From: Marc Zyngier <maz@kernel.org>
To: Hector Martin <marcan@marcan.st>
Cc: "Rob Herring" <robh@kernel.org>,
"Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
"Krzysztof Wilczyński" <kw@linux.com>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Alyssa Rosenzweig" <alyssa@rosenzweig.io>,
"Sven Peter" <sven@svenpeter.dev>,
PCI <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] PCI: apple: Add support for optional PWREN GPIO
Date: Thu, 05 May 2022 16:38:26 +0100 [thread overview]
Message-ID: <87wnf06lcd.wl-maz@kernel.org> (raw)
In-Reply-To: <57e47786-0b99-646e-9e73-694e47d14cf5@marcan.st>
On Wed, 04 May 2022 04:36:02 +0100,
Hector Martin <marcan@marcan.st> wrote:
[...]
>
> So it'd go something like this:
>
> - apcie driver, on slot activation, sees a pwren gpio/reg and powers it
> on prior to bringing up the link (and marks that port as d3cold supported)
> - sdhci-pci driver, on probe, sees an external card detect GPIO declared
> and considers that license to call pci_d3cold_enable and enable
> runtime-pm (since it won't need the internal card detect IRQ/GPIO)
> - No SD card is inserted, so SD driver goes into runtime suspend and
> saves whatever controller state it needs
> - PCI core saves whatever config space stuff it needs to save, SD
> controller is powered down via GPIO
I haven't quite found yet how this goes, but I can't say I tried in
anger. I guess that the root port device has to provide some standard
PM callbacks that would further tickle the regulator?
> - SD card is inserted, SMC GPIO IRQ notifies SD driver
> - SD driver goes out of runtime suspend
> - PCI core powers on controller, re-establishes link, restores config space
> - SD driver restores host controller registers and discovers the new card
>
> No new APIs, this is all existing kernel stuff. PCI manages slot power
> same as it does on ACPI systems (that support it), driver interacts with
> it via runtime-pm and the d3cold control stuff.
>
> I'm tempted to prototype this today and see how it goes...
Well, let us know how that goes.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
next prev parent reply other threads:[~2022-05-05 15:38 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-02 9:38 [PATCH 0/3] PCI: apple: PWREN GPIO support & related fixes Hector Martin
2022-05-02 9:38 ` [PATCH 1/3] PCI: apple: GPIO handling nitfixes Hector Martin
2022-05-02 10:20 ` Marc Zyngier
2022-05-02 12:16 ` Hector Martin
2022-05-02 11:39 ` Greg KH
2022-05-02 9:38 ` [PATCH 2/3] PCI: apple: Probe all GPIOs for availability first Hector Martin
2022-05-02 10:23 ` Marc Zyngier
2022-05-02 9:38 ` [PATCH 3/3] PCI: apple: Add support for optional PWREN GPIO Hector Martin
2022-05-02 10:31 ` Marc Zyngier
2022-05-02 12:15 ` Hector Martin
2022-05-02 15:14 ` Rob Herring
2022-05-02 15:32 ` Hector Martin
2022-05-03 3:20 ` Hector Martin
2022-05-04 0:33 ` Rob Herring
2022-05-04 3:36 ` Hector Martin
2022-05-05 15:38 ` Marc Zyngier [this message]
2022-05-02 20:59 Mark Kettenis
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