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

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Date:	Fri, 13 Feb 2015 11:08:38 +0200
From:	Mathias Nyman <mathias.nyman@...el.com>
To:	Sneeker Yeh <sneeker.yeh@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...aro.org>,
	Huang Rui <ray.huang@....com>,
	Kishon Vijay Abraham I <kishon@...com>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-omap@...r.kernel.org
CC:	Andy Green <andy.green@...aro.org>,
	Jassi Brar <jaswinder.singh@...aro.org>,
	Sneeker Yeh <Sneeker.Yeh@...fujitsu.com>
Subject: Re: [PATCH v3 1/5] xhci: add a quirk for device disconnection errata
 for Synopsis Designware USB3 core

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 
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