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

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Message-ID: <CAA8EJppSFb+Me6w5vUpmbogQ4DS2=15FmHu4nzGz2POWQPouwA@mail.gmail.com>
Date: Thu, 12 Sep 2024 17:49:31 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Konrad Dybcio <konradybcio@...nel.org>, Qiang Yu <quic_qianyu@...cinc.com>, 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, 12 Sept 2024 at 17:45, Manivannan Sadhasivam
<manivannan.sadhasivam@...aro.org> wrote:
>
> 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.

Patches 1-6 don't seem to depend on slot supplies, so they can be
submitted separately.

>
> - Mani
>
> > Konrad
>
> --
> மணிவண்ணன் சதாசிவம்



-- 
With best wishes
Dmitry