[PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Bjorn Helgaas]

For a device that advertises No_Soft_Reset == 0, a transition from D3hot to
D0uninitialized is a soft reset, and the resulting internal device state is
undefined.

A transition from D3hot to D0uninitialized requires a minimum delay of
10 msec before accessing the device, but after that delay, the device is
permitted to respond to config requests with RRS completion status if it
needs more time to initialize (PCIe r7.0, sec 2.3.1).

Call pci_dev_wait() after pci_power_up() performs a D3hot->D0uninitialized
transition to ensure the device is ready to accept config accesses, as is
done after the similar transition in pci_pm_reset().

If the device is already ready, this is essentially a no-op except for one
additional config read.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/pci.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8f7cfcc00090..9d0fc9fbb76a 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1301,6 +1301,16 @@ int pci_power_up(struct pci_dev *dev)
 	pci_power_t state;
 	u16 pmcsr;
 
+	/*
+	 * When setting power state to D0, platform_pci_set_power_state()
+	 * ensures main power is on.  If it puts the device in D0, it also
+	 * completes any required delays after the transition; if it leaves
+	 * the device in D1, D2, or D3hot, we use the PM Capability to
+	 * transition to D0.
+	 *
+	 * In all cases, the device is either Configuration-Ready or
+	 * inaccessible upon return.
+	 */
 	platform_pci_set_power_state(dev, PCI_D0);
 
 	if (!dev->pm_cap) {
@@ -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);
+	} else if (state == PCI_D2) {
 		udelay(PCI_PM_D2_DELAY);
+	}
 
 end:
 	dev->current_state = PCI_D0;
-- 
2.51.0

Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Mario Limonciello]

On 5/14/26 10:31, Bjorn Helgaas wrote:
> For a device that advertises No_Soft_Reset == 0, a transition from D3hot to
> D0uninitialized is a soft reset, and the resulting internal device state is
> undefined.
> 
> A transition from D3hot to D0uninitialized requires a minimum delay of
> 10 msec before accessing the device, but after that delay, the device is
> permitted to respond to config requests with RRS completion status if it
> needs more time to initialize (PCIe r7.0, sec 2.3.1).
> 
> Call pci_dev_wait() after pci_power_up() performs a D3hot->D0uninitialized
> transition to ensure the device is ready to accept config accesses, as is
> done after the similar transition in pci_pm_reset().
> 
> If the device is already ready, this is essentially a no-op except for one
> additional config read.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>

BTW -

This reminds me of an attempt I had at solving a similar issue a few 
years back.  It would be a nice side effect if this actually solves that 
  issue too.

https://lore.kernel.org/linux-pci/20240823154023.360234-3-superm1@kernel.org/

> ---
>   drivers/pci/pci.c | 18 ++++++++++++++++--
>   1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 8f7cfcc00090..9d0fc9fbb76a 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1301,6 +1301,16 @@ int pci_power_up(struct pci_dev *dev)
>   	pci_power_t state;
>   	u16 pmcsr;
>   
> +	/*
> +	 * When setting power state to D0, platform_pci_set_power_state()
> +	 * ensures main power is on.  If it puts the device in D0, it also
> +	 * completes any required delays after the transition; if it leaves
> +	 * the device in D1, D2, or D3hot, we use the PM Capability to
> +	 * transition to D0.
> +	 *
> +	 * In all cases, the device is either Configuration-Ready or
> +	 * inaccessible upon return.
> +	 */
>   	platform_pci_set_power_state(dev, PCI_D0);
>   
>   	if (!dev->pm_cap) {
> @@ -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);
> +	} else if (state == PCI_D2) {
>   		udelay(PCI_PM_D2_DELAY);
> +	}
>   
>   end:
>   	dev->current_state = PCI_D0;

Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Bjorn Helgaas]

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);
    }

> > +	} 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

Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Rafael J. Wysocki]

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

Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Mika Westerberg]

On Thu, May 14, 2026 at 04:38:11PM -0500, Bjorn Helgaas 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;

I wonder if PCI_POWER_ERROR makes sense here?

>                             return -EIO;
>                     }
>             }
>     } else if (state == PCI_D2) {
>             udelay(PCI_PM_D2_DELAY);
>     }
> 
> > > +	} 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

Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Rafael J. Wysocki]

On Fri, May 15, 2026 at 1:41 PM Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
>
> On Thu, May 14, 2026 at 04:38:11PM -0500, Bjorn Helgaas 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;
>
> I wonder if PCI_POWER_ERROR makes sense here?

Not really, PCI_POWER_ERROR is mostly used by things like
"target_state" to indicate that nothing has been selected.

> >                             return -EIO;
> >                     }
> >             }
> >     } else if (state == PCI_D2) {
> >             udelay(PCI_PM_D2_DELAY);
> >     }
> >
> > > > + } 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

Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Mika Westerberg]

On Fri, May 15, 2026 at 01:57:13PM +0200, Rafael J. Wysocki wrote:
> On Fri, May 15, 2026 at 1:41 PM Mika Westerberg
> <mika.westerberg@linux.intel.com> wrote:
> >
> > On Thu, May 14, 2026 at 04:38:11PM -0500, Bjorn Helgaas 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;
> >
> > I wonder if PCI_POWER_ERROR makes sense here?
> 
> Not really, PCI_POWER_ERROR is mostly used by things like
> "target_state" to indicate that nothing has been selected.

Okay. Thanks.

Re: [PATCH v1] PCI: Wait for device readiness after D3hot -> D0uninitialized transition

[Lukas Wunner]

On Thu, May 14, 2026 at 04:38:11PM -0500, Bjorn Helgaas wrote:
> On Thu, May 14, 2026 at 08:06:25PM +0000, sashiko-bot@kernel.org wrote:
> > > +		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;
>                     }

pci_dev_wait() already emits a warning message on timeout, so the
additional pci_err() is probably not needed.  Otherwise the user
would see duplicate messages, i.e.:

  pci SSSS:BB:DD.F: not ready 60000ms after power up D3hot->D0uninitialized
  pci SSSS:BB:DD.F: Not ready after soft reset

Thanks,

Lukas