Re: [PATCH v3 1/5] xhci: add a quirk for device disconnection errata for Synopsis Designware USB3 core

[Mathias Nyman <mathias.nyman@intel.com>]

On 25.01.2015 10:13, Sneeker Yeh wrote:

Oh, and one more thing:

>  
> +static void xhci_try_to_clear_csc(struct usb_hcd *hcd, int dev_port_num)
> +{
> +	int max_ports;
> +	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
> +	__le32 __iomem **port_array;
> +	u32 status;
> +
> +	/* print debug info */
> +	if (hcd->speed == HCD_USB3) {
> +		max_ports = xhci->num_usb3_ports;
> +		port_array = xhci->usb3_ports;
> +	} else {
> +		max_ports = xhci->num_usb2_ports;
> +		port_array = xhci->usb2_ports;
> +	}
> +
> +	if (dev_port_num > max_ports) {
> +		xhci_err(xhci, "%s() port number invalid", __func__);
> +		return;
> +	}
> +	status = readl(port_array[dev_port_num - 1]);
> +
> +	/* write 1 to clear */
> +	if (!(status & PORT_CONNECT) && (status & PORT_CSC))
> +		writel(status & PORT_CSC, port_array[0]);

We don't want to write back all the bits we read from the PORTSC register.
Use the xhci_put_state_to_neutral(status) helper function to mask out some RW1C bits.

This in addition to writing to the correct PORTSC register as I previously mentioned.

-Mathias