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From:   Marge Yang <Marge.Yang@tw.synaptics.com>
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        margeyang <marge.yang@synaptics.corp-partner.google.com>,
        Wayne Chang <wayne.chang@tw.synaptics.com>,
        Marge Yang <Marge.Yang@tw.synaptics.com>
CC:     "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "hdegoede@redhat.com" <hdegoede@redhat.com>,
        "benjamin.tissoires@redhat.com" <benjamin.tissoires@redhat.com>,
        Kevin Chu <kevin.chu@tw.synaptics.com>,
        Derek Cheng <derek.cheng@tw.synaptics.com>,
        Vincent Huang <Vincent.huang@tw.synaptics.com>,
        Carl Yang <Carl.Yang@synaptics.com>,
        Ian Lu <Ian.Lu@tw.synaptics.com>,
        Darren Kang <Darren.Kang@tw.synaptics.com>
Subject: RE: [PATCH V2] Input: synaptics-rmi4 - filter incomplete relative
 packet.
Thread-Topic: [PATCH V2] Input: synaptics-rmi4 - filter incomplete relative
 packet.
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Date:   Mon, 15 Aug 2022 06:49:55 +0000
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Add Synaptics firmware member

Hi Dmitry,
	Update Synaptics firmware's comment.
[Wayne 08/15]
To address the transaction error case in the middle would potential lead to=
 the unexpected data transaction and latency between styk device and host d=
river.  F$03 didn't really parse any data packet but simply works as bridge=
 functionality to bypass the command and response packets between styk devi=
ce and driver.

Thanks
Marge Yang

-----Original Message-----
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>=20
Sent: Saturday, August 13, 2022 3:28 AM
To: margeyang <marge.yang@synaptics.corp-partner.google.com>
Cc: linux-input@vger.kernel.org; linux-kernel@vger.kernel.org; hdegoede@red=
hat.com; benjamin.tissoires@redhat.com; Marge Yang <Marge.Yang@tw.synaptics=
.com>; Derek Cheng <derek.cheng@tw.synaptics.com>; Vincent Huang <Vincent.h=
uang@tw.synaptics.com>
Subject: Re: [PATCH V2] Input: synaptics-rmi4 - filter incomplete relative =
packet.

CAUTION: Email originated externally, do not click links or open attachment=
s unless you recognize the sender and know the content is safe.


Hi Marge,

On Fri, Aug 12, 2022 at 04:43:25PM +0800, margeyang wrote:
> From: Marge Yang <marge.yang@synaptics.corp-partner.google.com>
>
> RMI4 F03 supports the Stick function,
> it's designed to support relative packet.
> This patch supports the following case.
> When relative packet can't be reported completely, it may miss one=20
> byte or two byte.
> New Synaptics firmware will report PARITY error.
> When timeout error or parity error happens,
> RMI4 driver will sends 0xFE command and ask FW to Re-send stick packet=20
> again.

My understanding is that F03 is intended to be a pass-through mechanism for=
 PS/2-compatible devices. In that spirit all protocol handling and validati=
on should happen in psmouse driver that attaches to a serio port provided b=
y F03.

Historically we did not pay attention to parity and frame errors for
PS/2 mice/touchpads (and for keyboards on x86) but we coudl add such code t=
here. Do we actually observe this with RMI devices? Can RMI firmware handle=
 this better instead?

Thanks.

--
Dmitry