Re: [PATCH v7 0/8] Add support for handling PCIe M.2 Key E connectors in devicetree

[Manivannan Sadhasivam]

On Mon, Apr 13, 2026 at 03:54:59PM +0800, Chen-Yu Tsai wrote:
> Hi,
> 
> On Thu, Mar 26, 2026 at 01:36:28PM +0530, Manivannan Sadhasivam wrote:
> > Hi,
> > 
> > This series is the continuation of the series [1] that added the initial support
> > for the PCIe M.2 connectors. This series extends it by adding support for Key E
> > connectors. These connectors are used to connect the Wireless Connectivity
> > devices such as WiFi, BT, NFC and GNSS devices to the host machine over
> > interfaces such as PCIe/SDIO, USB/UART and NFC. This series adds support for
> > connectors that expose PCIe interface for WiFi and UART interface for BT. Other
> > interfaces are left for future improvements.
> 
> Thanks for working on this. I started playing with it now that it is in
> -next. The PCIe part works fine. I'm looking into how to fit the pwrseq
> 
> A couple questions:
> 
> - Given that this connector actually represents two devices, how do I
>   say I want the BT part to be a wakeup source, but not the WiFi part?
>   Does wakeup-source even work at this point?
> 

You can't use the DT property since the devices are not described in DT
statically. But you can still use the per-device 'wakeup' sysfs knob to enable
wakeup.

> - Are there plans to do the SDIO part?
> 

No, not at the moment. Feel free to take it up if you have the hardware and
motivation :)

> - The matching done in the M.2 connector driver for pwrseq_get() seems a
>   bit naive. It simply checks if the remote device in the OF graph is
>   the same as the requesting device.
> 
>   I think this would run into issues with USB hubs. If I have a USB hub
>   and two M.2 connectors, with both connectors connected to the same
>   hub, pwrseq_get() is going to always return only one of the instances.
>   This is because the USB hub has one device node with multiple OF graph
>   ports.
> 

Yeah, this is a known limitation. I'm trying to improve this part now and have
the WIP commits here: https://github.com/Mani-Sadhasivam/linux/tree/pwrseq-bt-en-fixes

Once the merge window closes, I'll submit these.

- Mani

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