Linux-PCI Archive on lore.kernel.org
 help / color / Atom feed
From: Johannes Berg <johannes@sipsolutions.net>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	Manikanta Maddireddy <mmaddireddy@nvidia.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	robh+dt@kernel.org, mark.rutland@arm.com, jonathanh@nvidia.com,
	vidyas@nvidia.com, linux-tegra@vger.kernel.org,
	linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
	linux-pm@vger.kernel.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	linux-wireless@vger.kernel.org
Subject: Re: [PATCH V4 22/28] PCI: tegra: Access endpoint config only if PCIe link is up
Date: Wed, 19 Jun 2019 15:40:54 +0200
Message-ID: <634be6de5fd29064bd41540a5d93d1756c06a980.camel@sipsolutions.net> (raw)
In-Reply-To: <20190619133817.GA143205@google.com>

On Wed, 2019-06-19 at 08:38 -0500, Bjorn Helgaas wrote:

> > > > > How does rfkill work?  It sounds like it completely removes
> > > > > power from the wifi device, putting it in D3cold.  Is there
> > > > > any software notification other than the "Slot present pin
> > > > > change" (which looks like a Tegra-specific thing)?
> > 
> > Well, they said above it's a GPIO that controls it, so the software
> > already knows and doesn't really need an event?
> 
> Forgive my ignorance about rfkill.  At least in this Tegra case, it
> sounds like rfkill basically controls a power switch for the entire
> device, i.e., it doesn't merely turn off the radio portion of the
> device; it puts the entire PCI device in D3cold.

Sort of. The actual (hardware) implementation seems a bit more
complicated than a "power switch", but yes, that's the effect of it.

> Is rfkill integrated with the power management subsystem?  E.g., when
> lspci or X tries to read config space via pci_read_config(), does the
> pci_config_pm_runtime_get() in that path wake up the device?

No, that's the problem at hand AFAICT.

> IMO, if the struct pci_dev exists, we should be able to rely on the
> device actually being accessible (possibly after bringing it back to
> D0).  If rfkill only turns off the radio, leaving the PCI interface
> active, that would be fine -- in that case generic PCI things like
> lspci would work normally and it would be up to the driver to manage
> network-related things.
> 
> But if rfkill turns off PCI interface and the power management
> subsystem can't wake it up, I think we should unbind the driver and
> remove the pci_dev, so it wouldn't appear in lspci at all.

Right. That's being suggested here, but since the platform has no actual
hardware hotplug, that needs to be implemented in software.

The question at hand is *how* to actually achieve that.

I'm kind of arguing that it's not rfkill that achieves it, but the
underlying GPIO that toggles the device, since that GPIO could also be
bound to something other than an rfkill-gpio instance.

johannes


  reply index

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-16  5:52 [PATCH V4 00/28] Enable Tegra PCIe root port features Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 01/28] soc/tegra: pmc: Export tegra_powergate_power_on() Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 02/28] PCI: tegra: Handle failure cases in tegra_pcie_power_on() Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 03/28] PCI: tegra: Rearrange Tegra PCIe driver functions Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 04/28] PCI: tegra: Mask AFI_INTR in runtime suspend Manikanta Maddireddy
2019-06-04 13:08   ` Thierry Reding
2019-05-16  5:52 ` [PATCH V4 05/28] PCI: tegra: Fix PCIe host power up sequence Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 06/28] PCI: tegra: Add PCIe Gen2 link speed support Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 07/28] PCI: tegra: Advertise PCIe Advanced Error Reporting (AER) capability Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 08/28] PCI: tegra: Program UPHY electrical settings for Tegra210 Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 09/28] PCI: tegra: Enable opportunistic UpdateFC and ACK Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 10/28] PCI: tegra: Disable AFI dynamic clock gating Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 11/28] PCI: tegra: Process pending DLL transactions before entering L1 or L2 Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 12/28] PCI: tegra: Enable PCIe xclk clock clamping Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 13/28] PCI: tegra: Increase the deskew retry time Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 14/28] PCI: tegra: Add SW fixup for RAW violations Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 15/28] PCI: tegra: Update flow control timer frequency in Tegra210 Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 16/28] PCI: tegra: Set target speed as Gen1 before starting LTSSM Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 17/28] PCI: tegra: Fix PLLE power down issue due to CLKREQ# signal Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 18/28] PCI: tegra: Program AFI_CACHE* registers only for Tegra20 Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 19/28] PCI: tegra: Change PRSNT_SENSE IRQ log to debug Manikanta Maddireddy
2019-05-16  5:52 ` [PATCH V4 20/28] PCI: tegra: Use legacy IRQ for port service drivers Manikanta Maddireddy
2019-05-20 20:37   ` Bjorn Helgaas
2019-05-21  9:07     ` Manikanta Maddireddy
2019-05-16  5:53 ` [PATCH V4 21/28] PCI: tegra: Add AFI_PEX2_CTRL reg offset as part of soc struct Manikanta Maddireddy
2019-05-16  5:53 ` [PATCH V4 22/28] PCI: tegra: Access endpoint config only if PCIe link is up Manikanta Maddireddy
2019-06-04 13:14   ` Thierry Reding
2019-06-04 14:10     ` Manikanta Maddireddy
2019-06-10  4:38       ` Manikanta Maddireddy
2019-06-13 14:39         ` Lorenzo Pieralisi
2019-06-13 15:42           ` Thierry Reding
2019-06-17 10:01             ` Manikanta Maddireddy
2019-06-17 11:47               ` Thierry Reding
2019-06-17 19:30                 ` Bjorn Helgaas
2019-06-18  5:36                   ` Manikanta Maddireddy
2019-06-18 10:49                     ` Thierry Reding
2019-06-18 12:32                       ` Johannes Berg
2019-06-18 13:40                         ` Thierry Reding
2019-06-18 14:48                           ` Johannes Berg
2019-06-19 13:38                         ` Bjorn Helgaas
2019-06-19 13:40                           ` Johannes Berg [this message]
2019-05-16  5:53 ` [PATCH V4 23/28] dt-bindings: pci: tegra: Document PCIe DPD pinctrl optional prop Manikanta Maddireddy
2019-05-16  5:53 ` [PATCH V4 24/28] arm64: tegra: Add PEX DPD states as pinctrl properties Manikanta Maddireddy
2019-05-16  5:53 ` [PATCH V4 25/28] PCI: tegra: Put PEX CLK & BIAS pads in DPD mode Manikanta Maddireddy
2019-05-16  5:53 ` [PATCH V4 26/28] PCI: Add DT binding for "reset-gpios" property Manikanta Maddireddy
2019-06-17 11:30   ` Thierry Reding
2019-06-17 11:38     ` Manikanta Maddireddy
2019-06-17 11:48       ` Thierry Reding
2019-05-16  5:53 ` [PATCH V4 27/28] PCI: tegra: Add support for GPIO based PERST# Manikanta Maddireddy
2019-06-04 13:22   ` Thierry Reding
2019-06-13 15:24     ` Lorenzo Pieralisi
2019-06-14 10:37       ` Manikanta Maddireddy
2019-06-14 14:32         ` Lorenzo Pieralisi
2019-06-14 14:38           ` Manikanta Maddireddy
2019-06-14 14:50             ` Lorenzo Pieralisi
2019-06-14 14:56               ` Manikanta Maddireddy
2019-06-14 15:23               ` Thierry Reding
2019-06-14 15:59                 ` Lorenzo Pieralisi
2019-06-14 16:30                   ` Manikanta Maddireddy
2019-06-14 16:53                     ` Lorenzo Pieralisi
2019-06-14 17:23                       ` Manikanta Maddireddy
2019-06-17  9:48                         ` Lorenzo Pieralisi
2019-06-17 10:27                           ` Manikanta Maddireddy
2019-06-17 10:39                             ` Lorenzo Pieralisi
2019-06-17 11:29                         ` Thierry Reding
2019-06-17 11:26                       ` Thierry Reding
2019-05-16  5:53 ` [PATCH V4 28/28] PCI: tegra: Change link retry log level to debug Manikanta Maddireddy
2019-06-04 13:22   ` Thierry Reding
2019-05-16 13:12 ` [PATCH V4 00/28] Enable Tegra PCIe root port features Bjorn Helgaas
2019-05-17  8:38   ` Manikanta Maddireddy
2019-06-10  4:45 ` Manikanta Maddireddy
2019-06-10 17:33   ` Lorenzo Pieralisi

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=634be6de5fd29064bd41540a5d93d1756c06a980.camel@sipsolutions.net \
    --to=johannes@sipsolutions.net \
    --cc=devicetree@vger.kernel.org \
    --cc=helgaas@kernel.org \
    --cc=jonathanh@nvidia.com \
    --cc=linux-pci@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=linux-tegra@vger.kernel.org \
    --cc=linux-wireless@vger.kernel.org \
    --cc=lorenzo.pieralisi@arm.com \
    --cc=mark.rutland@arm.com \
    --cc=mmaddireddy@nvidia.com \
    --cc=rjw@rjwysocki.net \
    --cc=robh+dt@kernel.org \
    --cc=thierry.reding@gmail.com \
    --cc=vidyas@nvidia.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PCI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pci/0 linux-pci/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pci linux-pci/ https://lore.kernel.org/linux-pci \
		linux-pci@vger.kernel.org linux-pci@archiver.kernel.org
	public-inbox-index linux-pci


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pci


AGPL code for this site: git clone https://public-inbox.org/ public-inbox