From: Bjorn Helgaas <helgaas@kernel.org>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: Vidya Sagar <vidyas@nvidia.com>,
mark.rutland@arm.com, heiko@sntech.de,
hayashi.kunihiko@socionext.com, maxime.ripard@bootlin.com,
catalin.marinas@arm.com, spujar@nvidia.com, will.deacon@arm.com,
kthota@nvidia.com, mperttunen@nvidia.com,
linux-tegra@vger.kernel.org, jonathanh@nvidia.com,
stefan.wahren@i2se.com, lorenzo.pieralisi@arm.com,
krzk@kernel.org, kishon@ti.com, tiwai@suse.de,
jagan@amarulasolutions.com, linux-pci@vger.kernel.org,
andy.gross@linaro.org, shawn.lin@rock-chips.com,
devicetree@vger.kernel.org, mmaddireddy@nvidia.com,
marc.w.gonzalez@free.fr, liviu.dudau@arm.com,
yue.wang@amlogic.com, enric.balletbo@collabora.com,
robh+dt@kernel.org, horms+renesas@verge.net.au,
bjorn.andersson@linaro.org, ezequiel@collabora.com,
linux-arm-kernel@lists.infradead.org, xiaowei.bao@nxp.com,
gustavo.pimentel@synopsys.com, linux-kernel@vger.kernel.org,
skomatineni@nvidia.com, jingoohan1@gmail.com, olof@lixom.net,
tpiepho@impinj.com, l.stach@pengutronix.de
Subject: Re: [PATCH 05/10] dt-bindings: PCI: tegra: Add device tree support for T194
Date: Tue, 2 Apr 2019 14:21:50 -0500 [thread overview]
Message-ID: <20190402192150.GF141706@google.com> (raw)
In-Reply-To: <20190401150740.GB4874@ulmo>
On Mon, Apr 01, 2019 at 05:07:40PM +0200, Thierry Reding wrote:
> On Mon, Apr 01, 2019 at 03:31:54PM +0530, Vidya Sagar wrote:
> > On 3/28/2019 6:45 PM, Thierry Reding wrote:
> > > On Tue, Mar 26, 2019 at 08:43:22PM +0530, Vidya Sagar wrote:
> > > > Add support for Tegra194 PCIe controllers. These controllers are based
> > > > on Synopsys DesignWare core IP.
> > > > +- nvidia,disable-aspm-states : controls advertisement of ASPM states
> > > > + bit-0 to '1' : disables advertisement of ASPM-L0s
> > > > + bit-1 to '1' : disables advertisement of ASPM-L1. This also disables
> > > > + advertisement of ASPM-L1.1 and ASPM-L1.2
> > > > + bit-2 to '1' : disables advertisement of ASPM-L1.1
> > > > + bit-3 to '1' : disables advertisement of ASPM-L1.2
> > >
> > > These seem more like configuration options rather than hardware
> > > description.
> > Yes. Since the platforms like Jetson-Xavier based on T194 are going to go in
> > open market, we are providing these configuration options and hence they are
> > optional
>
> Under what circumstances would we want to disable certain ASPM states?
> My understanding is that PCI device drivers can already disable
> individual ASPM states if they don't support them, so why would we ever
> want to disable advertisement of certain ASPM states?
The PCI core (not individual device drivers) configures ASPM, and if both
ends of the link implement the spec correctly, there is nothing the device
driver needs to do.
There *are* a few drivers that fiddle with ASPM-related things. I think
this is because either the core isn't doing things correctly and we haven't
bothered to fix the root cause, or the device itself is broken and we need
to disable something the hardware claims to support.
Bjorn
next prev parent reply other threads:[~2019-04-02 19:21 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-26 15:13 [PATCH 00/10] Add Tegra194 PCIe support Vidya Sagar
2019-03-26 15:13 ` [PATCH 01/10] PCI: save pci_bus pointer in pcie_port structure Vidya Sagar
2019-03-26 15:13 ` [PATCH 02/10] PCI: perform dbi regs write lock towards the end Vidya Sagar
2019-03-26 15:13 ` [PATCH 03/10] PCI: dwc: Move config space capability search API Vidya Sagar
2019-03-28 12:33 ` Thierry Reding
2019-04-01 11:46 ` Vidya Sagar
2019-03-26 15:13 ` [PATCH 04/10] PCI: Add #defines for PCIe spec r4.0 features Vidya Sagar
2019-03-26 15:13 ` [PATCH 05/10] dt-bindings: PCI: tegra: Add device tree support for T194 Vidya Sagar
2019-03-27 10:10 ` Jon Hunter
2019-03-27 10:53 ` Vidya Sagar
2019-03-28 13:15 ` Thierry Reding
2019-04-01 10:01 ` Vidya Sagar
2019-04-01 15:07 ` Thierry Reding
2019-04-02 11:41 ` Vidya Sagar
2019-04-02 14:35 ` Thierry Reding
2019-04-03 6:22 ` Vidya Sagar
2019-04-02 19:21 ` Bjorn Helgaas [this message]
2019-03-31 6:42 ` Rob Herring
2019-04-01 11:18 ` Vidya Sagar
2019-04-01 14:31 ` Thierry Reding
2019-04-02 9:16 ` Vidya Sagar
2019-04-02 14:20 ` Thierry Reding
2019-04-03 5:29 ` Vidya Sagar
2019-03-26 15:13 ` [PATCH 06/10] arm64: tegra: Add P2U and PCIe controller nodes to Tegra194 DT Vidya Sagar
2019-03-28 16:59 ` Thierry Reding
2019-04-01 12:37 ` Vidya Sagar
2019-03-26 15:13 ` [PATCH 07/10] arm64: tegra: Enable PCIe slots in P2972-0000 board Vidya Sagar
2019-03-26 15:13 ` [PATCH 08/10] phy: tegra: Add PCIe PIPE2UPHY support Vidya Sagar
2019-04-03 8:05 ` Kishon Vijay Abraham I
2019-04-03 10:45 ` Vidya Sagar
2019-03-26 15:13 ` [PATCH 09/10] PCI: tegra: Add Tegra194 PCIe support Vidya Sagar
2019-03-27 10:07 ` Jon Hunter
2019-03-29 20:52 ` Bjorn Helgaas
2019-04-02 7:17 ` Vidya Sagar
2019-04-02 14:14 ` Thierry Reding
2019-04-03 9:15 ` Vidya Sagar
2019-04-02 18:31 ` Bjorn Helgaas
2019-04-03 9:43 ` Vidya Sagar
2019-04-03 17:36 ` Bjorn Helgaas
2019-04-04 19:53 ` Vidya Sagar
2019-04-05 18:58 ` Bjorn Helgaas
2019-04-09 11:30 ` Vidya Sagar
2019-04-09 13:26 ` Bjorn Helgaas
2019-04-10 6:10 ` Vidya Sagar
2019-04-10 8:14 ` Liviu Dudau
2019-04-10 9:53 ` Vidya Sagar
2019-04-10 11:35 ` Liviu Dudau
2019-03-26 15:13 ` [PATCH 10/10] arm64: Add Tegra194 PCIe driver to defconfig Vidya Sagar
2019-03-27 10:08 ` Jon Hunter
2019-03-27 10:12 ` Vidya Sagar
2019-03-27 12:26 ` Jon Hunter
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