linux-kernel - RE: [PATCH v1 2/2] Bluetooth: btnxpuart: Add GPIO support to power save feature

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Message-ID:
 <PAXPR04MB9185C5F6A37901CBFD956AE089712@PAXPR04MB9185.eurprd04.prod.outlook.com>
Date: Thu, 3 Oct 2024 15:49:25 +0000
From: Shenwei Wang <shenwei.wang@....com>
To: Neeraj Sanjay Kale <neeraj.sanjaykale@....com>, "marcel@...tmann.org"
	<marcel@...tmann.org>, "luiz.dentz@...il.com" <luiz.dentz@...il.com>,
	"robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, "conor+dt@...nel.org" <conor+dt@...nel.org>
CC: "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, Amitkumar Karwar
	<amitkumar.karwar@....com>, Rohit Fule <rohit.fule@....com>, Sherry Sun
	<sherry.sun@....com>, Luke Wang <ziniu.wang_1@....com>, Bough Chen
	<haibo.chen@....com>, LnxRevLi <LnxRevLi@....com>
Subject: RE: [PATCH v1 2/2] Bluetooth: btnxpuart: Add GPIO support to power
 save feature



> -----Original Message-----
> From: Neeraj Sanjay Kale <neeraj.sanjaykale@....com>
> Sent: Thursday, October 3, 2024 10:38 AM
> To: Shenwei Wang <shenwei.wang@....com>; marcel@...tmann.org;
> luiz.dentz@...il.com; robh@...nel.org; krzk+dt@...nel.org;
> conor+dt@...nel.org
> Cc: linux-bluetooth@...r.kernel.org; linux-kernel@...r.kernel.org;
> devicetree@...r.kernel.org; Amitkumar Karwar <amitkumar.karwar@....com>;
> Rohit Fule <rohit.fule@....com>; Sherry Sun <sherry.sun@....com>; Luke Wang
> <ziniu.wang_1@....com>; Bough Chen <haibo.chen@....com>; LnxRevLi
> <LnxRevLi@....com>
> Subject: RE: [PATCH v1 2/2] Bluetooth: btnxpuart: Add GPIO support to power
> save feature
> 
> The expected behavior is level trigger.
> The piece of code you are referring to is from power save init, where we are
> setting the initial value of GPIO as HIGH.
> However, if the FW is already present and running, with unknown power save
> state, a GPIO toggle ensures the chip wakes up, and FW and driver are in sync.
> 

If the module is already in a power-save state, waking it up only to immediately 
return it to power-save seems unnecessary. A more efficient approach would be 
to simply set the GPIO to LOW. This action should transition the module into a 
power-save state regardless of its previous condition.

Regards,
Shenwei

> Thanks,
> Neeraj