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Subject: Re: [PATCH v2] cdc-wdm: fix "out-of-sync" due to missing
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From: Oliver Neukum <oneukum@suse.com>
To: =?ISO-8859-1?Q?Bj=F8rn?= Mork <bjorn@mork.no>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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Date: Sun, 10 Jul 2016 14:47:59 +0200
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On Sat, 2016-07-09 at 20:31 +0200, Bjørn Mork wrote:
> [removed the stable CC since this discussion isn't relevant to stable
>  anymore]
> 
> Oliver Neukum <oneukum@suse.com> writes:

[..]
> How about splitting the behaviour locally in cdc-wdm, keeping the
> current behaviour for CDC WDM devices and changing to "drain on open"
> for the netdev drivers?  Something like this plus the necessary logic
> dealing with the "drain_on_open" ("next_desc" is a label in wdm_probe):

Even better solution.

[..]
> Yes.  We could alternatively filter the EPIPE from read(), since it
> isn't supposed to happen anyway.  But it's not going to look less ugly :(

I'd rather not. Dropping errors really is evil.

> Execpt for the extreme ugliness, I don't think it will hurt to apply
> this unconditionally for all the network drivers using cdc-wdm, as long
> as it is limited to open only.

It is very hard to see how would can avoid it in the long run in resume.

> I certainly want to avoid any blacklist.  Device IDs are cheap in this
> market. The MBIM modems typically run Android and the device ID is
> configured in NVRAM for whatever OEM laptop vendor it is sold to.
> Having a catch-all class driver for MBIM is an absolute requirement.
> Making it depend on lists of devices is not an option, IMHO.

Obviously. I am just not optimistic that we can do without specific
exceptions in the long run.

	Regards
		Oliver