From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: sashiko-reviews@lists.linux.dev, linux-pci@vger.kernel.org,
"Rafael J . Wysocki" <rafael@kernel.org>,
Lukas Wunner <lukas@wunner.de>,
Marco Nenciarini <mnencia@kcore.it>,
Michal Winiarski <michal.winiarski@intel.com>,
Ilpo Jarvinen <ilpo.jarvinen@linux.intel.com>,
Eric Chanudet <echanude@redhat.com>,
Jean Guyader <jean.guyader@gmail.com>,
Alex Williamson <alex@shazbot.org>,
Sinan Kaya <okaya@kernel.org>,
Mario Limonciello <superm1@kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
linux-kernel@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition
Date: Fri, 15 May 2026 13:26:59 +0200 [thread overview]
Message-ID: <CAJZ5v0gj4yG+ZEKHGhd0mjG+YA=2HuKnTvDrF7x1TQoC21JeHw@mail.gmail.com> (raw)
In-Reply-To: <20260514213811.GA434353@bhelgaas>
On Thu, May 14, 2026 at 11:38 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Thu, May 14, 2026 at 08:06:25PM +0000, sashiko-bot@kernel.org wrote:
> > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> > - [High] Ignored return value of `pci_dev_wait()` masks hardware readiness timeouts
> > --
> >
> > commit 606c3a6294de4df52ee7dc27a7792cef6c8f72c4
> > Author: Bjorn Helgaas <helgaas@kernel.org>
> >
> > PCI: Wait for device readiness after D3hot -> D0uninitialized transition
> >
> > This commit adds a call to pci_dev_wait() after transitioning a device from
> > D3hot to D0uninitialized. This ensures the device is ready to accept config
> > accesses, especially for devices with No_Soft_Reset == 0.
> >
> > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > > index 8f7cfcc000901..9d0fc9fbb76a0 100644
> > > --- a/drivers/pci/pci.c
> > > +++ b/drivers/pci/pci.c
> > [ ... ]
> > > @@ -1341,10 +1351,14 @@ int pci_power_up(struct pci_dev *dev)
> > > pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, 0);
> > >
> > > /* Mandatory transition delays; see PCI PM 1.2. */
> > > - if (state == PCI_D3hot)
> > > + if (state == PCI_D3hot) {
> > > pci_dev_d3_sleep(dev);
> > > - else if (state == PCI_D2)
> > > + if (!(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))
> > > + pci_dev_wait(dev, "power up D3hot->D0uninitialized",
> > > + PCIE_RESET_READY_POLL_MS);
> >
> > Is it safe to ignore the return value of pci_dev_wait() here?
> >
> > If the device times out or disconnects, pci_dev_wait() returns -ENOTTY. By
> > ignoring this error, pci_power_up() continues, unconditionally sets
> > dev->current_state = PCI_D0, and can return success (1 for need_restore).
> >
> > If pci_power_up() returns success, will callers like pci_back_from_sleep()
> > execute pci_restore_state() against an unresponsive device, which could
> > potentially trigger PCIe Master Aborts, AER events, or system crashes?
> >
> > Should pci_power_up() propagate the error from pci_dev_wait() to prevent
> > this?
>
> Good point. I think it should look like this instead:
>
> if (state == PCI_D3hot) {
> pci_dev_d3_sleep(dev);
> if (!(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET)) {
> ret = pci_dev_wait(dev, "power up D3hot->D0uninitialized",
> PCIE_RESET_READY_POLL_MS);
> if (ret) {
> pci_err(dev, "Not ready after soft reset\n");
> dev->current_state = PCI_D3cold;
> return -EIO;
> }
> }
> } else if (state == PCI_D2) {
> udelay(PCI_PM_D2_DELAY);
> }
This looks reasonable to me, thanks!
> > > + } else if (state == PCI_D2) {
> > > udelay(PCI_PM_D2_DELAY);
> > > + }
> > >
> > > end:
> > > dev->current_state = PCI_D0;
> >
> > --
> > Sashiko AI review · https://sashiko.dev/#/patchset/20260514153124.404060-1-bhelgaas@google.com?part=1
next prev parent reply other threads:[~2026-05-15 11:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-14 15:31 [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition Bjorn Helgaas
2026-05-14 18:52 ` Mario Limonciello
2026-05-14 20:06 ` sashiko-bot
2026-05-14 21:38 ` Bjorn Helgaas
2026-05-15 11:26 ` Rafael J. Wysocki [this message]
2026-05-15 11:41 ` Mika Westerberg
2026-05-15 11:57 ` Rafael J. Wysocki
2026-05-15 12:15 ` Mika Westerberg
2026-05-15 12:46 ` Lukas Wunner
2026-05-15 15:47 ` Bjorn Helgaas
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