linux-kernel - Re: [PATCH 8/8] PCI: qcom: Add support to PCIe slot power supplies

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Message-ID: <20240912144439.fnne4x7qvggveve2@thinkpad>
Date: Thu, 12 Sep 2024 20:14:39 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Konrad Dybcio <konradybcio@...nel.org>
Cc: Qiang Yu <quic_qianyu@...cinc.com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, vkoul@...nel.org,
	kishon@...nel.org, robh@...nel.org, andersson@...nel.org,
	krzk+dt@...nel.org, conor+dt@...nel.org, mturquette@...libre.com,
	sboyd@...nel.org, abel.vesa@...aro.org, quic_msarkar@...cinc.com,
	quic_devipriy@...cinc.com, kw@...ux.com, lpieralisi@...nel.org,
	neil.armstrong@...aro.org, linux-arm-msm@...r.kernel.org,
	linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
	linux-clk@...r.kernel.org
Subject: Re: [PATCH 8/8] PCI: qcom: Add support to PCIe slot power supplies

On Thu, Sep 12, 2024 at 04:15:56PM +0200, Konrad Dybcio wrote:
> On 12.09.2024 3:39 PM, Qiang Yu wrote:
> > 
> > On 9/11/2024 11:32 PM, Manivannan Sadhasivam wrote:
> >> On Wed, Sep 11, 2024 at 04:17:41PM +0800, Qiang Yu wrote:
> >>> On 8/28/2024 12:58 AM, Manivannan Sadhasivam wrote:
> >>>> On Tue, Aug 27, 2024 at 02:44:09PM +0300, Dmitry Baryshkov wrote:
> >>>>> On Tue, 27 Aug 2024 at 09:36, Qiang Yu <quic_qianyu@...cinc.com> wrote:
> >>>>>> On platform x1e80100 QCP, PCIe3 is a standard x8 form factor. Hence, add
> >>>>>> support to use 3.3v, 3.3v aux and 12v regulators.
> >>>>> First of all, I don't see corresponding bindings change.
> >>>>>
> >>>>> Second, these supplies power up the slot, not the host controller
> >>>>> itself. As such these supplies do not belong to the host controller
> >>>>> entry. Please consider using the pwrseq framework instead.
> >>>>>
> >>>> Indeed. For legacy reasons, slot power supplies were populated in the host
> >>>> bridge node itself until recently Rob started objecting it [1]. And it makes
> >>>> real sense to put these supplies in the root port node and handle them in the
> >>>> relevant driver.
> >>>>
> >>>> I'm still evaluating whether the handling should be done in the portdrv or
> >>>> pwrctl driver, but haven't reached the conclusion. Pwrctl seems to be the ideal
> >>>> choice, but I see a few issues related to handling the OF node for the root
> >>>> port.
> >>>>
> >>>> Hope I'll come to a conclusion in the next few days and will update this thread.
> >>>>
> >>>> - Mani
> >>>>
> >>>> [1] https://lore.kernel.org/lkml/20240604235806.GA1903493-robh@kernel.org/
> >>> Hi Mani, do you have any updates?
> >>>
> >> I'm working with Bartosz to add a new pwrctl driver for rootports. And we are
> >> debugging an issue currently. Unfortunately, the progress is very slow as I'm on
> >> vacation still.
> >>
> >> Will post the patches once it got resolved.
> >>
> >> - Mani
> > OK, thanks for your update.
> 
> Qiang, you can still resubmit the rest of the patches without having
> to wait on that to be resolved
> 

In that case, the slot supplies should be described in the PCIe bridge.

- Mani

> Konrad

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