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From: Rob Herring <robh+dt@kernel.org>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Jon Hunter <jonathanh@nvidia.com>,
	PCI <linux-pci@vger.kernel.org>,
	linux-tegra <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH v2 2/2] PCI: tegra: Remove PLL power supplies
Date: Mon, 27 Jul 2020 11:43:45 -0600
Message-ID: <CAL_JsqKztykYZDdeHgWEnwW_9rasDrNwz0Cz9K2Pe1BtmvembQ@mail.gmail.com> (raw)
In-Reply-To: <20200727172149.GA3683017@ulmo>

On Mon, Jul 27, 2020 at 11:21 AM Thierry Reding
<thierry.reding@gmail.com> wrote:
>
> On Mon, Jul 27, 2020 at 10:21:42AM -0600, Rob Herring wrote:
> > On Tue, Jun 23, 2020 at 8:55 AM Thierry Reding <thierry.reding@gmail.com> wrote:
> > >
> > > From: Thierry Reding <treding@nvidia.com>
> > >
> > > The Tegra PCI controller driver doesn't need to control the PLL power
> > > supplies directly, but rather uses the pads provided by the XUSB pad
> > > controller, which in turn is responsible for supplying power to the
> > > PLLs.
> > >
> > > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > > ---
> > >  drivers/pci/controller/pci-tegra.c | 10 ++--------
> > >  1 file changed, 2 insertions(+), 8 deletions(-)
> >
> > What's going to happen here with a new dtb and an old kernel? Is it
> > going to error out due to missing supplies?
>
> It's not going to error out but fallback to the "dummy" regulator, so
> this should be fine from a forwards-compatibility point of view. Though
> I didn't think we technically cared about that direction very much.

AIUI, SUSE ships newer DTs with stable kernels. Of course, the dtb's
shouldn't really come from the OS vendors, but you wouldn't want a
newer firmware (w/ dtb) to break your OS either.

In any case,

Reviewed-by: Rob Herring <robh@kernel.org>

Rob

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23 14:55 [PATCH v2 1/2] dt-bindings: pci: " Thierry Reding
2020-06-23 14:55 ` [PATCH v2 2/2] PCI: " Thierry Reding
2020-07-16 13:00   ` Thierry Reding
2020-07-16 14:07     ` Lorenzo Pieralisi
2020-07-16 15:06       ` Thierry Reding
2020-07-27 16:21   ` Rob Herring
2020-07-27 17:21     ` Thierry Reding
2020-07-27 17:43       ` Rob Herring [this message]
2020-07-16 12:59 ` [PATCH v2 1/2] dt-bindings: pci: " Thierry Reding
2020-07-17 10:48   ` Lorenzo Pieralisi
2020-07-27 16:17 ` Rob Herring
2020-07-28 10:20 ` Lorenzo Pieralisi

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