usb: dwc2: host: wait 3ms for controller stabilization

Some high speed mass storage devices fail to enumerate with following
error:

Cannot enable port %i.  Maybe the USB cable is bad?

This happens only when the device is plugged while the controller
is in hibernation state. After exiting hibernation, the controller
detects the device as a low speed device and fail to enumerate it.

Problem occurs only if HPRT0.PWR bit is programmed in a too short
delay after exiting hibernation. Dumping hprt register in
_dwc2_hcd_resume() directly after dwc2_exit_hibernation() shows that
HPRT0.LNSTS (D+/D- level) becomes valid approximately 2ms after
exiting hibernation.

Since dwc2_exit_hibernation() is called from atomic context, move the
delay out of this function.

Delay value is experimental and not mentioned in Synopsys
documentation. To be on the safe side 3ms delay is used.

Signed-off-by: Gregory Herrero <gregory.herrero@intel.com>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@intel.com>
Tested-by: Robert Baldyga <r.baldyga@samsung.com>
Tested-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Tested-by: John Youn <johnyoun@synopsys.com>
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index de9d2e2..65044da 100644 (file)
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -2472,6 +2472,9 @@ static int _dwc2_hcd_resume(struct usb_hcd *hcd)
                spin_unlock_irqrestore(&hsotg->lock, flags);
                dwc2_port_resume(hsotg);
        } else {
+               /* Wait for controller to correctly update D+/D- level */
+               usleep_range(3000, 5000);
+
                /*
                 * Clear Port Enable and Port Status changes.
                 * Enable Port Power.
@@ -2479,7 +2482,7 @@ static int _dwc2_hcd_resume(struct usb_hcd *hcd)
                dwc2_writel(HPRT0_PWR | HPRT0_CONNDET |
                                HPRT0_ENACHG, hsotg->regs + HPRT0);
                /* Wait for controller to detect Port Connect */
-               mdelay(5);
+               usleep_range(5000, 7000);
        }
 
        return ret;