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

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Message-ID:
 <PAXPR04MB9185C2D3830832EA4E605E1C89772@PAXPR04MB9185.eurprd04.prod.outlook.com>
Date: Tue, 1 Oct 2024 19:36:03 +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: Tuesday, October 1, 2024 12:40 PM
> To: 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>; Neeraj Sanjay Kale
> <neeraj.sanjaykale@....com>; Sherry Sun <sherry.sun@....com>; Luke Wang
> <ziniu.wang_1@....com>; Bough Chen <haibo.chen@....com>; LnxRevLi
> <LnxRevLi@....com>
> Subject: [PATCH v1 2/2] Bluetooth: btnxpuart: Add GPIO support to power save
> feature
> 
> This adds support for driving the chip into sleep or wakeup with a GPIO.
> 
> If the device tree property h2c-ps-gpio is defined, the driver utilizes this GPIO for
> controlling the chip's power save state, else it  uses the default UART-break
> method.
> 
> Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@....com>
> ---
>  drivers/bluetooth/btnxpuart.c | 36 +++++++++++++++++++++++++++++++++--
>  1 file changed, 34 insertions(+), 2 deletions(-)
> 
>  	switch (psdata->h2c_wakeupmode) {
> +	case WAKEUP_METHOD_GPIO:
> +		pcmd.h2c_wakeupmode = BT_CTRL_WAKEUP_METHOD_GPIO;
> +		break;
>  	case WAKEUP_METHOD_DTR:
>  		pcmd.h2c_wakeupmode = BT_CTRL_WAKEUP_METHOD_DSR;
>  		break;
>  	psdata->h2c_ps_interval = PS_DEFAULT_TIMEOUT_PERIOD_MS;
> -	switch (DEFAULT_H2C_WAKEUP_MODE) {
> +
> +	switch (default_h2c_wakeup_mode) {
> +	case WAKEUP_METHOD_GPIO:
> +		psdata->h2c_wakeupmode = WAKEUP_METHOD_GPIO;
> +		gpiod_set_value_cansleep(psdata->h2c_ps_gpio, 1);
> +		usleep_range(5000, 10000);
> +		gpiod_set_value_cansleep(psdata->h2c_ps_gpio, 0);
> +		usleep_range(5000, 10000);
> +		break;

Based on the above GPIO operation sequences, it indicates that the target device likely responds to a 
falling edge (transition from high to low) as its wakeup trigger, is it?

In the cover letter, you mentioned " the driver puts the chip into power save state by driving the GPIO high, 
and wakes it up by driving the GPIO low". Seems the expected behavior is a level trigger.

This appears to be a discrepancy between the code implementation and the description in the cover letter 
regarding the wakeup mechanism. Can you please clarify it?

Thanks,
Shenwei

>  	case WAKEUP_METHOD_DTR:
>  		psdata->h2c_wakeupmode = WAKEUP_METHOD_DTR;
>  		serdev_device_set_tiocm(nxpdev->serdev, 0, TIOCM_DTR); @@
> -1279,6 +1308,9 @@ static int nxp_enqueue(struct hci_dev *hdev, struct sk_buff
> *skb)
>  				psdata->c2h_wakeup_gpio =
> wakeup_parm.c2h_wakeup_gpio;
>  				psdata->h2c_wakeup_gpio =
> wakeup_parm.h2c_wakeup_gpio;
>  				switch (wakeup_parm.h2c_wakeupmode) {
> +				case BT_CTRL_WAKEUP_METHOD_GPIO:
> +					psdata->h2c_wakeupmode =
> WAKEUP_METHOD_GPIO;
> +					break;
>  				case BT_CTRL_WAKEUP_METHOD_DSR:
>  					psdata->h2c_wakeupmode =
> WAKEUP_METHOD_DTR;
>  					break;
> --
> 2.25.1