usb: host: ehci-tegra: Wait for SOF before resume

Wait for Start Of Frame interrupt, then wait 20 us, before starting
port resume.  Workaround for hardware issue that can cause the SOF to
be sent out at the same time as the phy speed change.

Change-Id: I91ccbd2902448e87aa3cdf1970305de22efa1c10
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
index a516af28c29b745c7cf72f225f78bd5914d073e4..8acf0c4366f73a567912bdb0a61e612c80cc4b26 100644 (file)
--- a/drivers/usb/host/ehci-tegra.c
+++ b/drivers/usb/host/ehci-tegra.c
@@ -25,6 +25,8 @@
 
 #define TEGRA_USB_DMA_ALIGN 32
 
+#define STS_SRI        (1<<7)  /*      SOF Recieved    */
+
 struct tegra_ehci_hcd {
        struct ehci_hcd *ehci;
        struct tegra_usb_phy *phy;
@@ -71,6 +73,7 @@ static int tegra_ehci_hub_control(
        struct tegra_ehci_hcd *tegra = dev_get_drvdata(hcd->self.controller);
        u32 __iomem     *status_reg;
        u32             temp;
+       u32             usbsts_reg;
        unsigned long   flags;
        int             retval = 0;
 
@@ -144,6 +147,26 @@ static int tegra_ehci_hub_control(
 
                ehci->reset_done[wIndex-1] = jiffies + msecs_to_jiffies(25);
 
+               ehci_dbg(ehci, "%s:USBSTS = 0x%x", __func__,
+                       ehci_readl(ehci, &ehci->regs->status));
+               usbsts_reg = ehci_readl(ehci, &ehci->regs->status);
+               ehci_writel(ehci, usbsts_reg, &ehci->regs->status);
+               usbsts_reg = ehci_readl(ehci, &ehci->regs->status);
+               udelay(20);
+
+               if (handshake(ehci, &ehci->regs->status, STS_SRI, STS_SRI, 2000))
+                       pr_err("%s: timeout set for STS_SRI\n", __func__);
+
+               usbsts_reg = ehci_readl(ehci, &ehci->regs->status);
+               ehci_writel(ehci, usbsts_reg, &ehci->regs->status);
+
+               if (handshake(ehci, &ehci->regs->status, STS_SRI, 0, 2000))
+                       pr_err("%s: timeout clear STS_SRI\n", __func__);
+
+               if (handshake(ehci, &ehci->regs->status, STS_SRI, STS_SRI, 2000))
+                       pr_err("%s: timeout set STS_SRI\n", __func__);
+
+               udelay(20);
                temp &= ~(PORT_RWC_BITS | PORT_WAKE_BITS);
                /* start resume signalling */
                ehci_writel(ehci, temp | PORT_RESUME, status_reg);