[PATCH v5 0/2] PCI: rockchip-host: Make the PERST# inactive delay configurable

[PATCH v5 0/2] PCI: rockchip-host: Make the PERST# inactive delay configurable

[Enrique Hernández Bello]

rockchip_pcie_host_init_port() waits T_PVPERL, 100 ms, before releasing
PERST#. The line has been asserted since the GPIO was acquired early in
probe, so that wait is also the reset pulse width.

Endpoints do not agree on what they want there. Some need longer to settle;
a JMB585 behind a ROCK Pi 4C stops answering configuration reads if the
pulse is stretched that far. The measurements are in patch 2.

So, as Shawn suggested, take the delay from the device tree instead of
changing it for everyone. Patch 1 documents rockchip,perst-inactive-ms and
rockchip,s2r-perst-inactive-ms, named after the properties the Rockchip
vendor driver already carries for the dwc-based controllers; patch 2 reads
them. The defaults leave current behaviour untouched, so there is no Fixes:
tag and nothing to backport.

There is no DT patch for my board in this series. Its JMB585 sits on a Radxa
Penta SATA HAT, which is not described upstream, so the property belongs in
an overlay.

Tested on that board with the series backported to 6.18.58, the kernel
Talos Linux ships; only the context of the #include hunk differs. One
kernel build, two images that differ only in the overlay: with
rockchip,perst-inactive-ms = <0>, the JMB585 enumerated on 4 boots out of
4; without the property, all 3 boots hit the same SError in
rockchip_pcie_rd_conf() during probe that the board hits without the
series.

Igor, since the defaults are unchanged, a Helios64 with no DT change should
behave exactly like plain mainline. If you want to exercise the property
as well:

	&pcie0 {
		rockchip,perst-inactive-ms = <10>;
	};

A wait of 0 to 15 ms enumerated 17 times out of 17 on my board, but your
slot supply is a GPIO-switched regulator where mine is always on, so I
would not take my numbers as a guide for yours.

v4: https://lore.kernel.org/all/20261028014116.2432425-1-ehbello@gmail.com/
v3 (discussion with Shawn): https://lore.kernel.org/all/20261028005603.2399220-1-ehbello@gmail.com/

Changes in v5:
- Take the delay from the device tree, as suggested by Shawn Lin, instead of
  shortening the wait automatically when the slot supplies were found
  already enabled.
- Drop struct rockchip_pcie::supplies_pre_enabled and
  rockchip_pcie_supplies_enabled() altogether. That also retires the hole
  Shawn found in them: devm_regulator_get() returns a dummy regulator for an
  absent rail and the dummy reports itself enabled, so the old test was
  unconditionally true on a board describing none of its supplies, on resume
  included.
- Keep the 100 us floor from v4, now for any value a board asks for.
- Split into a bindings patch and a driver patch.

Changes in v4:
- Hold PERST# for T_PERST-CLK in the shortened path. Old power does not
  imply an old REFCLK: init_port() runs phy_init()/phy_power_on() on every
  probe and resume, so the PLL relocks microseconds before the release.
  Measured 72-75 us by ftrace, i.e. a real violation of the 100 us minimum.

Enrique Hernández Bello (2):
  dt-bindings: PCI: rockchip,rk3399-pcie: Add PERST# inactive delay
    properties
  PCI: rockchip-host: Make the PERST# inactive delay configurable

 .../bindings/pci/rockchip,rk3399-pcie.yaml    | 15 +++++++++++
 drivers/pci/controller/pcie-rockchip-host.c   | 26 ++++++++++++++++---
 drivers/pci/controller/pcie-rockchip.h        |  2 ++
 3 files changed, 39 insertions(+), 4 deletions(-)

-- 
2.56.0

[PATCH v5 1/2] dt-bindings: PCI: rockchip,rk3399-pcie: Add PERST# inactive delay properties

[Enrique Hernández Bello]

The driver holds PERST# asserted for T_PVPERL (100 ms) before releasing it.
Endpoints disagree about what they want there: some need longer than the
default to settle, while others stop answering configuration reads when the
reset pulse is stretched that far, because PERST# stays asserted for the
whole wait.

Describe two properties so a board can state what its endpoint needs, named
after the ones the Rockchip vendor driver already uses for the dwc-based
controllers:

  rockchip,perst-inactive-ms      - the delay used at probe
  rockchip,s2r-perst-inactive-ms  - the delay used when resuming

Both are optional and the defaults preserve the current behaviour.

Signed-off-by: Enrique Hernández Bello <ehbello@gmail.com>
---
 .../bindings/pci/rockchip,rk3399-pcie.yaml        | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
index 720a5f9..7ac915c 100644
--- a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
@@ -40,6 +40,21 @@ properties:
     maxItems: 1
     description: pre-reset GPIO
 
+  rockchip,perst-inactive-ms:
+    default: 100
+    description:
+      Time PERST# is held asserted before it is released, which is also the
+      width of the reset pulse. The default meets T_PVPERL for a slot that
+      is powered at the moment PERST# is asserted. Some endpoints need more
+      settling time than that, while others stop responding when the pulse
+      is that long. A value of 0 selects the 100 us minimum the PCI Express
+      CEM specification sets for the pulse.
+
+  rockchip,s2r-perst-inactive-ms:
+    description:
+      The same time, applied when resuming from system suspend. Defaults to
+      the value of rockchip,perst-inactive-ms.
+
   vpcie12v-supply:
     description: The 12v regulator to use for PCIe.
 
-- 
2.56.0

Re: [PATCH v5 1/2] dt-bindings: PCI: rockchip,rk3399-pcie: Add PERST# inactive delay properties

[Krzysztof Kozlowski]

On Wed, Nov 04, 2026 at 09:58:46PM +0000, Enrique Hernández Bello wrote:
> The driver holds PERST# asserted for T_PVPERL (100 ms) before releasing it.
> Endpoints disagree about what they want there: some need longer than the
> default to settle, while others stop answering configuration reads when the
> reset pulse is stretched that far, because PERST# stays asserted for the
> whole wait.
> 
> Describe two properties so a board can state what its endpoint needs, named
> after the ones the Rockchip vendor driver already uses for the dwc-based
> controllers:

Vendor driver does not matter, it is antipattern. Do not mention it here
as reason to do such change.

> 
>   rockchip,perst-inactive-ms      - the delay used at probe
>   rockchip,s2r-perst-inactive-ms  - the delay used when resuming

No need to repeat the diff.

> 
> Both are optional and the defaults preserve the current behaviour.
> 
> Signed-off-by: Enrique Hernández Bello <ehbello@gmail.com>
> ---
>  .../bindings/pci/rockchip,rk3399-pcie.yaml        | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
> index 720a5f9..7ac915c 100644
> --- a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
> +++ b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie.yaml
> @@ -40,6 +40,21 @@ properties:
>      maxItems: 1
>      description: pre-reset GPIO
>  
> +  rockchip,perst-inactive-ms:
> +    default: 100
> +    description:
> +      Time PERST# is held asserted before it is released, which is also the
> +      width of the reset pulse. The default meets T_PVPERL for a slot that
> +      is powered at the moment PERST# is asserted. Some endpoints need more
> +      settling time than that, while others stop responding when the pulse
> +      is that long. A value of 0 selects the 100 us minimum the PCI Express

us or ms?

> +      CEM specification sets for the pulse.

What is the nature of this timing? 100 ms is a lot. Are you sure you are
not describing RC delay (we have bindings for that already)

Best regards,
Krzysztof

Re: [PATCH v5 1/2] dt-bindings: PCI: rockchip,rk3399-pcie: Add PERST# inactive delay properties

[Enrique Hernández Bello]

On Thu, Nov 05, 2026, Krzysztof Kozlowski wrote:
> Vendor driver does not matter, it is antipattern. Do not mention it here
> as reason to do such change.
>
> No need to repeat the diff.

Understood, both go in the next version.

> us or ms?

ms. The 0 case is badly worded: the driver never holds PERST# for less
than 100 us, whatever the value, and 0 just ends up at that floor. I will
describe the floor instead of giving 0 a meaning of its own.

> What is the nature of this timing? 100 ms is a lot. Are you sure you are
> not describing RC delay (we have bindings for that already)

The 100 ms is not something the board needs. It is the driver's current
wait, T_PVPERL from the CEM spec, applied on every board. Because PERST#
is already asserted when that wait starts, it is also the width of the
reset pulse.

On my board (ROCK Pi 4C) the slot supply is regulator-always-on, so power
has been stable for seconds before probe and there is nothing left to
settle. The problem goes the other way: the JMB585 behind it stops
answering configuration reads when it is held in reset that long. A wait
of 0 to 15 ms enumerated 17 times out of 17, 20 ms once out of 3, and
100 ms never in 5. So the board needs a shorter value, not a longer one.
I do not know why this endpoint behaves this way.

Which binding did you have in mind for the RC delay? If an existing one
fits, I would rather use it.

I also plan to drop rockchip,s2r-perst-inactive-ms, since it describes
an OS power state rather than the hardware.

Thanks,
Enrique

[PATCH v5 2/2] PCI: rockchip-host: Make the PERST# inactive delay configurable

[Enrique Hernández Bello]

rockchip_pcie_host_init_port() waits T_PVPERL, 100 ms, before releasing
PERST#. The GPIO is acquired with GPIOD_OUT_LOW early in probe, so PERST#
is already asserted when that wait starts, and the wait therefore sets the
reset pulse width as well.

That suits a board which powers the slot at the moment it asserts PERST#,
but endpoints do not agree on what they want. On a ROCK Pi 4C carrying a
JMB585 SATA controller, a pulse that long stops the endpoint answering
configuration reads at all. Measured on that board with a single kernel and
two module parameters, one sleeping before the GPIO is acquired and one in
place of the wait, timing the pulse with a ktime delta across the two
gpiod_set_value() calls:

  pre (ms)  post (ms)  pulse      trials  enumerated
  0         0          1-11 ms    5       5
  0         10         ~18 ms     3       3
  0         15         24-47 ms   4       4
  0         20         ~28 ms     3       1
  0         100        ~108 ms    4       0
  200       0          6-11 ms    5       5
  200       100        ~108 ms    1       0

Delaying the assertion changes nothing, while widening the pulse decides
everything. The slot supply on this board is regulator-always-on, so power
had been valid for seconds in every row above, the failing ones included.

Rather than change the delay for every board, read it from the device tree,
reusing the property names the Rockchip vendor driver already carries for
the dwc-based controllers in pcie-dw-rockchip.c. The default is unchanged,
so a board that describes nothing behaves exactly as before. Whatever the
board asks for, PERST# stays asserted for at least the 100 us minimum the
specification sets, which covers T_PERST and T_PERST-CLK.

Suggested-by: Shawn Lin <shawn.lin@rock-chips.com>
Link: https://lore.kernel.org/all/95aeecc0-2794-4cc6-a635-5c042afc1405@rock-chips.com/
Signed-off-by: Enrique Hernández Bello <ehbello@gmail.com>
---
 drivers/pci/controller/pcie-rockchip-host.c | 26 +++++++++++++++++----
 drivers/pci/controller/pcie-rockchip.h      |  2 ++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
index 5b071bd..5f78cd6 100644
--- a/drivers/pci/controller/pcie-rockchip-host.c
+++ b/drivers/pci/controller/pcie-rockchip-host.c
@@ -24,6 +24,7 @@
 #include <linux/of_pci.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
+#include <linux/property.h>
 #include <linux/regulator/consumer.h>
 
 #include "../pci.h"
@@ -280,8 +281,10 @@ static void rockchip_pcie_set_power_limit(struct rockchip_pcie *rockchip)
 /**
  * rockchip_pcie_host_init_port - Initialize hardware
  * @rockchip: PCIe port information
+ * @perst_inactive_ms: how long to hold PERST# asserted before releasing it
  */
-static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
+static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip,
+					u32 perst_inactive_ms)
 {
 	struct device *dev = rockchip->dev;
 	int err, i = MAX_LANE_NUM;
@@ -315,7 +318,12 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
 	rockchip_pcie_write(rockchip, PCIE_CLIENT_LINK_TRAIN_ENABLE,
 			    PCIE_CLIENT_CONFIG);
 
-	msleep(PCIE_T_PVPERL_MS);
+	/*
+	 * PERST# has been asserted since the GPIO was acquired, so this wait
+	 * is also the reset pulse width. Never go below the specification
+	 * minimum, which covers both T_PERST and T_PERST-CLK, each 100 us.
+	 */
+	fsleep(max(perst_inactive_ms * USEC_PER_MSEC, PCIE_T_PERST_CLK_US));
 	gpiod_set_value_cansleep(rockchip->perst_gpio, 1);
 
 	msleep(PCIE_RESET_CONFIG_WAIT_MS);
@@ -587,6 +595,14 @@ static int rockchip_pcie_parse_host_dt(struct rockchip_pcie *rockchip)
 	if (IS_ERR(rockchip->vpcie0v9))
 		return PTR_ERR(rockchip->vpcie0v9);
 
+	if (device_property_read_u32(dev, "rockchip,perst-inactive-ms",
+				     &rockchip->perst_inactive_ms))
+		rockchip->perst_inactive_ms = PCIE_T_PVPERL_MS;
+
+	if (device_property_read_u32(dev, "rockchip,s2r-perst-inactive-ms",
+				     &rockchip->s2r_perst_inactive_ms))
+		rockchip->s2r_perst_inactive_ms = rockchip->perst_inactive_ms;
+
 	return 0;
 }
 
@@ -881,7 +897,8 @@ static int rockchip_pcie_resume_noirq(struct device *dev)
 	if (err)
 		goto err_disable_0v9;
 
-	err = rockchip_pcie_host_init_port(rockchip);
+	err = rockchip_pcie_host_init_port(rockchip,
+					   rockchip->s2r_perst_inactive_ms);
 	if (err)
 		goto err_pcie_resume;
 
@@ -938,7 +955,8 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 		goto err_set_vpcie;
 	}
 
-	err = rockchip_pcie_host_init_port(rockchip);
+	err = rockchip_pcie_host_init_port(rockchip,
+					   rockchip->perst_inactive_ms);
 	if (err)
 		goto err_vpcie;
 
diff --git a/drivers/pci/controller/pcie-rockchip.h b/drivers/pci/controller/pcie-rockchip.h
index b5da156..c773f74 100644
--- a/drivers/pci/controller/pcie-rockchip.h
+++ b/drivers/pci/controller/pcie-rockchip.h
@@ -315,6 +315,8 @@ struct rockchip_pcie {
 	struct	regulator *vpcie1v8; /* 1.8V power supply */
 	struct	regulator *vpcie0v9; /* 0.9V power supply */
 	struct	gpio_desc *perst_gpio;
+	u32	perst_inactive_ms;
+	u32	s2r_perst_inactive_ms;
 	u32	lanes;
 	u8      lanes_map;
 	int	link_gen;
-- 
2.56.0

Re: [PATCH v5 0/2] PCI: rockchip-host: Make the PERST# inactive delay configurable

[Igor Velkov]

Tested on Helios64 (JMB585 behind a GPIO-switched slot supply) and
ROCK Pi 4A (empty slot and a WD SN770 NVMe), 7.3.1 with the series
backported, one s2idle cycle per boot:

  Helios64, no property:          resume 20/20, abort in rockchip_pcie_rd_conf() at probe on 1 of 21 boots
  Helios64, <10> probe and s2r:   resume 20/20, the same abort on 1 of 21 boots
  ROCK Pi 4A, empty slot, none/<10>:  10/10, 10/10
  ROCK Pi 4A, SN770, none/<10>:       10/10, 10/10, NVMe readable after each resume

The default behaves as before, and 10 ms changes nothing here; the
slow JMB585 link on Helios64 shows up at the same rate with either
pulse width.

Tested-by: Igor Velkov <iav@iav.lv>