[PATCH v4 0/2] PCI: imx6: Refine apps_reset and EP link behavior

[PATCH v4 0/2] PCI: imx6: Refine apps_reset and EP link behavior

[Richard Zhu]

apps_reset is LTSSM_EN on i.MX7, i.MX8MQ, i.MX8MM and i.MX8MP platforms.
Since the assertion/de-assertion of apps_reset(LTSSM_EN bit) had been
wrappered in imx_pcie_ltssm_enable() and imx_pcie_ltssm_disable();

Remove apps_reset toggle in imx_pcie_assert_core_reset() and
imx_pcie_deassert_core_reset() functions. Use imx_pcie_ltssm_enable()
and imx_pcie_ltssm_disable() to configure apps_reset directly.

Fix fail[1] to enumerate reliably PI7C9X2G608GP (hotplug) at i.MX8MM,
which reported By Tim.

Main changes in v4:
- Update commit message and add Tested-by tag in the first patch, and
  add Fixes tag into the second one.
v3: https://patchwork.kernel.org/project/linux-pci/cover/20250616085742.2684742-1-hongxing.zhu@nxp.com/

Main changes in v3:
- Correct the email address of Mani and Krzysztof Wilczyński.
- Add "Reviewed-by: Frank Li <Frank.Li@nxp.com>" tag, and rebase to v6.16-rc2
v2: https://patchwork.kernel.org/project/linux-pci/cover/20250612022747.1206053-1-hongxing.zhu@nxp.com/

Main changes in v2:
- Respin "PCI: imx6: Align EP link start behavior with" patch.
- Add the apps_reset refine patch into this patch-set.
v1: https://patchwork.kernel.org/project/linux-pci/patch/20250606075729.3855815-1-hongxing.zhu@nxp.com/

[1]https://lore.kernel.org/all/CAJ+vNU3ohR2YKTwC4xoYrc1z-neDoH2TTZcMHDy+poj9=jSy+w@mail.gmail.com/

[PATCH v4 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset
[PATCH v4 2/2] PCI: imx6: Align EP link start behavior with

drivers/pci/controller/dwc/pci-imx6.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

[PATCH v4 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions

[Richard Zhu]

apps_reset is LTSSM_EN on i.MX7, i.MX8MQ, i.MX8MM and i.MX8MP platforms.
Since the assertion/de-assertion of apps_reset(LTSSM_EN bit) had been
wrappered in imx_pcie_ltssm_enable() and imx_pcie_ltssm_disable();

Remove apps_reset toggle in imx_pcie_assert_core_reset() and
imx_pcie_deassert_core_reset() functions. Use imx_pcie_ltssm_enable()
and imx_pcie_ltssm_disable() to configure apps_reset directly.

Fix fail to enumerate reliably PI7C9X2G608GP (hotplug) at i.MX8MM, which
reported By Tim.

Only i.MX7D, i.MX8MQ, i.MX8MM, and i.MX8MP have the apps_reset. With
this change, the assertion/deassertion of LTSSM_EN bit are unified into
imx_pcie_ltssm_enable() and imx_pcie_ltssm_disable() functions, and
aligned with other i.MX platforms.

Reported-by: Tim Harvey <tharvey@gateworks.com>
Closes: https://lore.kernel.org/all/CAJ+vNU3ohR2YKTwC4xoYrc1z-neDoH2TTZcMHDy+poj9=jSy+w@mail.gmail.com/
Fixes: ef61c7d8d032 ("PCI: imx6: Deassert apps_reset in imx_pcie_deassert_core_reset()")
Cc: stable@vger.kernel.org
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mp-venice-gw74xx (i.MX8MP + hotplug capable switch)
---
 drivers/pci/controller/dwc/pci-imx6.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 9754cc6e09b9..f5f2ac638f4b 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -860,7 +860,6 @@ static int imx95_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
 static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie)
 {
 	reset_control_assert(imx_pcie->pciephy_reset);
-	reset_control_assert(imx_pcie->apps_reset);
 
 	if (imx_pcie->drvdata->core_reset)
 		imx_pcie->drvdata->core_reset(imx_pcie, true);
@@ -872,7 +871,6 @@ static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie)
 static int imx_pcie_deassert_core_reset(struct imx_pcie *imx_pcie)
 {
 	reset_control_deassert(imx_pcie->pciephy_reset);
-	reset_control_deassert(imx_pcie->apps_reset);
 
 	if (imx_pcie->drvdata->core_reset)
 		imx_pcie->drvdata->core_reset(imx_pcie, false);
@@ -1247,6 +1245,9 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 		}
 	}
 
+	/* Make sure that PCIe LTSSM is cleared */
+	imx_pcie_ltssm_disable(dev);
+
 	ret = imx_pcie_deassert_core_reset(imx_pcie);
 	if (ret < 0) {
 		dev_err(dev, "pcie deassert core reset failed: %d\n", ret);
-- 
2.37.1

[PATCH v4 2/2] PCI: imx6: Align EP link start behavior with documentation

[Richard Zhu]

According to PCI/endpoint/pci-endpoint-cfs.rst, the endpoint (EP) should
only link up after `echo 1 > start` is executed.

To match the documented behavior, do not start the link automatically
when adding the EP controller.

Fixes: 75c2f26da03f ("PCI: imx6: Add i.MX PCIe EP mode support")
Cc: stable@vger.kernel.org
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index f5f2ac638f4b..fda03512944d 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1468,9 +1468,6 @@ static int imx_add_pcie_ep(struct imx_pcie *imx_pcie,
 
 	pci_epc_init_notify(ep->epc);
 
-	/* Start LTSSM. */
-	imx_pcie_ltssm_enable(dev);
-
 	return 0;
 }
 
-- 
2.37.1

Re: [PATCH v4 0/2] PCI: imx6: Refine apps_reset and EP link behavior

[Manivannan Sadhasivam]

On Wed, 09 Jul 2025 11:37:20 +0800, Richard Zhu wrote:
> apps_reset is LTSSM_EN on i.MX7, i.MX8MQ, i.MX8MM and i.MX8MP platforms.
> Since the assertion/de-assertion of apps_reset(LTSSM_EN bit) had been
> wrappered in imx_pcie_ltssm_enable() and imx_pcie_ltssm_disable();
> 
> Remove apps_reset toggle in imx_pcie_assert_core_reset() and
> imx_pcie_deassert_core_reset() functions. Use imx_pcie_ltssm_enable()
> and imx_pcie_ltssm_disable() to configure apps_reset directly.
> 
> [...]

Applied, thanks!

[1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions
      commit: 315b747ae6b07ffabb27ed8ca584e6e6df8050a5
[2/2] PCI: imx6: Align EP link start behavior with documentation
      commit: a43b68bc510aa61a5b7618c79784dbc83074e504

Best regards,
-- 
Manivannan Sadhasivam <mani@kernel.org>