Re: [PATCH net,stable] net: usb: Add HP hs2434 device to ZLP exception table

[Rob Gardner <robmatic@gmail.com>]

On Wed, 28 Aug 2013 18:23:32 -0400 (EDT)
David Miller <davem@davemloft.net> wrote:

> From: Rob Gardner <robmatic@gmail.com>
> Date: Sun, 25 Aug 2013 18:29:13 -0600
> 
> > From 018343ce2e679d97283fb51da25c43aa876d087a Mon Sep 17 00:00:00 2001
> > From: Rob Gardner <robmatic@gmail.com>
> > Date: Sun, 25 Aug 2013 16:02:23 -0600
> > Subject: [PATCH net,stable] net: usb: Add HP hs2434 device to ZLP exception table
> > 
> > This patch adds another entry (HP hs2434 Mobile Broadband) to the list
> > of exceptional devices that require a zero length packet in order to
> > function properly. This list was added in commit 844e88f0. The hs2434
> > is manufactured by Sierra Wireless, who also produces the MC7710,
> > which the ZLP exception list was created for in the first place. So
> > hopefully it is just this one producer's devices that will need this
> > workaround.
> > 
> > Tested on a DM1-4310NR HP notebook, which does not function without this
> > change.
> > 
> > Signed-off-by: Rob Gardner <robmatic@gmail.com>
> 
> Applied and queued up for -tablt, thanks.
> 
> On the topic of dealing with detection of this issue, how harmful is the
> workaround on chips that don't need it?  Will the driver not work in that
> case?


Bjørn says it could have a minor performance impact, but should not
cause any loss of functionality. I don't think there's any hard data on
what the performance cost might be but I know he would eventually like
to get rid of the exception list and live with the possible performance
impact if it means functionality for more devices.


-- 
Rob Gardner <robmatic@gmail.com>