From: David Heinzelmann <heinzelmann.david@gmail.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: David Heinzelmann <heinzelmann.david@gmail.com>,
linux-usb@vger.kernel.org
Subject: Re: [PATCH] Check for changed device descriptors when a connection-change occurs before validating the connection.
Date: Fri, 20 Sep 2019 15:17:26 +0200 [thread overview]
Message-ID: <20190920131726.GA5913@dhe-pc> (raw)
In-Reply-To: <20190920085556.GB521576@kroah.com>
Hi,
sorry for the wrong patch format.
I am trying to detect a change. At the moment I think the change could be ignored if a
port connection-change occurs and the port status has again the 'PORT_CONNECTION' bit set.
I have a fx3 device which does a re-enumeration after a firmware download. This is working
as expected and I am seeing a 'remove event' and a 'add event' monitoring via udevadm. But
if I connect multiple devices at the same time via an usb hub I am sometimes not receiving
a 'remove event' and 'add event' for a single device.
I think the problem could be that when a device disconnects and the port connection-change
occurs and before the 'PORT_CONNECTION' bit is checked the device could already be
reconnected and the 'PORT_CONNECTION' bit is set. Therefore I think it is not correct to
resuscitate the exisiting device.
On Fri, Sep 20, 2019 at 10:55:56AM +0200, Greg KH wrote:
> On Fri, Sep 20, 2019 at 12:36:28PM +0200, David Heinzelmann wrote:
> > When a port connection-change occurs the hub driver tries to resuscitate an existing device.
> > Activated from a firmware download a usb device can re-enumerate with new or changed device
> > descriptors. Therefore it will be checked for changed device descriptors before the connection
> > is resuscitated and the connection-change event is ignored.
>
> Please wrap your lines at 72 columns :(
>
> Anyway, what problem are you trying to solve here? What is broken with
> how things work today? Are you trying to ignore a change that is
> currently showing up as a change, or trying to do the opposite?
>
> thanks,
>
> greg k-h
next prev parent reply other threads:[~2019-09-20 11:17 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-20 10:36 [PATCH] Check for changed device descriptors when a connection-change occurs before validating the connection David Heinzelmann
2019-09-20 8:55 ` Greg KH
2019-09-20 13:17 ` David Heinzelmann [this message]
2019-09-20 12:15 ` Greg KH
2019-09-20 15:33 ` David Heinzelmann
2019-09-23 14:49 ` Alan Stern
2019-09-24 10:01 ` David Heinzelmann
2019-09-25 14:20 ` Alan Stern
2019-09-30 7:26 ` David Heinzelmann
2019-09-30 14:25 ` Alan Stern
2019-10-04 13:23 ` David Heinzelmann
2019-10-04 14:17 ` Alan Stern
2019-10-07 8:47 ` David Heinzelmann
2019-10-07 14:01 ` Alan Stern
2019-10-07 15:35 ` Greg KH
2019-10-08 8:09 ` [PATCH v4] usb: hub: Check device descriptor before resusciation David Heinzelmann
2019-10-08 12:55 ` Greg KH
2019-10-08 16:10 ` David Heinzelmann
2019-10-08 15:17 ` Greg KH
2019-10-09 4:46 ` [PATCH v5] " David Heinzelmann
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