linux-kernel - Re: [PATCH 1/2] dt-bindings: net: bluetooth: nxp: add support for supply and reset

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Message-ID: <2b7f61a8-e91a-4b32-be1d-753a19e4d81f@leica-geosystems.com>
Date: Mon, 7 Oct 2024 12:58:34 +0000
From: POPESCU Catalin <catalin.popescu@...ca-geosystems.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Sherry Sun <sherry.sun@....com>,
	Amitkumar Karwar <amitkumar.karwar@....com>, 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>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>
CC: "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"m.felsch@...gutronix.de" <m.felsch@...gutronix.de>,
	GEO-CHHER-bsp-development <bsp-development.geo@...ca-geosystems.com>
Subject: Re: [PATCH 1/2] dt-bindings: net: bluetooth: nxp: add support for
 supply and reset

On 06/10/2024 13:33, Krzysztof Kozlowski wrote:
> [Some people who received this message don't often get email from krzk@...nel.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> This email is not from Hexagon’s Office 365 instance. Please be careful while clicking links, opening attachments, or replying to this email.
>
>
> On 06/10/2024 10:49, Sherry Sun wrote:
>>
>>> -----Original Message-----
>>> From: Catalin Popescu <catalin.popescu@...ca-geosystems.com>
>>> Sent: Friday, October 4, 2024 7:36 PM
>>> To: Amitkumar Karwar <amitkumar.karwar@....com>; Neeraj Sanjay Kale
>>> <neeraj.sanjaykale@....com>; marcel@...tmann.org;
>>> luiz.dentz@...il.com; robh@...nel.org; krzk+dt@...nel.org;
>>> conor+dt@...nel.org; p.zabel@...gutronix.de
>>> Cc: linux-bluetooth@...r.kernel.org; devicetree@...r.kernel.org; linux-
>>> kernel@...r.kernel.org; m.felsch@...gutronix.de; bsp-
>>> development.geo@...ca-geosystems.com; Catalin Popescu
>>> <catalin.popescu@...ca-geosystems.com>
>>> Subject: [PATCH 1/2] dt-bindings: net: bluetooth: nxp: add support for supply
>>> and reset
>>>
>>> Add support for chip power supply and chip reset/powerdown.
>>>
>>> Signed-off-by: Catalin Popescu <catalin.popescu@...ca-geosystems.com>
>>> ---
>>>   .../bindings/net/bluetooth/nxp,88w8987-bt.yaml        | 11 +++++++++++
>>>   1 file changed, 11 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
>>> bt.yaml b/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
>>> bt.yaml
>>> index 37a65badb448..8520b3812bd2 100644
>>> --- a/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
>>> bt.yaml
>>> +++ b/Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-
>>> bt.yaml
>>> @@ -34,6 +34,14 @@ properties:
>>>     firmware-name:
>>>       maxItems: 1
>>>
>>> +  vcc-supply:
>>> +    description:
>>> +      phandle of the regulator that provides the supply voltage.
>>> +
>>> +  reset-gpios:
>>> +    description:
>>> +      Chip powerdown/reset signal (PDn).
>>> +
>> Hi Catalin,
>>
>> For NXP WIFI/BT chip, WIFI and BT share the one PDn pin, which means that both wifi and BT controller will be powered on and off at the same time.
>> Taking the M.2 NXP WIFI/BT module as an example, pin56(W_DISABLE1) is connected to the WIFI/BT chip PDn pin, we has already controlled this pin in the corresponding PCIe/SDIO controller dts nodes.
>> It is not clear to me what exactly pins for vcc-supply and reset-gpios you describing here. Can you help understand the corresponding pins on M.2 interface as an example? Thanks.

Hi Sherry,

Regulators and reset controls being refcounted, we can then implement 
powerup sequence in both bluetooth/wlan drivers and have the drivers 
operate independently. This way bluetooth driver would has no dependance 
on the wlan driver for :

- its power supply

- its reset pin (PDn)

- its firmware (being downloaded as part of the combo firmware)

For the wlan driver we use mmc power sequence to drive the chip reset 
pin and there's another patchset that adds support for reset control 
into the mmc pwrseq simple driver.

> Please wrap your replies.
>
> It seems you need power sequencing just like Bartosz did for Qualcomm WCN.

Hi Krzysztof,

I'm not familiar with power sequencing, but looks like way more 
complicated than reset controls. So, why power sequencing is recommended 
here ? Is it b/c a supply is involved ?

>
> Best regards,
> Krzysztof
>