com>
Date:   Wed, 16 Jan 2019 10:21:15 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     Ran Wang <ran.wang_1@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Cc:     "linux-usb\@vger.kernel.org" <linux-usb@...r.kernel.org>,
        "devicetree\@vger.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
        Ran Wang <ran.wang_1@....com>
Subject: Re: [PATCH 2/2] usb: dwc3: Add workaround for host mode VBUS glitch when boot


Hi,

Ran Wang <ran.wang_1@....com> writes:
> +static void dwc3_power_off_all_roothub_ports(struct dwc3 *dwc)
> +{
> +	int i, port_num;
> +	u32 reg, op_regs_base, offset;
> +	void __iomem		*xhci_regs;
> +
> +	/* xhci regs is not mapped yet, do it temperary here */
> +	if (dwc->xhci_resources[0].start) {
> +		xhci_regs = ioremap(dwc->xhci_resources[0].start,
> +				DWC3_XHCI_REGS_END);
> +		if (IS_ERR(xhci_regs)) {
> +			dev_err(dwc->dev, "Failed to ioremap xhci_regs\n");
> +			return;
> +		}
> +
> +		op_regs_base = HC_LENGTH(readl(xhci_regs));
> +		reg = readl(xhci_regs + XHCI_HCSPARAMS1);
> +		port_num = HCS_MAX_PORTS(reg);
> +
> +		for (i = 1; i <= port_num; i++) {
> +			offset = op_regs_base + XHCI_PORTSC_BASE + 0x10*(i-1);
> +			reg = readl(xhci_regs + offset);
> +			reg &= ~PORT_POWER;
> +			writel(reg, xhci_regs + offset);
> +		}
> +
> +		iounmap(xhci_regs);

why can't this be done during xhci_gen_setup()?

-- 
balbi

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