linux-kernel - Re: [PATCH v3 4/5] wifi: brcmfmac: Add optional lpo clock enable support

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Message-ID: <CAGb2v66Vk8SMs1TOs+80Jy5fXumuYqCx59Tzd_N7wJAfyysQcw@mail.gmail.com>
Date: Sun, 30 Jun 2024 17:15:00 +0800
From: Chen-Yu Tsai <wens@...nel.org>
To: Jacobe Zang <jacobe.zang@...ion.com>
Cc: Stefan Wahren <wahrenst@....net>, "robh@...nel.org" <robh@...nel.org>, 
	"krzk+dt@...nel.org" <krzk+dt@...nel.org>, "heiko@...ech.de" <heiko@...ech.de>, 
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	"brcm80211-dev-list.pdl@...adcom.com" <brcm80211-dev-list.pdl@...adcom.com>, Nick Xie <nick@...das.com>
Subject: Re: [PATCH v3 4/5] wifi: brcmfmac: Add optional lpo clock enable support

On Sun, Jun 30, 2024 at 5:10 PM Jacobe Zang <jacobe.zang@...ion.com> wrote:
>
> Hi Stefan,
>
> >> WiFi modules often require 32kHz clock to function. Add support to
> >> enable the clock to PCIe driver.
> > the low power clock is independent from the host interface like PCIe. So
> > the clock handling should move to the common code. Sorry, not i cannot
> > give a good suggestion, what's the best place for this.
>
> I think the clock is used by the PCIe device so enable it in this file. Also I checked
> use of clock which in spi[0] or sdio[0] device was enabled similarly to this.
>
> [0] https://lore.kernel.org/all/20210806081229.721731-4-claudiu.beznea@microchip.com/

You're looking at the wrong driver. For brcmfmac, the lpo clock is toggled
by the MMC pwrseq code. And for the Bluetooth side (where it really matters)
for UARTs, it is in drivers/bluetooth/hci_bcm.c. and documented in the
binding Documentation/devicetree/bindings/net/broadcom-bluetooth.yaml


ChenYu