linux-kernel - Re: [PATCH 01/14] Input: atmel_mxt_ts - do not pass suspend mode in platform data

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Message-ID: <20180316204002.GA24333@bm.shmanahar.org>
Date:   Fri, 16 Mar 2018 20:40:02 +0000
From:   Nick Dyer <nick@...anahar.org>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:     linux-input@...r.kernel.org, Benson Leung <bleung@...omium.org>,
        Olof Johansson <olof@...om.net>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/14] Input: atmel_mxt_ts - do not pass suspend mode in
 platform data

On Thu, Mar 15, 2018 at 04:56:21PM -0700, Dmitry Torokhov wrote:
> On Wed, Mar 14, 2018 at 08:51:24PM +0000, Nick Dyer wrote:
> > On Mon, Mar 12, 2018 at 12:08:54PM -0700, Dmitry Torokhov wrote:
> > > The way we are supposed to put controller to sleep and wake it up does not
> > > depend on the platform, but rather on controller itself. Controllers using
> > > T9 require manipulating T9 control register, while others, using newer
> > > T100, should be put to sleep by adjusting T7 power config.
> > 
> > I'm afraid this is actually a misconception. If you look at object table
> > for the older T9 device, you'll find it has the T7 object and it in fact
> > works exactly the same way as the T100-based device.
> > 
> > The MXT_SUSPEND_T9_CTRL is in there because on your older Pixel devices
> > the config saved into NVRAM on the touch controller has a zero byte in
> > the T9 CTRL setting, meaning the touch controller will never wake up
> > unless the driver knows to write 0x83 into it.
> 
> Ah, OK, I see. I would really like to drop this pdata->suspend_mode
> stuff and I do not want to create "pixel-screwed-up" property either...
> I guess for the time being I'll put a DMI quirk for Link to restore T9
> control method, and then look into cleaning it all up. We have quite a
> bit different code in chromeos kernel trees and I'd like to reconcile
> it.

Yes, it would be great to get rid of it. The driver does have the
ability to download configuration via the firmware loader interface. So
you would be able to grab a copy of the config by saving it with
mxt-app, tweak it to ensure that the T9 CTRL byte is set correctly, then
ship it somehow (presumably it could be added to linux-firmware). This
would override what's currently stored in NVRAM on all those units and
mean we could remove the T9_CTRL stuff.

I'm happy to talk you through sorting that out in more detail if you
want to give it a go. I don't have any Pixel 1 hardware available at the
moment, unfortunately.

N