On 02/15/2013 08:05 PM, Bjørn Mork wrote:
Alex Courbot <acourbot@xxxxxxxxxx> writes:
Unfortunately it does not, and fails the same way. On the other hand,
I do not see the issue when doing the following:
diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
index e4fad5e..1490029 100644
--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -238,8 +238,6 @@ int usb_wwan_write(struct tty_struct *tty, struct
usb_serial_port *port,
usb_pipeendpoint(this_urb->pipe), i);
err =
usb_autopm_get_interface_async(port->serial->interface);
- if (err < 0)
- break;
/* send the data */
memcpy(this_urb->transfer_buffer, buf, todo);
After doing this I don't see this issue anymore. It looks wrong
though. But it seems to work despite the obvious unbalance in autopm
calls that results.
If I understand you correctly, usb_wwan_write() failing here is not a
problem in itself, and the ack should just be sent again later?
That was what I thought looking (obviously too) briefly through this.
Most errors from usb_autopm_get_interface_async will be translated to
EIO before being returned by serial_write. I believe the userspace
application should deal with that. But maybe it just gives up? Should
we return EAGAIN or something instead?
I don't know. I am pretty clueless about these things...
Obviously not as much as I am. :) Checking what userspace is doing could
indeed be another trail.
But looking again, trying to guess why it works fine if you just ignore
the error. I believe that is because you then end up hitting this until
the interface is fully resumed:
if (intfdata->suspended) {
usb_anchor_urb(this_urb, &portdata->delayed);
spin_unlock_irqrestore(&intfdata->susp_lock, flags);
}
Yes, this seems to be exactly what is happening.
I am way out of my league here, but I wonder if pm_runtime_get()
shouldn't return -EINPROGRESS instead if there is a queued resume
request or an ongoing resume, regardless of disable_depth?
Maybe something like the completely untested:
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 3148b10..38e19ba 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -512,6 +512,9 @@ static int rpm_resume(struct device *dev, int rpmflags)
else if (dev->power.disable_depth == 1 && dev->power.is_suspended
&& dev->power.runtime_status == RPM_ACTIVE)
retval = 1;
+ else if (rpmflags & RPM_ASYNC && dev->power.request_pending &&
+ dev->power.request == RPM_REQ_RESUME)
+ retval = -EINPROGRESS;
else if (dev->power.disable_depth > 0)
retval = -EACCES;
if (retval)
---
usb_autopm_get_interface_async() will interprete EINPROGRESS as success,
so that would prevent this problem.
That sounds sensefull indeed. If the interface is soon to be resumed,
there should be no reason for usb_autopm_get_interface_async() to fail.
Let's give this a try and bring the idea to the PM people if it works.
In any case thanks a lot for the help, it is extremely useful.
Alex.
--
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
