On 09/22/2015 04:16 PM, Mian Yousaf Kaukab wrote:
From: Gregory Herrero <gregory.herrero@xxxxxxxxx>
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.
Hm, I don't see Gregory moving anything in this patch...
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@xxxxxxxxx>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@xxxxxxxxx>
Tested-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
---
drivers/usb/dwc2/hcd.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index de9d2e2..65044da 100644
--- 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;
MBR, Sergei
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
