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References: <20220718224033.GA1450714@bhelgaas> <20220720203705.GA1654821@bhelgaas>
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From:   Jim Quinlan <james.quinlan@broadcom.com>
Date:   Thu, 21 Jul 2022 10:56:53 -0400
Message-ID: <CA+-6iNyAXEYT=pc-i0RgtA2njD3f6yELNppJqy733c7O_rmgUg@mail.gmail.com>
Subject: Re: [PATCH v2 2/6] PCI: brcmstb: Split brcm_pcie_setup() into two funcs
To:     Bjorn Helgaas <helgaas@kernel.org>
Cc:     Jim Quinlan <jim2101024@gmail.com>,
        "open list:PCI NATIVE HOST BRIDGE AND ENDPOINT DRIVERS" 
        <linux-pci@vger.kernel.org>,
        Nicolas Saenz Julienne <nsaenz@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Cyril Brulebois <kibi@debian.org>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@broadcom.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Rob Herring <robh@kernel.org>,
        =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= <kw@linux.com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@lists.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>
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On Wed, Jul 20, 2022 at 4:37 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Mon, Jul 18, 2022 at 05:40:33PM -0500, Bjorn Helgaas wrote:
> > On Mon, Jul 18, 2022 at 01:14:25PM -0500, Bjorn Helgaas wrote:
> > > ...
> >
> > > So I think brcm_pcie_setup() does initialization that doesn't depend
> > > on the link or any downstream devices, and brcm_pcie_start_link() does
> > > things that depend on the link being up.  Right?
> > >
> > > If so, "start_link" might be a slight misnomer since AFAICT
> > > brcm_pcie_start_link() doesn't do anything to initiate link-up except
> > > maybe deasserting fundamental reset.  Some drivers start the LTSSM or
> > > explicitly enable link training, but brcm_pcie_start_link() doesn't
> > > seem to do anything like that.
> > >
> > > brcm_pcie_start_link() still does brcm_pcie_set_outbound_win().  Does
> > > that really depend on the link being up?  If that only affects the
> > > Root Port, maybe it could be done before link-up?
> >
> > What about the /* PCIe->SCB endian mode for BAR */ thing?  Does that
> > depend on the link being up?
> >
> > And the "Refclk from RC should be gated with CLKREQ#" part?  Does that
> > depend on the link being up?
> >
> > It seems obvious that brcm_pcie_set_ssc() and reading the negotiated
> > link speed and width depend on the link being up.
>
> Can we close on this?  Splitting into
Absolutely.

>
>   (a) stuff that can be initialized before the link is available and
>   (b) stuff that depends on the link
>
> makes good sense, but then (b) should only contain stuff that actually
> depends on the link.
>
> The "PCIe->SCB endian mode for BAR" *sounds* like something related to
> the primary side of the RP, not the link.
>
> Not sure about "Refclk from RC".  RC would certainly be primary side,
> but ASPM has to do with secondary (link) side.

I get the feedback, submission coming soon -- I was waiting for the
email thread to conclude.

Regards,
Jim Quinlan
Broadcom STB


>
> Bjorn

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