[PATCH v2 0/4] Prepare Armada 3700 PCIe suspend to RAM support

[PATCH v2 0/4] Prepare Armada 3700 PCIe suspend to RAM support

[Miquel Raynal]

Hello,

As part of an effort to bring suspend to RAM support to the Armada
3700 SoC (main target: ESPRESSObin board), there are small things to
do in the Armada 3700 peripherals clock driver:

* On this SoC, the PCIe controller gets fed by a gated clock in the
  south bridge. This clock is missing in the current driver, patch 1
  adds it.

* Because of a constraint in the PCI core, the resume function of a
  PCIe controller driver must be run at an early stage
  (->suspend/resume_noirq()), before the core tries to ->read/write()
  in the PCIe registers to do more configuration. Hence, the PCIe
  clock must be resumed before. This is enforced thanks to two
  changes:
  1/ Add device links to the clock framework. This enforce order in
     the PM core: the clocks are resumed before the consumers. Series
     has been posted, see [1].
  2/ Even with the above feature, the clock's resume() callback is
     called after the PCI controller's resume_noirq() callback. The
     only way to fix this is to change the "priority" of the clock
     suspend/resume callbacks. This is done in patch 2.

* The bindings are updated with the PCI clock in patch 4 while patch 3
  is just a typo correction in the same file.

If there is anything unclear please feel free to ask.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-November/614527.html

Thanks,
Miquèl

Changes in v2:
==============
* Rebased on top of v5.2-rc1.
* Added Rob's R-by tags.
* No change on the "change suspend/resume time" patch as, despite my
  pings, I got no answer and IMHO the proposed approach is entirely
  valid.


Miquel Raynal (4):
  clk: mvebu: armada-37xx-periph: add PCIe gated clock
  clk: mvebu: armada-37xx-periph: change suspend/resume time
  dt-bindings: clk: armada3700: fix typo in SoC name
  dt-bindings: clk: armada3700: document the PCIe clock

 .../devicetree/bindings/clock/armada3700-periph-clock.txt   | 5 +++--
 drivers/clk/mvebu/armada-37xx-periph.c                      | 6 ++++--
 2 files changed, 7 insertions(+), 4 deletions(-)

-- 
2.19.1

[PATCH v2 1/4] clk: mvebu: armada-37xx-periph: add PCIe gated clock

[Miquel Raynal]

The PCIe clock is a gated clock which has the same source as GbE0
(both IPs share a set of registers). This source clock is called
'gbe_core' in the driver.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/clk/mvebu/armada-37xx-periph.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c
index 4c20093a42fb..1e18c5a875bd 100644
--- a/drivers/clk/mvebu/armada-37xx-periph.c
+++ b/drivers/clk/mvebu/armada-37xx-periph.c
@@ -304,6 +304,7 @@ PERIPH_CLK_GATE_DIV(gbe_bm, 12, DIV_SEL1, 0, clk_table1);
 PERIPH_CLK_FULL_DD(sdio, 11, 14, DIV_SEL0, DIV_SEL0, 3, 6);
 PERIPH_CLK_FULL_DD(usb32_usb2_sys, 16, 16, DIV_SEL0, DIV_SEL0, 9, 12);
 PERIPH_CLK_FULL_DD(usb32_ss_sys, 17, 18, DIV_SEL0, DIV_SEL0, 15, 18);
+static PERIPH_GATE(pcie, 14);
 
 static struct clk_periph_data data_sb[] = {
 	REF_CLK_MUX_DD(gbe_50),
@@ -319,6 +320,7 @@ static struct clk_periph_data data_sb[] = {
 	REF_CLK_FULL_DD(sdio),
 	REF_CLK_FULL_DD(usb32_usb2_sys),
 	REF_CLK_FULL_DD(usb32_ss_sys),
+	REF_CLK_GATE(pcie, "gbe_core"),
 	{ },
 };
 
-- 
2.19.1

[PATCH v2 2/4] clk: mvebu: armada-37xx-periph: change suspend/resume time

[Miquel Raynal]

Armada 3700 PCIe IP relies on the PCIe clock managed by this
driver. For reasons related to the PCI core's organization when
suspending/resuming, PCI host controller drivers must reconfigure
their register at suspend_noirq()/resume_noirq() which happens after
suspend()/suspend_late() and before resume_early()/resume().

Device link support in the clock framework enforce that the clock
driver's resume() callback will be called before the PCIe
driver's. But, any resume_noirq() callback will be called before all
the registered resume() callbacks.

The solution to support PCIe resume operation is to change the
"priority" of this clock driver PM callbacks to "_noirq()".

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/clk/mvebu/armada-37xx-periph.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c
index 1e18c5a875bd..bee45e43a85f 100644
--- a/drivers/clk/mvebu/armada-37xx-periph.c
+++ b/drivers/clk/mvebu/armada-37xx-periph.c
@@ -715,8 +715,8 @@ static int __maybe_unused armada_3700_periph_clock_resume(struct device *dev)
 }
 
 static const struct dev_pm_ops armada_3700_periph_clock_pm_ops = {
-	SET_SYSTEM_SLEEP_PM_OPS(armada_3700_periph_clock_suspend,
-				armada_3700_periph_clock_resume)
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(armada_3700_periph_clock_suspend,
+				      armada_3700_periph_clock_resume)
 };
 
 static int armada_3700_periph_clock_probe(struct platform_device *pdev)
-- 
2.19.1

[PATCH v2 3/4] dt-bindings: clk: armada3700: fix typo in SoC name

[Miquel Raynal]

This documentation is about Armada 3700 SoCs.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../devicetree/bindings/clock/armada3700-periph-clock.txt     | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt b/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt
index 1e3370ba189f..85972715e593 100644
--- a/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt
+++ b/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt
@@ -9,7 +9,7 @@ bridge.
 The peripheral clock consumer should specify the desired clock by
 having the clock ID in its "clocks" phandle cell.
 
-The following is a list of provided IDs for Armada 370 North bridge clocks:
+The following is a list of provided IDs for Armada 3700 North bridge clocks:
 ID	Clock name	Description
 -----------------------------------
 0	mmc		MMC controller
@@ -30,7 +30,7 @@ ID	Clock name	Description
 15	eip97		EIP 97
 16	cpu		CPU
 
-The following is a list of provided IDs for Armada 370 South bridge clocks:
+The following is a list of provided IDs for Armada 3700 South bridge clocks:
 ID	Clock name	Description
 -----------------------------------
 0	gbe-50		50 MHz parent clock for Gigabit Ethernet
-- 
2.19.1

[PATCH v2 4/4] dt-bindings: clk: armada3700: document the PCIe clock

[Miquel Raynal]

Add a reference to the missing PCIe clock managed by this IP. The
clock resides in the south bridge.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../devicetree/bindings/clock/armada3700-periph-clock.txt        | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt b/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt
index 85972715e593..fbf58c443c04 100644
--- a/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt
+++ b/Documentation/devicetree/bindings/clock/armada3700-periph-clock.txt
@@ -46,6 +46,7 @@ ID	Clock name	Description
 10	sdio		SDIO
 11	usb32-sub2-sys	USB 2 clock
 12	usb32-ss-sys	USB 3 clock
+13	pcie		PCIe controller
 
 Required properties:
 
-- 
2.19.1

Re: [PATCH v2 2/4] clk: mvebu: armada-37xx-periph: change suspend/resume time

[Bjorn Helgaas]

From: Miquel Raynal <miquel.raynal@bootlin.com>
Date: Tue, May 21, 2019 at 8:04 AM
To: Michael Turquette, Stephen Boyd, Rob Herring, Mark Rutland
Cc: <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>, Thomas
Petazzoni, Antoine Tenart, Gregory Clement, Maxime Chevallier, Nadav
Haklai, Bjorn Helgaas, Rafael J . Wysocki, <linux-pm@vger.kernel.org>,
Miquel Raynal

> Armada 3700 PCIe IP relies on the PCIe clock managed by this
> driver. For reasons related to the PCI core's organization when
> suspending/resuming, PCI host controller drivers must reconfigure
> their register at suspend_noirq()/resume_noirq() which happens after
> suspend()/suspend_late() and before resume_early()/resume().

"For reasons related to the PCI core's organization" manages to
suggest that this change wouldn't be needed if only the PCI core did
something differently, without actually being specific about what it
would need to do differently.

Is there something the PCI core could do better to make this easier?
Or is it just something like "the PCI core needs to access registers
after suspend_late()"?  You mention the host controller, but of course
that's not itself a PCI device, so the PCI core doesn't have much to
do with it directly.

s/register/registers/ ?

> Device link support in the clock framework enforce that the clock
> driver's resume() callback will be called before the PCIe
> driver's. But, any resume_noirq() callback will be called before all
> the registered resume() callbacks.
>
> The solution to support PCIe resume operation is to change the
> "priority" of this clock driver PM callbacks to "_noirq()".
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
>  drivers/clk/mvebu/armada-37xx-periph.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c
> index 1e18c5a875bd..bee45e43a85f 100644
> --- a/drivers/clk/mvebu/armada-37xx-periph.c
> +++ b/drivers/clk/mvebu/armada-37xx-periph.c
> @@ -715,8 +715,8 @@ static int __maybe_unused armada_3700_periph_clock_resume(struct device *dev)
>  }
>
>  static const struct dev_pm_ops armada_3700_periph_clock_pm_ops = {
> -       SET_SYSTEM_SLEEP_PM_OPS(armada_3700_periph_clock_suspend,
> -                               armada_3700_periph_clock_resume)
> +       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(armada_3700_periph_clock_suspend,
> +                                     armada_3700_periph_clock_resume)
>  };
>
>  static int armada_3700_periph_clock_probe(struct platform_device *pdev)
> --
> 2.19.1
>

Re: [PATCH v2 2/4] clk: mvebu: armada-37xx-periph: change suspend/resume time

[Miquel Raynal]

Hi Bjorn,

Thanks for the feedback.

Bjorn Helgaas <bhelgaas@google.com> wrote on Tue, 21 May 2019 17:43:05
-0500:

> From: Miquel Raynal <miquel.raynal@bootlin.com>
> Date: Tue, May 21, 2019 at 8:04 AM
> To: Michael Turquette, Stephen Boyd, Rob Herring, Mark Rutland
> Cc: <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>, Thomas
> Petazzoni, Antoine Tenart, Gregory Clement, Maxime Chevallier, Nadav
> Haklai, Bjorn Helgaas, Rafael J . Wysocki, <linux-pm@vger.kernel.org>,
> Miquel Raynal
> 
> > Armada 3700 PCIe IP relies on the PCIe clock managed by this
> > driver. For reasons related to the PCI core's organization when
> > suspending/resuming, PCI host controller drivers must reconfigure
> > their register at suspend_noirq()/resume_noirq() which happens after
> > suspend()/suspend_late() and before resume_early()/resume().
> 
> "For reasons related to the PCI core's organization" manages to
> suggest that this change wouldn't be needed if only the PCI core did
> something differently, without actually being specific about what it
> would need to do differently.
> 
> Is there something the PCI core could do better to make this easier?
> Or is it just something like "the PCI core needs to access registers
> after suspend_late()"?  You mention the host controller, but of course
> that's not itself a PCI device, so the PCI core doesn't have much to
> do with it directly.

Actually, if I understand correctly the below commit [1] and the core
[2] & [3], PCI device fixups can happen at any time, including at the
_noirq phase where, obviously, the PCI controller must be already
setup.

I don't think changing this behavior is a viable solution and I would
not see it as a "PCI core could do better" alternative.

---8<---

[1]
commit ab14d45ea58eae67c739e4ba01871cae7b6c4586
Author: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Date:   Tue Mar 17 15:55:45 2015 +0100

    PCI: mvebu: Add suspend/resume support

    Add suspend/resume support for the mvebu PCIe host driver.  Without
    this commit, the system will panic at resume time when PCIe devices
    are connected.

    Note that we have to use the ->suspend_noirq() and ->resume_noirq()
    hooks, because at resume time, the PCI fixups are done at
    ->resume_noirq() time, so the PCIe controller has to be ready at
    this point.

    Signed-off-by: Thomas Petazzoni
    <thomas.petazzoni@free-electrons.com> Signed-off-by: Bjorn Helgaas
    <bhelgaas@google.com> Acked-by: Jason Cooper <jason@lakedaemon.net>

[2] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L1181
[3] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L522

--->8---

> 
> s/register/registers/ ?

Indeed. I would like to sort out the above technical point before
sending a v3 with this typo corrected.


Thanks,
Miquèl

Re: [PATCH v2 2/4] clk: mvebu: armada-37xx-periph: change suspend/resume time

[Bjorn Helgaas]

On Mon, May 27, 2019 at 8:46 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>
> Hi Bjorn,
>
> Thanks for the feedback.
>
> Bjorn Helgaas <bhelgaas@google.com> wrote on Tue, 21 May 2019 17:43:05
> -0500:
>
> > From: Miquel Raynal <miquel.raynal@bootlin.com>
> > Date: Tue, May 21, 2019 at 8:04 AM
> > To: Michael Turquette, Stephen Boyd, Rob Herring, Mark Rutland
> > Cc: <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>, Thomas
> > Petazzoni, Antoine Tenart, Gregory Clement, Maxime Chevallier, Nadav
> > Haklai, Bjorn Helgaas, Rafael J . Wysocki, <linux-pm@vger.kernel.org>,
> > Miquel Raynal
> >
> > > Armada 3700 PCIe IP relies on the PCIe clock managed by this
> > > driver. For reasons related to the PCI core's organization when
> > > suspending/resuming, PCI host controller drivers must reconfigure
> > > their register at suspend_noirq()/resume_noirq() which happens after
> > > suspend()/suspend_late() and before resume_early()/resume().
> >
> > "For reasons related to the PCI core's organization" manages to
> > suggest that this change wouldn't be needed if only the PCI core did
> > something differently, without actually being specific about what it
> > would need to do differently.
> >
> > Is there something the PCI core could do better to make this easier?
> > Or is it just something like "the PCI core needs to access registers
> > after suspend_late()"?  You mention the host controller, but of course
> > that's not itself a PCI device, so the PCI core doesn't have much to
> > do with it directly.
>
> Actually, if I understand correctly the below commit [1] and the core
> [2] & [3], PCI device fixups can happen at any time, including at the
> _noirq phase where, obviously, the PCI controller must be already
> setup.
>
> I don't think changing this behavior is a viable solution and I would
> not see it as a "PCI core could do better" alternative.
>
> ---8<---
>
> [1]
> commit ab14d45ea58eae67c739e4ba01871cae7b6c4586
> Author: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Date:   Tue Mar 17 15:55:45 2015 +0100
>
>     PCI: mvebu: Add suspend/resume support
>
>     Add suspend/resume support for the mvebu PCIe host driver.  Without
>     this commit, the system will panic at resume time when PCIe devices
>     are connected.
>
>     Note that we have to use the ->suspend_noirq() and ->resume_noirq()
>     hooks, because at resume time, the PCI fixups are done at
>     ->resume_noirq() time, so the PCIe controller has to be ready at
>     this point.
>
>     Signed-off-by: Thomas Petazzoni
>     <thomas.petazzoni@free-electrons.com> Signed-off-by: Bjorn Helgaas
>     <bhelgaas@google.com> Acked-by: Jason Cooper <jason@lakedaemon.net>
>
> [2] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L1181
> [3] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L522
>
> --->8---
>
> >
> > s/register/registers/ ?
>
> Indeed. I would like to sort out the above technical point before
> sending a v3 with this typo corrected.

I don't have anything more to contribute here; just wanted to make
sure this wasn't working around a fixable problem in PCI.

Bjorn

Re: [PATCH v2 2/4] clk: mvebu: armada-37xx-periph: change suspend/resume time

[Miquel Raynal]

Hi Bjorn,

Bjorn Helgaas <bhelgaas@google.com> wrote on Tue, 4 Jun 2019 15:52:31
-0500:

> On Mon, May 27, 2019 at 8:46 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> >
> > Hi Bjorn,
> >
> > Thanks for the feedback.
> >
> > Bjorn Helgaas <bhelgaas@google.com> wrote on Tue, 21 May 2019 17:43:05
> > -0500:
> >  
> > > From: Miquel Raynal <miquel.raynal@bootlin.com>
> > > Date: Tue, May 21, 2019 at 8:04 AM
> > > To: Michael Turquette, Stephen Boyd, Rob Herring, Mark Rutland
> > > Cc: <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>, Thomas
> > > Petazzoni, Antoine Tenart, Gregory Clement, Maxime Chevallier, Nadav
> > > Haklai, Bjorn Helgaas, Rafael J . Wysocki, <linux-pm@vger.kernel.org>,
> > > Miquel Raynal
> > >  
> > > > Armada 3700 PCIe IP relies on the PCIe clock managed by this
> > > > driver. For reasons related to the PCI core's organization when
> > > > suspending/resuming, PCI host controller drivers must reconfigure
> > > > their register at suspend_noirq()/resume_noirq() which happens after
> > > > suspend()/suspend_late() and before resume_early()/resume().  
> > >
> > > "For reasons related to the PCI core's organization" manages to
> > > suggest that this change wouldn't be needed if only the PCI core did
> > > something differently, without actually being specific about what it
> > > would need to do differently.
> > >
> > > Is there something the PCI core could do better to make this easier?
> > > Or is it just something like "the PCI core needs to access registers
> > > after suspend_late()"?  You mention the host controller, but of course
> > > that's not itself a PCI device, so the PCI core doesn't have much to
> > > do with it directly.  
> >
> > Actually, if I understand correctly the below commit [1] and the core
> > [2] & [3], PCI device fixups can happen at any time, including at the
> > _noirq phase where, obviously, the PCI controller must be already
> > setup.
> >
> > I don't think changing this behavior is a viable solution and I would
> > not see it as a "PCI core could do better" alternative.
> >
> > ---8<---
> >
> > [1]
> > commit ab14d45ea58eae67c739e4ba01871cae7b6c4586
> > Author: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> > Date:   Tue Mar 17 15:55:45 2015 +0100
> >
> >     PCI: mvebu: Add suspend/resume support
> >
> >     Add suspend/resume support for the mvebu PCIe host driver.  Without
> >     this commit, the system will panic at resume time when PCIe devices
> >     are connected.
> >
> >     Note that we have to use the ->suspend_noirq() and ->resume_noirq()
> >     hooks, because at resume time, the PCI fixups are done at  
> >     ->resume_noirq() time, so the PCIe controller has to be ready at  
> >     this point.
> >
> >     Signed-off-by: Thomas Petazzoni
> >     <thomas.petazzoni@free-electrons.com> Signed-off-by: Bjorn Helgaas
> >     <bhelgaas@google.com> Acked-by: Jason Cooper <jason@lakedaemon.net>
> >
> > [2] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L1181
> > [3] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L522
> >  
> > --->8---  
> >  
> > >
> > > s/register/registers/ ?  
> >
> > Indeed. I would like to sort out the above technical point before
> > sending a v3 with this typo corrected.  
> 
> I don't have anything more to contribute here; just wanted to make
> sure this wasn't working around a fixable problem in PCI.

Great! Would you mind adding a A-b/R-b tag then?


Thanks,
Miquèl

Re: [PATCH v2 2/4] clk: mvebu: armada-37xx-periph: change suspend/resume time

[Bjorn Helgaas]

On Mon, Jun 17, 2019 at 7:50 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
>
> Hi Bjorn,
>
> Bjorn Helgaas <bhelgaas@google.com> wrote on Tue, 4 Jun 2019 15:52:31
> -0500:
>
> > On Mon, May 27, 2019 at 8:46 AM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> > >
> > > Hi Bjorn,
> > >
> > > Thanks for the feedback.
> > >
> > > Bjorn Helgaas <bhelgaas@google.com> wrote on Tue, 21 May 2019 17:43:05
> > > -0500:
> > >
> > > > From: Miquel Raynal <miquel.raynal@bootlin.com>
> > > > Date: Tue, May 21, 2019 at 8:04 AM
> > > > To: Michael Turquette, Stephen Boyd, Rob Herring, Mark Rutland
> > > > Cc: <linux-clk@vger.kernel.org>, <devicetree@vger.kernel.org>, Thomas
> > > > Petazzoni, Antoine Tenart, Gregory Clement, Maxime Chevallier, Nadav
> > > > Haklai, Bjorn Helgaas, Rafael J . Wysocki, <linux-pm@vger.kernel.org>,
> > > > Miquel Raynal
> > > >
> > > > > Armada 3700 PCIe IP relies on the PCIe clock managed by this
> > > > > driver. For reasons related to the PCI core's organization when
> > > > > suspending/resuming, PCI host controller drivers must reconfigure
> > > > > their register at suspend_noirq()/resume_noirq() which happens after
> > > > > suspend()/suspend_late() and before resume_early()/resume().
> > > >
> > > > "For reasons related to the PCI core's organization" manages to
> > > > suggest that this change wouldn't be needed if only the PCI core did
> > > > something differently, without actually being specific about what it
> > > > would need to do differently.
> > > >
> > > > Is there something the PCI core could do better to make this easier?
> > > > Or is it just something like "the PCI core needs to access registers
> > > > after suspend_late()"?  You mention the host controller, but of course
> > > > that's not itself a PCI device, so the PCI core doesn't have much to
> > > > do with it directly.
> > >
> > > Actually, if I understand correctly the below commit [1] and the core
> > > [2] & [3], PCI device fixups can happen at any time, including at the
> > > _noirq phase where, obviously, the PCI controller must be already
> > > setup.
> > >
> > > I don't think changing this behavior is a viable solution and I would
> > > not see it as a "PCI core could do better" alternative.
> > >
> > > ---8<---
> > >
> > > [1]
> > > commit ab14d45ea58eae67c739e4ba01871cae7b6c4586
> > > Author: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> > > Date:   Tue Mar 17 15:55:45 2015 +0100
> > >
> > >     PCI: mvebu: Add suspend/resume support
> > >
> > >     Add suspend/resume support for the mvebu PCIe host driver.  Without
> > >     this commit, the system will panic at resume time when PCIe devices
> > >     are connected.
> > >
> > >     Note that we have to use the ->suspend_noirq() and ->resume_noirq()
> > >     hooks, because at resume time, the PCI fixups are done at
> > >     ->resume_noirq() time, so the PCIe controller has to be ready at
> > >     this point.
> > >
> > >     Signed-off-by: Thomas Petazzoni
> > >     <thomas.petazzoni@free-electrons.com> Signed-off-by: Bjorn Helgaas
> > >     <bhelgaas@google.com> Acked-by: Jason Cooper <jason@lakedaemon.net>
> > >
> > > [2] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L1181
> > > [3] https://elixir.bootlin.com/linux/v5.2-rc1/source/drivers/pci/pci-driver.c#L522
> > >
> > > --->8---
> > >
> > > >
> > > > s/register/registers/ ?
> > >
> > > Indeed. I would like to sort out the above technical point before
> > > sending a v3 with this typo corrected.
> >
> > I don't have anything more to contribute here; just wanted to make
> > sure this wasn't working around a fixable problem in PCI.
>
> Great! Would you mind adding a A-b/R-b tag then?

You're only touching drivers/clk, so you don't need my ack, and I
don't really feel qualified to add a reviewed-by.  Power management
and suspend/resume is still a mystery to me :)

Bjorn