linux-kernel - RE: [PATCH] Input: elan_i2c - Reduce the resume time for new dev ices

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Message-ID: <004f01d7115e$3ba005e0$b2e011a0$@emc.com.tw>
Date:   Fri, 5 Mar 2021 09:24:05 +0800
From:   "jingle" <jingle.wu@....com.tw>
To:     "'Dmitry Torokhov'" <dmitry.torokhov@...il.com>
Cc:     "'linux-kernel'" <linux-kernel@...r.kernel.org>,
        "'linux-input'" <linux-input@...r.kernel.org>,
        "'phoenix'" <phoenix@....com.tw>,
        "'dave.wang'" <dave.wang@....com.tw>,
        "'josh.chen'" <josh.chen@....com.tw>
Subject: RE: [PATCH] Input: elan_i2c - Reduce the resume time for new dev ices

HI Dmitry:

In this case (in the newer parts behavior regarding need to reset after
powering them on), it is consistent with the original driver behavior with
any new or old device
(be called data->ops->initialize(client) : usleep(100) , etc.. , because
this times "data->quirks" is equal 0 at probe state.) 

THANKS
JINGLE

-----Original Message-----
From: Dmitry Torokhov [mailto:dmitry.torokhov@...il.com] 
Sent: Friday, March 05, 2021 8:55 AM
To: jingle.wu
Cc: linux-kernel; linux-input; phoenix; dave.wang; josh.chen
Subject: Re: [PATCH] Input: elan_i2c - Reduce the resume time for new dev
ices

Hi Jingle,

On Tue, Mar 02, 2021 at 09:04:57AM +0800, jingle.wu wrote:
> HI Dmitry:
> 
> So data->ops->initialize(client) essentially performs reset of the 
> controller (we may want to rename it even) and as far as I understand 
> you would want to avoid resetting the controller on newer devices, 
> right?
> 
> -> YES
> 
> My question is how behavior of older devices differ from the new ones 
> (are they stay in "undefined" state at power up) and whether it is 
> possible to determine if controller is in operating mode. For example, 
> what would happen on older devices if we call elan_query_product() 
> below without resetting the controller?
> 
> -> But there may be other problems, because ELAN can't test all the 
> -> older devices , so use quirk to divide this part.

OK, but could you please tell me what exactly was changed in the newer parts
behavior regarding need to reset after powering them on?

Thanks.

--
Dmitry