Received-SPF: pass (google.com: domain of linux-kernel+bounces-55293-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Tue, 6 Feb 2024 10:00:57 -0600
From: Bjorn Helgaas <helgaas@kernel.org>
To: Ilpo =?utf-8?B?SsOkcnZpbmVu?= <ilpo.jarvinen@linux.intel.com>
Cc: Jian-Hong Pan <jhp@endlessos.org>, Johan Hovold <johan@kernel.org>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	David Box <david.e.box@linux.intel.com>,
	Damien Le Moal <dlemoal@kernel.org>,
	Niklas Cassel <cassel@kernel.org>,
	Nirmal Patel <nirmal.patel@linux.intel.com>,
	Jonathan Derrick <jonathan.derrick@linux.dev>,
	linux-pci@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	linux@endlessos.org
Subject: Re: [PATCH v2] PCI: vmd: Enable PCI PM's L1 substates of remapped
 PCIe Root Port and NVMe
Message-ID: <20240206160057.GA866439@bhelgaas>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <72b9ef46-851b-3555-0a43-8da4d4ab0fad@linux.intel.com>

On Tue, Feb 06, 2024 at 02:29:12PM +0200, Ilpo Järvinen wrote:
> On Fri, 2 Feb 2024, Jian-Hong Pan wrote:
> ...

> > +out_enable_link_state:
> > +	/*
> > +	 * Make PCI devices at D0 when enable PCI-PM L1 PM Substates from
> > +	 * Section 5.5.4 of PCIe Base Spec Revision 6.0
> 
> I don't understand what are you trying to say here? Are there some typos 
> or grammar errors or something entire missing from the comment?

This is about the fact that per sec 5.5.4, "If setting either or both
of the enable bits for PCI-PM L1 PM Substates, both ports must be
configured as described in this section while in D0."

We can wordsmith this a little, maybe:

  Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per
  PCIe r6.0, sec 5.5.4.

I look a little askance at having to do this separately from
pci_enable_link_state_locked(), but we can solve that elsewhere if
need be.

> > +	pci_set_power_state_locked(pdev, PCI_D0);
> > +	pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL);