[PATCH v2 1/6] Revert "PCI: dw-rockchip: Don't wait for link since we can detect Link Up"

[PATCH v2 1/6] Revert "PCI: dw-rockchip: Don't wait for link since we can detect Link Up"

[Niklas Cassel]

This reverts commit ec9fd499b9c60a187ac8d6414c3c343c77d32e42.

While this fake hotplugging was a nice idea, it has shown that this feature
does not handle PCIe switches correctly:
pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46

During the initial scan, PCI core doesn't see the switch and since the Root
Port is not hot plug capable, the secondary bus number gets assigned as the
subordinate bus number. This means, the PCI core assumes that only one bus
will appear behind the Root Port since the Root Port is not hot plug
capable.

This works perfectly fine for PCIe endpoints connected to the Root Port,
since they don't extend the bus. However, if a PCIe switch is connected,
then there is a problem when the downstream busses starts showing up and
the PCI core doesn't extend the subordinate bus number after initial scan
during boot.

The long term plan is to migrate this driver to the pwrctrl framework,
once it adds proper support for powering up and enumerating PCIe switches.

Cc: stable@vger.kernel.org
Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index 8c1c92208802..ca808d8f7975 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -601,7 +601,6 @@ static int rockchip_pcie_configure_rc(struct platform_device *pdev,
 
 	pp = &rockchip->pci.pp;
 	pp->ops = &rockchip_pcie_host_ops;
-	pp->use_linkup_irq = true;
 
 	ret = dw_pcie_host_init(pp);
 	if (ret) {
-- 
2.52.0

Re: [PATCH v2 1/6] Revert "PCI: dw-rockchip: Don't wait for link since we can detect Link Up"

[Bjorn Helgaas]

[+cc Ilpo]

On Mon, Dec 22, 2025 at 07:42:08AM +0100, Niklas Cassel wrote:
> This reverts commit ec9fd499b9c60a187ac8d6414c3c343c77d32e42.
> 
> While this fake hotplugging was a nice idea, it has shown that this feature
> does not handle PCIe switches correctly:
> pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])

Apart from the actual problem you're fixing, it looks like some of our
bus number resource setup is a little deficient here.  The "43-41" and
"42-41" ranges are bogus and "(null)" doesn't tell us anything useful.

> pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
> pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
> pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
> pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
> pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
> pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
> pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
> pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
> pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
> pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
> pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
> pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46
> 
> During the initial scan, PCI core doesn't see the switch and since the Root
> Port is not hot plug capable, the secondary bus number gets assigned as the
> subordinate bus number. This means, the PCI core assumes that only one bus
> will appear behind the Root Port since the Root Port is not hot plug
> capable.
> 
> This works perfectly fine for PCIe endpoints connected to the Root Port,
> since they don't extend the bus. However, if a PCIe switch is connected,
> then there is a problem when the downstream busses starts showing up and
> the PCI core doesn't extend the subordinate bus number after initial scan
> during boot.

I suppose this is could also be viewed as a resource management
problem.  

Even in the normal hotplug case, we never know what a hot-added
hierarchy will look like, so we hack around it with the compiled-in
DEFAULT_HOTPLUG_BUS_SIZE and the "hpbussize=" kernel parameter.

It would be nice if we could allocate more bus numbers at hot-add (or
link-up) time as needed.  That's hard after drivers have claimed
nearby devices, but in this case there might not be anything nearby.

> The long term plan is to migrate this driver to the pwrctrl framework,
> once it adds proper support for powering up and enumerating PCIe switches.

"Proper" is hiding some important details here.  pwrctrl already
supports powering up and enumerating switches.  I think this refers to
[1], where Mani says the plan is for pwrctrl to power up everything
before the initial bus scan so we can figure out how many buses are
needed.

Bjorn

[1] https://lore.kernel.org/linux-pci/fle74skju2rorxmfdvosmeyrx3g75rysuszov5ofvde2exj4ir@3kfjyfyhczmn/

Re: [PATCH v2 1/6] Revert "PCI: dw-rockchip: Don't wait for link since we can detect Link Up"

[Niklas Cassel]

Hello Bjorn,

On Fri, Dec 26, 2025 at 04:31:59PM -0600, Bjorn Helgaas wrote:
> > The long term plan is to migrate this driver to the pwrctrl framework,
> > once it adds proper support for powering up and enumerating PCIe switches.
> 
> "Proper" is hiding some important details here.  pwrctrl already
> supports powering up and enumerating switches.  I think this refers to
> [1], where Mani says the plan is for pwrctrl to power up everything
> before the initial bus scan so we can figure out how many buses are
> needed.
> 
> [1] https://lore.kernel.org/linux-pci/fle74skju2rorxmfdvosmeyrx3g75rysuszov5ofvde2exj4ir@3kfjyfyhczmn/

Correct.

This series has already been merged to the pci/controller/dwc branch
(although for some reason this branch is not merged to pci/next yet),
and I can see that Mani have rephrased the commit messages to be more
specific and to avoid the word proper.

Please tell me if there is some futher action needed from my part.


Kind regards,
Niklas

[PATCH v2 2/6] Revert "PCI: dw-rockchip: Enumerate endpoints based on dll_link_up IRQ"

[Niklas Cassel]

This reverts commit 0e0b45ab5d770a748487ba0ae8f77d1fb0f0de3e.

While this fake hotplugging was a nice idea, it has shown that this feature
does not handle PCIe switches correctly:
pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46

During the initial scan, PCI core doesn't see the switch and since the Root
Port is not hot plug capable, the secondary bus number gets assigned as the
subordinate bus number. This means, the PCI core assumes that only one bus
will appear behind the Root Port since the Root Port is not hot plug
capable.

This works perfectly fine for PCIe endpoints connected to the Root Port,
since they don't extend the bus. However, if a PCIe switch is connected,
then there is a problem when the downstream busses starts showing up and
the PCI core doesn't extend the subordinate bus number after initial scan
during boot.

The long term plan is to migrate this driver to the pwrctrl framework,
once it adds proper support for powering up and enumerating PCIe switches.

Cc: stable@vger.kernel.org
Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 59 +------------------
 1 file changed, 3 insertions(+), 56 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index ca808d8f7975..352f513ebf03 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -508,34 +508,6 @@ static const struct dw_pcie_ops dw_pcie_ops = {
 	.get_ltssm = rockchip_pcie_get_ltssm,
 };
 
-static irqreturn_t rockchip_pcie_rc_sys_irq_thread(int irq, void *arg)
-{
-	struct rockchip_pcie *rockchip = arg;
-	struct dw_pcie *pci = &rockchip->pci;
-	struct dw_pcie_rp *pp = &pci->pp;
-	struct device *dev = pci->dev;
-	u32 reg;
-
-	reg = rockchip_pcie_readl_apb(rockchip, PCIE_CLIENT_INTR_STATUS_MISC);
-	rockchip_pcie_writel_apb(rockchip, reg, PCIE_CLIENT_INTR_STATUS_MISC);
-
-	dev_dbg(dev, "PCIE_CLIENT_INTR_STATUS_MISC: %#x\n", reg);
-	dev_dbg(dev, "LTSSM_STATUS: %#x\n", rockchip_pcie_get_ltssm_reg(rockchip));
-
-	if (reg & PCIE_RDLH_LINK_UP_CHGED) {
-		if (rockchip_pcie_link_up(pci)) {
-			msleep(PCIE_RESET_CONFIG_WAIT_MS);
-			dev_dbg(dev, "Received Link up event. Starting enumeration!\n");
-			/* Rescan the bus to enumerate endpoint devices */
-			pci_lock_rescan_remove();
-			pci_rescan_bus(pp->bridge->bus);
-			pci_unlock_rescan_remove();
-		}
-	}
-
-	return IRQ_HANDLED;
-}
-
 static irqreturn_t rockchip_pcie_ep_sys_irq_thread(int irq, void *arg)
 {
 	struct rockchip_pcie *rockchip = arg;
@@ -568,29 +540,14 @@ static irqreturn_t rockchip_pcie_ep_sys_irq_thread(int irq, void *arg)
 	return IRQ_HANDLED;
 }
 
-static int rockchip_pcie_configure_rc(struct platform_device *pdev,
-				      struct rockchip_pcie *rockchip)
+static int rockchip_pcie_configure_rc(struct rockchip_pcie *rockchip)
 {
-	struct device *dev = &pdev->dev;
 	struct dw_pcie_rp *pp;
-	int irq, ret;
 	u32 val;
 
 	if (!IS_ENABLED(CONFIG_PCIE_ROCKCHIP_DW_HOST))
 		return -ENODEV;
 
-	irq = platform_get_irq_byname(pdev, "sys");
-	if (irq < 0)
-		return irq;
-
-	ret = devm_request_threaded_irq(dev, irq, NULL,
-					rockchip_pcie_rc_sys_irq_thread,
-					IRQF_ONESHOT, "pcie-sys-rc", rockchip);
-	if (ret) {
-		dev_err(dev, "failed to request PCIe sys IRQ\n");
-		return ret;
-	}
-
 	/* LTSSM enable control mode */
 	val = FIELD_PREP_WM16(PCIE_LTSSM_ENABLE_ENHANCE, 1);
 	rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_HOT_RESET_CTRL);
@@ -602,17 +559,7 @@ static int rockchip_pcie_configure_rc(struct platform_device *pdev,
 	pp = &rockchip->pci.pp;
 	pp->ops = &rockchip_pcie_host_ops;
 
-	ret = dw_pcie_host_init(pp);
-	if (ret) {
-		dev_err(dev, "failed to initialize host\n");
-		return ret;
-	}
-
-	/* unmask DLL up/down indicator */
-	val = FIELD_PREP_WM16(PCIE_RDLH_LINK_UP_CHGED, 0);
-	rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_INTR_MASK_MISC);
-
-	return ret;
+	return dw_pcie_host_init(pp);
 }
 
 static int rockchip_pcie_configure_ep(struct platform_device *pdev,
@@ -731,7 +678,7 @@ static int rockchip_pcie_probe(struct platform_device *pdev)
 
 	switch (data->mode) {
 	case DW_PCIE_RC_TYPE:
-		ret = rockchip_pcie_configure_rc(pdev, rockchip);
+		ret = rockchip_pcie_configure_rc(rockchip);
 		if (ret)
 			goto deinit_clk;
 		break;
-- 
2.52.0

[PATCH v2 3/6] Revert "PCI: qcom: Don't wait for link if we can detect Link Up"

[Niklas Cassel]

This reverts commit 36971d6c5a9a134c15760ae9fd13c6d5f9a36abb.

While this fake hotplugging was a nice idea, it has shown that this feature
does not handle PCIe switches correctly:
pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46

During the initial scan, PCI core doesn't see the switch and since the Root
Port is not hot plug capable, the secondary bus number gets assigned as the
subordinate bus number. This means, the PCI core assumes that only one bus
will appear behind the Root Port since the Root Port is not hot plug
capable.

This works perfectly fine for PCIe endpoints connected to the Root Port,
since they don't extend the bus. However, if a PCIe switch is connected,
then there is a problem when the downstream busses starts showing up and
the PCI core doesn't extend the subordinate bus number after initial scan
during boot.

The long term plan is to migrate this driver to the pwrctrl framework,
once it adds proper support for powering up and enumerating PCIe switches.

Cc: stable@vger.kernel.org
Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 60373fe1362f..e87ec6779d44 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -1958,10 +1958,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcie);
 
-	irq = platform_get_irq_byname_optional(pdev, "global");
-	if (irq > 0)
-		pp->use_linkup_irq = true;
-
 	ret = dw_pcie_host_init(pp);
 	if (ret) {
 		dev_err(dev, "cannot initialize host\n");
@@ -1975,6 +1971,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 		goto err_host_deinit;
 	}
 
+	irq = platform_get_irq_byname_optional(pdev, "global");
 	if (irq > 0) {
 		ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 						qcom_pcie_global_irq_thread,
-- 
2.52.0

[PATCH v2 4/6] Revert "PCI: qcom: Enable MSI interrupts together with Link up if 'Global IRQ' is supported"

[Niklas Cassel]

This reverts commit ba4a2e2317b9faeca9193ed6d3193ddc3cf2aba3.

While this fake hotplugging was a nice idea, it has shown that this feature
does not handle PCIe switches correctly:
pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46

During the initial scan, PCI core doesn't see the switch and since the Root
Port is not hot plug capable, the secondary bus number gets assigned as the
subordinate bus number. This means, the PCI core assumes that only one bus
will appear behind the Root Port since the Root Port is not hot plug
capable.

This works perfectly fine for PCIe endpoints connected to the Root Port,
since they don't extend the bus. However, if a PCIe switch is connected,
then there is a problem when the downstream busses starts showing up and
the PCI core doesn't extend the subordinate bus number after initial scan
during boot.

The long term plan is to migrate this driver to the pwrctrl framework,
once it adds proper support for powering up and enumerating PCIe switches.

Cc: stable@vger.kernel.org
Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index e87ec6779d44..c5fcb87972e9 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -136,7 +136,6 @@
 
 /* PARF_INT_ALL_{STATUS/CLEAR/MASK} register fields */
 #define PARF_INT_ALL_LINK_UP			BIT(13)
-#define PARF_INT_MSI_DEV_0_7			GENMASK(30, 23)
 
 /* PARF_NO_SNOOP_OVERRIDE register fields */
 #define WR_NO_SNOOP_OVERRIDE_EN			BIT(1)
@@ -1982,8 +1981,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 			goto err_host_deinit;
 		}
 
-		writel_relaxed(PARF_INT_ALL_LINK_UP | PARF_INT_MSI_DEV_0_7,
-			       pcie->parf + PARF_INT_ALL_MASK);
+		writel_relaxed(PARF_INT_ALL_LINK_UP, pcie->parf + PARF_INT_ALL_MASK);
 	}
 
 	qcom_pcie_icc_opp_update(pcie);
-- 
2.52.0

Re: [PATCH v2 4/6] Revert "PCI: qcom: Enable MSI interrupts together with Link up if 'Global IRQ' is supported"

[Krishna Chaitanya Chundru]

On 12/22/2025 12:12 PM, Niklas Cassel wrote:
> This reverts commit ba4a2e2317b9faeca9193ed6d3193ddc3cf2aba3.
>
> While this fake hotplugging was a nice idea, it has shown that this feature
> does not handle PCIe switches correctly:
> pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
> pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
> pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
> pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
> pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
> pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
> pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
> pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
> pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
> pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
> pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
> pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46
>
> During the initial scan, PCI core doesn't see the switch and since the Root
> Port is not hot plug capable, the secondary bus number gets assigned as the
> subordinate bus number. This means, the PCI core assumes that only one bus
> will appear behind the Root Port since the Root Port is not hot plug
> capable.
>
> This works perfectly fine for PCIe endpoints connected to the Root Port,
> since they don't extend the bus. However, if a PCIe switch is connected,
> then there is a problem when the downstream busses starts showing up and
> the PCI core doesn't extend the subordinate bus number after initial scan
> during boot.
>
> The long term plan is to migrate this driver to the pwrctrl framework,
> once it adds proper support for powering up and enumerating PCIe switches.
>
> Cc: stable@vger.kernel.org
> Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
> Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
> Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
> ---
>   drivers/pci/controller/dwc/pcie-qcom.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index e87ec6779d44..c5fcb87972e9 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -136,7 +136,6 @@
>   
>   /* PARF_INT_ALL_{STATUS/CLEAR/MASK} register fields */
>   #define PARF_INT_ALL_LINK_UP			BIT(13)
> -#define PARF_INT_MSI_DEV_0_7			GENMASK(30, 23)
>   
>   /* PARF_NO_SNOOP_OVERRIDE register fields */
>   #define WR_NO_SNOOP_OVERRIDE_EN			BIT(1)
> @@ -1982,8 +1981,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>   			goto err_host_deinit;
>   		}
>   
> -		writel_relaxed(PARF_INT_ALL_LINK_UP | PARF_INT_MSI_DEV_0_7,
> -			       pcie->parf + PARF_INT_ALL_MASK);
MSI's needs to be enabled irrespective of this series as part of global 
IRQ otherwise
MSI's will not be triggered in few platforms.

Mani, exclude this patch while applying.

- Krishna Chaitanya
> +		writel_relaxed(PARF_INT_ALL_LINK_UP, pcie->parf + PARF_INT_ALL_MASK);
>   	}
>   
>   	qcom_pcie_icc_opp_update(pcie);

Re: [PATCH v2 4/6] Revert "PCI: qcom: Enable MSI interrupts together with Link up if 'Global IRQ' is supported"

[Niklas Cassel]

On Mon, Dec 22, 2025 at 12:18:32PM +0530, Krishna Chaitanya Chundru wrote:
> > @@ -1982,8 +1981,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
> >   			goto err_host_deinit;
> >   		}
> > -		writel_relaxed(PARF_INT_ALL_LINK_UP | PARF_INT_MSI_DEV_0_7,
> > -			       pcie->parf + PARF_INT_ALL_MASK);
> MSI's needs to be enabled irrespective of this series as part of global IRQ
> otherwise
> MSI's will not be triggered in few platforms.
> 
> Mani, exclude this patch while applying.

From the commit message of the reverted patch:

  The MSI bits in PARF_INT_ALL_MASK register are enabled
  by default in the hardware, but commit 4581403f6792 ("PCI: qcom: Enumerate
  endpoints based on Link up event in 'global_irq' interrupt") disabled them
  and enabled only the Link up interrupt.


Thus, applying this patch should be safe, or at least bring back the
original behavior as it was before the Link Up IRQ patches got applied.

But if you prefer to enable the MSI bits explicitly, in order to not
rely on HW defaults, that should also be fine.


Kind regards,
Niklas

Re: [PATCH v2 4/6] Revert "PCI: qcom: Enable MSI interrupts together with Link up if 'Global IRQ' is supported"

[Manivannan Sadhasivam]

+ Qiang

On Mon, Dec 22, 2025 at 08:00:57AM +0100, Niklas Cassel wrote:
> On Mon, Dec 22, 2025 at 12:18:32PM +0530, Krishna Chaitanya Chundru wrote:
> > > @@ -1982,8 +1981,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
> > >   			goto err_host_deinit;
> > >   		}
> > > -		writel_relaxed(PARF_INT_ALL_LINK_UP | PARF_INT_MSI_DEV_0_7,
> > > -			       pcie->parf + PARF_INT_ALL_MASK);
> > MSI's needs to be enabled irrespective of this series as part of global IRQ
> > otherwise
> > MSI's will not be triggered in few platforms.
> > 
> > Mani, exclude this patch while applying.
> 
> From the commit message of the reverted patch:
> 
>   The MSI bits in PARF_INT_ALL_MASK register are enabled
>   by default in the hardware, but commit 4581403f6792 ("PCI: qcom: Enumerate
>   endpoints based on Link up event in 'global_irq' interrupt") disabled them
>   and enabled only the Link up interrupt.
> 
> 
> Thus, applying this patch should be safe, or at least bring back the
> original behavior as it was before the Link Up IRQ patches got applied.
> 

Yes!

> But if you prefer to enable the MSI bits explicitly, in order to not
> rely on HW defaults, that should also be fine.
> 

I believe Qiang reported internally that we need to explicitly enable
PARF_INT_MSI_DEV_0_7 for all platforms as the hardware default is not always
correct. So that should come as a separate patch.

- Mani

-- 
மணிவண்ணன் சதாசிவம்

[PATCH v2 5/6] Revert "PCI: qcom: Enumerate endpoints based on Link up event in 'global_irq' interrupt"

[Niklas Cassel]

This reverts commit 4581403f67929d02c197cb187c4e1e811c9e762a.

While this fake hotplugging was a nice idea, it has shown that this feature
does not handle PCIe switches correctly:
pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46

During the initial scan, PCI core doesn't see the switch and since the Root
Port is not hot plug capable, the secondary bus number gets assigned as the
subordinate bus number. This means, the PCI core assumes that only one bus
will appear behind the Root Port since the Root Port is not hot plug
capable.

This works perfectly fine for PCIe endpoints connected to the Root Port,
since they don't extend the bus. However, if a PCIe switch is connected,
then there is a problem when the downstream busses starts showing up and
the PCI core doesn't extend the subordinate bus number after initial scan
during boot.

The long term plan is to migrate this driver to the pwrctrl framework,
once it adds proper support for powering up and enumerating PCIe switches.

Cc: stable@vger.kernel.org
Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 58 +-------------------------
 1 file changed, 1 insertion(+), 57 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index c5fcb87972e9..13e6c334e10d 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -55,9 +55,6 @@
 #define PARF_AXI_MSTR_WR_ADDR_HALT_V2		0x1a8
 #define PARF_Q2A_FLUSH				0x1ac
 #define PARF_LTSSM				0x1b0
-#define PARF_INT_ALL_STATUS			0x224
-#define PARF_INT_ALL_CLEAR			0x228
-#define PARF_INT_ALL_MASK			0x22c
 #define PARF_SID_OFFSET				0x234
 #define PARF_BDF_TRANSLATE_CFG			0x24c
 #define PARF_DBI_BASE_ADDR_V2			0x350
@@ -134,9 +131,6 @@
 /* PARF_LTSSM register fields */
 #define LTSSM_EN				BIT(8)
 
-/* PARF_INT_ALL_{STATUS/CLEAR/MASK} register fields */
-#define PARF_INT_ALL_LINK_UP			BIT(13)
-
 /* PARF_NO_SNOOP_OVERRIDE register fields */
 #define WR_NO_SNOOP_OVERRIDE_EN			BIT(1)
 #define RD_NO_SNOOP_OVERRIDE_EN			BIT(3)
@@ -1635,32 +1629,6 @@ static void qcom_pcie_init_debugfs(struct qcom_pcie *pcie)
 				    qcom_pcie_link_transition_count);
 }
 
-static irqreturn_t qcom_pcie_global_irq_thread(int irq, void *data)
-{
-	struct qcom_pcie *pcie = data;
-	struct dw_pcie_rp *pp = &pcie->pci->pp;
-	struct device *dev = pcie->pci->dev;
-	u32 status = readl_relaxed(pcie->parf + PARF_INT_ALL_STATUS);
-
-	writel_relaxed(status, pcie->parf + PARF_INT_ALL_CLEAR);
-
-	if (FIELD_GET(PARF_INT_ALL_LINK_UP, status)) {
-		msleep(PCIE_RESET_CONFIG_WAIT_MS);
-		dev_dbg(dev, "Received Link up event. Starting enumeration!\n");
-		/* Rescan the bus to enumerate endpoint devices */
-		pci_lock_rescan_remove();
-		pci_rescan_bus(pp->bridge->bus);
-		pci_unlock_rescan_remove();
-
-		qcom_pcie_icc_opp_update(pcie);
-	} else {
-		dev_WARN_ONCE(dev, 1, "Received unknown event. INT_STATUS: 0x%08x\n",
-			      status);
-	}
-
-	return IRQ_HANDLED;
-}
-
 static void qcom_pci_free_msi(void *ptr)
 {
 	struct dw_pcie_rp *pp = (struct dw_pcie_rp *)ptr;
@@ -1805,8 +1773,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 	struct dw_pcie_rp *pp;
 	struct resource *res;
 	struct dw_pcie *pci;
-	int ret, irq;
-	char *name;
+	int ret;
 
 	pcie_cfg = of_device_get_match_data(dev);
 	if (!pcie_cfg) {
@@ -1963,27 +1930,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 		goto err_phy_exit;
 	}
 
-	name = devm_kasprintf(dev, GFP_KERNEL, "qcom_pcie_global_irq%d",
-			      pci_domain_nr(pp->bridge->bus));
-	if (!name) {
-		ret = -ENOMEM;
-		goto err_host_deinit;
-	}
-
-	irq = platform_get_irq_byname_optional(pdev, "global");
-	if (irq > 0) {
-		ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
-						qcom_pcie_global_irq_thread,
-						IRQF_ONESHOT, name, pcie);
-		if (ret) {
-			dev_err_probe(&pdev->dev, ret,
-				      "Failed to request Global IRQ\n");
-			goto err_host_deinit;
-		}
-
-		writel_relaxed(PARF_INT_ALL_LINK_UP, pcie->parf + PARF_INT_ALL_MASK);
-	}
-
 	qcom_pcie_icc_opp_update(pcie);
 
 	if (pcie->mhi)
@@ -1991,8 +1937,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 
 	return 0;
 
-err_host_deinit:
-	dw_pcie_host_deinit(pp);
 err_phy_exit:
 	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
 		phy_exit(port->phy);
-- 
2.52.0

Re: [PATCH v2 5/6] Revert "PCI: qcom: Enumerate endpoints based on Link up event in 'global_irq' interrupt"

[Krishna Chaitanya Chundru]

On 12/22/2025 12:12 PM, Niklas Cassel wrote:
> This reverts commit 4581403f67929d02c197cb187c4e1e811c9e762a.
>
> While this fake hotplugging was a nice idea, it has shown that this feature
> does not handle PCIe switches correctly:
> pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
> pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
> pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
> pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
> pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
> pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
> pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
> pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
> pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
> pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
> pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
> pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
> pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46
>
> During the initial scan, PCI core doesn't see the switch and since the Root
> Port is not hot plug capable, the secondary bus number gets assigned as the
> subordinate bus number. This means, the PCI core assumes that only one bus
> will appear behind the Root Port since the Root Port is not hot plug
> capable.
>
> This works perfectly fine for PCIe endpoints connected to the Root Port,
> since they don't extend the bus. However, if a PCIe switch is connected,
> then there is a problem when the downstream busses starts showing up and
> the PCI core doesn't extend the subordinate bus number after initial scan
> during boot.
>
> The long term plan is to migrate this driver to the pwrctrl framework,
> once it adds proper support for powering up and enumerating PCIe switches.
>
> Cc: stable@vger.kernel.org
> Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
> Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
> Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
> Signed-off-by: Niklas Cassel <cassel@kernel.org>
Removing patch 3/6 should be sufficient, don't remove global IRQ patch, 
this will be helpful
when endpoint is connected at later point of time.

- Krishna Chaitanya.
> ---
>   drivers/pci/controller/dwc/pcie-qcom.c | 58 +-------------------------
>   1 file changed, 1 insertion(+), 57 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index c5fcb87972e9..13e6c334e10d 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -55,9 +55,6 @@
>   #define PARF_AXI_MSTR_WR_ADDR_HALT_V2		0x1a8
>   #define PARF_Q2A_FLUSH				0x1ac
>   #define PARF_LTSSM				0x1b0
> -#define PARF_INT_ALL_STATUS			0x224
> -#define PARF_INT_ALL_CLEAR			0x228
> -#define PARF_INT_ALL_MASK			0x22c
>   #define PARF_SID_OFFSET				0x234
>   #define PARF_BDF_TRANSLATE_CFG			0x24c
>   #define PARF_DBI_BASE_ADDR_V2			0x350
> @@ -134,9 +131,6 @@
>   /* PARF_LTSSM register fields */
>   #define LTSSM_EN				BIT(8)
>   
> -/* PARF_INT_ALL_{STATUS/CLEAR/MASK} register fields */
> -#define PARF_INT_ALL_LINK_UP			BIT(13)
> -
>   /* PARF_NO_SNOOP_OVERRIDE register fields */
>   #define WR_NO_SNOOP_OVERRIDE_EN			BIT(1)
>   #define RD_NO_SNOOP_OVERRIDE_EN			BIT(3)
> @@ -1635,32 +1629,6 @@ static void qcom_pcie_init_debugfs(struct qcom_pcie *pcie)
>   				    qcom_pcie_link_transition_count);
>   }
>   
> -static irqreturn_t qcom_pcie_global_irq_thread(int irq, void *data)
> -{
> -	struct qcom_pcie *pcie = data;
> -	struct dw_pcie_rp *pp = &pcie->pci->pp;
> -	struct device *dev = pcie->pci->dev;
> -	u32 status = readl_relaxed(pcie->parf + PARF_INT_ALL_STATUS);
> -
> -	writel_relaxed(status, pcie->parf + PARF_INT_ALL_CLEAR);
> -
> -	if (FIELD_GET(PARF_INT_ALL_LINK_UP, status)) {
> -		msleep(PCIE_RESET_CONFIG_WAIT_MS);
> -		dev_dbg(dev, "Received Link up event. Starting enumeration!\n");
> -		/* Rescan the bus to enumerate endpoint devices */
> -		pci_lock_rescan_remove();
> -		pci_rescan_bus(pp->bridge->bus);
> -		pci_unlock_rescan_remove();
> -
> -		qcom_pcie_icc_opp_update(pcie);
> -	} else {
> -		dev_WARN_ONCE(dev, 1, "Received unknown event. INT_STATUS: 0x%08x\n",
> -			      status);
> -	}
> -
> -	return IRQ_HANDLED;
> -}
> -
>   static void qcom_pci_free_msi(void *ptr)
>   {
>   	struct dw_pcie_rp *pp = (struct dw_pcie_rp *)ptr;
> @@ -1805,8 +1773,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>   	struct dw_pcie_rp *pp;
>   	struct resource *res;
>   	struct dw_pcie *pci;
> -	int ret, irq;
> -	char *name;
> +	int ret;
>   
>   	pcie_cfg = of_device_get_match_data(dev);
>   	if (!pcie_cfg) {
> @@ -1963,27 +1930,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>   		goto err_phy_exit;
>   	}
>   
> -	name = devm_kasprintf(dev, GFP_KERNEL, "qcom_pcie_global_irq%d",
> -			      pci_domain_nr(pp->bridge->bus));
> -	if (!name) {
> -		ret = -ENOMEM;
> -		goto err_host_deinit;
> -	}
> -
> -	irq = platform_get_irq_byname_optional(pdev, "global");
> -	if (irq > 0) {
> -		ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> -						qcom_pcie_global_irq_thread,
> -						IRQF_ONESHOT, name, pcie);
> -		if (ret) {
> -			dev_err_probe(&pdev->dev, ret,
> -				      "Failed to request Global IRQ\n");
> -			goto err_host_deinit;
> -		}
> -
> -		writel_relaxed(PARF_INT_ALL_LINK_UP, pcie->parf + PARF_INT_ALL_MASK);
> -	}
> -
>   	qcom_pcie_icc_opp_update(pcie);
>   
>   	if (pcie->mhi)
> @@ -1991,8 +1937,6 @@ static int qcom_pcie_probe(struct platform_device *pdev)
>   
>   	return 0;
>   
> -err_host_deinit:
> -	dw_pcie_host_deinit(pp);
>   err_phy_exit:
>   	list_for_each_entry_safe(port, tmp, &pcie->ports, list) {
>   		phy_exit(port->phy);

Re: [PATCH v2 5/6] Revert "PCI: qcom: Enumerate endpoints based on Link up event in 'global_irq' interrupt"

[Niklas Cassel]

Hello Krishna,

On Mon, Dec 22, 2025 at 12:21:16PM +0530, Krishna Chaitanya Chundru wrote:
> Removing patch 3/6 should be sufficient, don't remove global IRQ patch, this
> will be helpful
> when endpoint is connected at later point of time.

Please see Mani's reply here:
https://lore.kernel.org/linux-pci/fle74skju2rorxmfdvosmeyrx3g75rysuszov5ofvde2exj4ir@3kfjyfyhczmn/

"And neither the controller driver."

Sounds to me like he still wants this patch
(which removes the support from the controller driver).


Kind regards,
Niklas

Re: [PATCH v2 5/6] Revert "PCI: qcom: Enumerate endpoints based on Link up event in 'global_irq' interrupt"

[Manivannan Sadhasivam]

On Mon, Dec 22, 2025 at 08:14:32AM +0100, Niklas Cassel wrote:
> Hello Krishna,
> 
> On Mon, Dec 22, 2025 at 12:21:16PM +0530, Krishna Chaitanya Chundru wrote:
> > Removing patch 3/6 should be sufficient, don't remove global IRQ patch, this
> > will be helpful
> > when endpoint is connected at later point of time.
> 
> Please see Mani's reply here:
> https://lore.kernel.org/linux-pci/fle74skju2rorxmfdvosmeyrx3g75rysuszov5ofvde2exj4ir@3kfjyfyhczmn/
> 
> "And neither the controller driver."
> 
> Sounds to me like he still wants this patch
> (which removes the support from the controller driver).
> 

Yes, allowing hotplug for a non-hotplug Root Port is a bad idea. Too bad that I
proposed it in the first place... Let's revert for all platforms to avoid
setting bad precedence.

- Mani

-- 
மணிவண்ணன் சதாசிவம்

[PATCH v2 6/6] Revert "PCI: dwc: Don't wait for link up if driver can detect Link Up event"

[Niklas Cassel]

This reverts commit 8d3bf19f1b585a3cc0027f508b64c33484db8d0d.

While this fake hotplugging was a nice idea, it has shown that this feature
does not handle PCIe switches correctly:
pci_bus 0004:43: busn_res: can not insert [bus 43-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:43: busn_res: [bus 43-41] end is updated to 43
pci_bus 0004:43: busn_res: can not insert [bus 43] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:00.0: devices behind bridge are unusable because [bus 43] cannot be assigned for them
pci_bus 0004:44: busn_res: can not insert [bus 44-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:44: busn_res: [bus 44-41] end is updated to 44
pci_bus 0004:44: busn_res: can not insert [bus 44] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:02.0: devices behind bridge are unusable because [bus 44] cannot be assigned for them
pci_bus 0004:45: busn_res: can not insert [bus 45-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:45: busn_res: [bus 45-41] end is updated to 45
pci_bus 0004:45: busn_res: can not insert [bus 45] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:06.0: devices behind bridge are unusable because [bus 45] cannot be assigned for them
pci_bus 0004:46: busn_res: can not insert [bus 46-41] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci_bus 0004:46: busn_res: [bus 46-41] end is updated to 46
pci_bus 0004:46: busn_res: can not insert [bus 46] under [bus 42-41] (conflicts with (null) [bus 42-41])
pci 0004:42:0e.0: devices behind bridge are unusable because [bus 46] cannot be assigned for them
pci_bus 0004:42: busn_res: [bus 42-41] end is updated to 46
pci_bus 0004:42: busn_res: can not insert [bus 42-46] under [bus 41] (conflicts with (null) [bus 41])
pci 0004:41:00.0: devices behind bridge are unusable because [bus 42-46] cannot be assigned for them
pcieport 0004:40:00.0: bridge has subordinate 41 but max busn 46

During the initial scan, PCI core doesn't see the switch and since the Root
Port is not hot plug capable, the secondary bus number gets assigned as the
subordinate bus number. This means, the PCI core assumes that only one bus
will appear behind the Root Port since the Root Port is not hot plug
capable.

This works perfectly fine for PCIe endpoints connected to the Root Port,
since they don't extend the bus. However, if a PCIe switch is connected,
then there is a problem when the downstream busses starts showing up and
the PCI core doesn't extend the subordinate bus number after initial scan
during boot.

The long term plan is to migrate this driver to the pwrctrl framework,
once it adds proper support for powering up and enumerating PCIe switches.

Cc: stable@vger.kernel.org
Suggested-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 10 ++--------
 drivers/pci/controller/dwc/pcie-designware.h      |  1 -
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 8c41b90a1db1..06c02fcc76c8 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -665,14 +665,8 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
 			goto err_remove_edma;
 	}
 
-	/*
-	 * Note: Skip the link up delay only when a Link Up IRQ is present.
-	 * If there is no Link Up IRQ, we should not bypass the delay
-	 * because that would require users to manually rescan for devices.
-	 */
-	if (!pp->use_linkup_irq)
-		/* Ignore errors, the link may come up later */
-		dw_pcie_wait_for_link(pci);
+	/* Ignore errors, the link may come up later */
+	dw_pcie_wait_for_link(pci);
 
 	ret = pci_host_probe(bridge);
 	if (ret)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index fc9cf8ce8629..a3a3f6e89a81 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -438,7 +438,6 @@ struct dw_pcie_rp {
 	bool			use_atu_msg;
 	int			msg_atu_index;
 	struct resource		*msg_res;
-	bool			use_linkup_irq;
 	struct pci_eq_presets	presets;
 	struct pci_config_window *cfg;
 	bool			ecam_enabled;
-- 
2.52.0