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[PATCH v3 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions

Richard Zhu posted 2 patches 3 months, 3 weeks ago
There is a newer version of this series
[PATCH v3 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions
Posted by Richard Zhu 3 months, 3 weeks ago 
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.

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()")
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
---
 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
Re: [PATCH v3 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions
Posted by Manivannan Sadhasivam 3 months, 2 weeks ago 
On Mon, Jun 16, 2025 at 04:57:41PM +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();
> 

What about other i.MX chipsets like 6Q and its cousins? Wouldn't this change
affect them since they treat 'apps_reset' differently?

- Mani

> 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.
> 
> 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()")
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> ---
>  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
> 

-- 
மணிவண்ணன் சதாசிவம்
Re: [PATCH v3 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions
Posted by Tim Harvey 3 months, 2 weeks ago 
On Mon, Jun 23, 2025 at 4:42 AM Manivannan Sadhasivam <mani@kernel.org> wrote:
>
> On Mon, Jun 16, 2025 at 04:57:41PM +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();
> >
>
> What about other i.MX chipsets like 6Q and its cousins? Wouldn't this change
> affect them since they treat 'apps_reset' differently?
>
> - Mani

Hi Main,

This patch effectively brings back the behavior prior to commit
ef61c7d8d032 ("PCI: imx6: Deassert apps_reset in
imx_pcie_deassert_core_reset()") which caused the original
regressions.

To ease your concerns I've tested this patch on top of v6.16-rc3 with
the following IMX6 boards I have here with and without a PCI device
attached:
imx6q-gw51xx - no switch
imx6q-gw54xx - switch

I only have imx6qdl/imx8mm/imx8mp boards to test with.

From what I can tell it doesn't look like the original patch that
added the 'symmetric' apps_reset de-assert was necessarily well
tested. It started out being added because as far as I can tell it
'looked' like the right thing to do [1]. You requested changes to the
commit log for wording [2],[3] but I'm unclear that anyone tested
this.

Best Regards,

Tim
[1] https://patchwork.kernel.org/project/linux-pci/patch/1727148464-14341-6-git-send-email-hongxing.zhu@nxp.com/
[2] https://patchwork.kernel.org/project/linux-pci/patch/1728981213-8771-6-git-send-email-hongxing.zhu@nxp.com/
[3] https://patchwork.kernel.org/project/linux-pci/patch/20241101070610.1267391-6-hongxing.zhu@nxp.com/
Re: [PATCH v3 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions
Posted by Tim Harvey 3 months, 3 weeks ago 
On Mon, Jun 16, 2025 at 1:59 AM Richard Zhu <hongxing.zhu@nxp.com> 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.
>
> Fix fail to enumerate reliably PI7C9X2G608GP (hotplug) at i.MX8MM, which
> reported By Tim.
>
> 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()")
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> Reviewed-by: Frank Li <Frank.Li@nxp.com>
> ---
>  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
>

Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mp-venice-gw74xx
(i.MX8MP + hotplug capable switch)

Best Regards,

Tim

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