Hello!
On 10/20/2017 12:54 PM, Uwe Kleine-König wrote:
ehci_hub_control does the following related to overcurrent handling
(simplified):
temp = ehci_readl(ehci, status_reg);
if (temp & PORT_OCC) {
status |= USB_PORT_STAT_C_OVERCURRENT << 16;
if (temp & PORT_OC) {
ehci_port_power(ehci, wIndex, false);
temp = ehci_readl(ehci, status_reg);
}
}
if (temp & PORT_OC)
status |= USB_PORT_STAT_OVERCURRENT;
At least on my i.MX25 based machine rereading the PORTSC register after
port power was removed doesn't yield PORT_OC any more. The result is
that repeatedly changes related to over-current
(status |= USB_PORT_STAT_C_OVERCURRENT << 16) are reported, but
USB_PORT_STAT_OVERCURRENT doesn't toggle as expected and is always
unset. As a side effect the message
dev_err(&port_dev->dev, "over-current condition\n");
from drivers/usb/core/hub.c's port_event() never makes it to the user.
Rereading the value was introduced with the rationale:
I also think that the fact that we've cut off the port power
should be reflected in the result of GetPortStatus request
immediately, hence I'm adding a PORTSCn register readback after
write...
The v1 of that patch just unset PORT_POWER, Alan then sugested to re-read
the PORTSCn register and I agreed. :-)
As there are no further expected changes, just mask the PORT_POWER bit
instead of rereading the register.
An alternative would be to check for PORT_OC before checking for
PORT_OCC.
Fixes: 81463c1d7071 ("EHCI: only power off port if over-current is active")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
---
drivers/usb/host/ehci-hub.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
index df169c8e7225..08f59654654b 100644
--- a/drivers/usb/host/ehci-hub.c
+++ b/drivers/usb/host/ehci-hub.c
@@ -1031,7 +1031,7 @@ int ehci_hub_control(
spin_unlock_irqrestore(&ehci->lock, flags);
ehci_port_power(ehci, wIndex, false);
spin_lock_irqsave(&ehci->lock, flags);
- temp = ehci_readl(ehci, status_reg);
+ temp |= ~PORT_POWER;
You surely meant '&='?
MBR, Sergei
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