linux-kernel - Re: [PATCH v3 2/7] regulator: qca6390: add support for QCA639x powerup sequence

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Date:   Tue, 6 Jul 2021 12:55:17 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Peter Chen <peter.chen@....com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-bluetooth@...r.kernel.org
Subject: Re: [PATCH v3 2/7] regulator: qca6390: add support for QCA639x
 powerup sequence

On Tue, Jul 06, 2021 at 09:54:03AM +0200, Ulf Hansson wrote:
> On Tue, 22 Jun 2021 at 00:32, Dmitry Baryshkov

> > Qualcomm QCA6390/1 is a family of WiFi + Bluetooth SoCs, with BT part
> > being controlled through the UART and WiFi being present on PCIe
> > bus. Both blocks share common power sources. Add device driver handling
> > power sequencing of QCA6390/1.

> Power sequencing of discoverable buses have been discussed several
> times before at LKML. The last attempt [1] I am aware of, was in 2017
> from Peter Chen. I don't think there is a common solution, yet.

This feels a bit different to the power sequencing problem - it's not
exposing the individual inputs to the device but rather is a block that
manages everything but needs a bit of a kick to get things going (I'd
guess that with ACPI it'd be triggered via AML).  It's in the same space
but it's not quite the same issue I think, something that can handle
control of the individual resources might still struggle with this.

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