linux-kernel - Re: [PATCH] Add a quirk for the Dell XPS 13 (2015) when in PS/2 mode.

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Message-ID: <54EE1917.4020805@dell.com>
Date:	Wed, 25 Feb 2015 12:48:55 -0600
From:	Mario Limonciello <mario_limonciello@...l.com>
To:	Pali Rohár <pali.rohar@...il.com>
CC:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	Rob <robr.bensson@...il.com>
Subject: Re: [PATCH] Add a quirk for the Dell XPS 13 (2015) when in PS/2 mode.


On 02/20/2015 02:41 PM, Pali Rohár wrote:
> On Friday 20 February 2015 20:56:23 Mario Limonciello wrote:
>
> resetafter=0 means to never reset (even if driver receive e.g
> thousand invalid packets). I think this is very dangerous if
> there will be other bugs either in linux driver or some other HW
> problems.
>
> For ALPS issue I added resetafter = pktsize * 2 (Allow 2 invalid
> packets without resetting device). Cannot you find something
> similar for synaptics touchpads on XPS? (pktsize for ALPS is 6,
> no idea how big are synaptics packets).
>
Pali,

I've done some experimentation with increasing the size to resetafter to up to pktsize * 4.  It will decrease the number of occurrences of this problem, but the problem still occurs eventually.  pktsize for synaptics is 6 as well.  Would you recommend to continue to go higher than that?  Since out_of_sync_cnt is reset when a full packet gets received, some arbitrarily high number should likely fix it to.

That being said, if you try to more closely follow what Windows does for the mouse, it's not issuing a reconnect no matter how much bad data is received.
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