[PATCH RESEND v2] PCI: imx6: Enable ASPM L1 only iff CLKREQ# is supported

[PATCH RESEND v2] PCI: imx6: Enable ASPM L1 only iff CLKREQ# is supported

[Michal Gorlas]

Since commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM
states for devicetree platforms"), ASPM states are force enabled
on all devicetree platforms. This causes PCI devices on some i.MX SoCs
(for e.g. i.MX 8M Plus Kontron SMARC eval carrier) to enter L1 even
though CLKREQ# is not supported (and consequently supports-clkreq is
not set in pcie controller node of their DT), which causes the device to
never wake up from L1.

Hence, disable L1 capability in the LNKCAP register if supports-clkreq
is not set in the DT explicitly. For devices that set
IMX_PCIE_FLAG_BROKEN_SUSPEND, disable L1 on resume as well, as these
skip imx_pcie_host_init().

Note, the logic here is very similar to 613f3255a35a, only difference
is that leaving L0s enabled does not cause issues (at least
I never encountered them myself when testing on the device) as its
not dependent on CLKREQ# being physically there.
Since there is already a way of specifying its presence in the DT,
the driver should be aware and disable L1.

Fixes: f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for devicetree platforms")
Signed-off-by: Michal Gorlas <michal.gorlas@9elements.com>
Tested-by: Richard Zhu <hongxing.zhu@nxp.com>
Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
---
Changes in v2:
- disable L1 unconditionally on resume for platforms advertising
IMX_PCIE_FLAG_BROKEN_SUSPEND (Sashiko)
- typos in the commit message
- Link to v1: https://patch.msgid.link/20260719-l1-conditional-imx-v1-1-a55a57915c68@9elements.com
---
 drivers/pci/controller/dwc/pci-imx6.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 98e1db751132..1fdcbcd2422e 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1318,6 +1318,22 @@ static void imx_pcie_assert_perst(struct imx_pcie *imx_pcie, bool assert)
 	}
 }
 
+static void imx_pcie_disable_l1(struct dw_pcie *pci)
+{
+	u32 val;
+	u8 offset;
+
+	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+
+	dw_pcie_dbi_ro_wr_en(pci);
+
+	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
+	val &= ~PCI_EXP_LNKCAP_ASPM_L1;
+	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, val);
+
+	dw_pcie_dbi_ro_wr_dis(pci);
+}
+
 static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -1442,6 +1458,9 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 
 	imx_setup_phy_mpll(imx_pcie);
 
+	if (!imx_pcie->supports_clkreq)
+		imx_pcie_disable_l1(pci);
+
 	return 0;
 
 err_phy_off:
@@ -1748,6 +1767,7 @@ static int imx_pcie_resume_noirq(struct device *dev)
 			return ret;
 		imx_pcie_deassert_core_reset(imx_pcie);
 		imx_pcie_assert_perst(imx_pcie, false);
+		imx_pcie_disable_l1(imx_pcie->pci);
 
 		/*
 		 * Using PCIE_TEST_PD seems to disable MSI and powers down the

---
base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
change-id: 20260713-l1-conditional-imx-c2bfd20ae085

Best regards,
-- 
Michal Gorlas <michal.gorlas@9elements.com>

Re: [PATCH RESEND v2] PCI: imx6: Enable ASPM L1 only iff CLKREQ# is supported

[sashiko-bot]

> Since commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM
> states for devicetree platforms"), ASPM states are force enabled
> on all devicetree platforms. This causes PCI devices on some i.MX SoCs
> (for e.g. i.MX 8M Plus Kontron SMARC eval carrier) to enter L1 even
> though CLKREQ# is not supported (and consequently supports-clkreq is
> not set in pcie controller node of their DT), which causes the device to
> never wake up from L1.
> 
> Hence, disable L1 capability in the LNKCAP register if supports-clkreq
> is not set in the DT explicitly. For devices that set
> IMX_PCIE_FLAG_BROKEN_SUSPEND, disable L1 on resume as well, as these
> skip imx_pcie_host_init().
> 
> Note, the logic here is very similar to 613f3255a35a, only difference
> is that leaving L0s enabled does not cause issues (at least
> I never encountered them myself when testing on the device) as its
> not dependent on CLKREQ# being physically there.
> Since there is already a way of specifying its presence in the DT,
> the driver should be aware and disable L1.
> 
> Fixes: f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for devicetree platforms")
> Signed-off-by: Michal Gorlas <michal.gorlas@9elements.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260827-l1-conditional-imx-v2-1-40b324aa2a94@9elements.com?part=1

Re: [PATCH RESEND v2] PCI: imx6: Enable ASPM L1 only iff CLKREQ# is supported

[Frank Li]

On Thu, Aug 27, 2026 at 06:51:00PM +0200, Michal Gorlas wrote:
> Since commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM
> states for devicetree platforms"), ASPM states are force enabled
> on all devicetree platforms. This causes PCI devices on some i.MX SoCs
> (for e.g. i.MX 8M Plus Kontron SMARC eval carrier) to enter L1 even
> though CLKREQ# is not supported (and consequently supports-clkreq is
> not set in pcie controller node of their DT), which causes the device to
> never wake up from L1.
>
> Hence, disable L1 capability in the LNKCAP register if supports-clkreq
> is not set in the DT explicitly. For devices that set
> IMX_PCIE_FLAG_BROKEN_SUSPEND, disable L1 on resume as well, as these
> skip imx_pcie_host_init().
>
> Note, the logic here is very similar to 613f3255a35a, only difference
> is that leaving L0s enabled does not cause issues (at least
> I never encountered them myself when testing on the device) as its
> not dependent on CLKREQ# being physically there.
> Since there is already a way of specifying its presence in the DT,
> the driver should be aware and disable L1.
>
> Fixes: f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for devicetree platforms")
> Signed-off-by: Michal Gorlas <michal.gorlas@9elements.com>
> Tested-by: Richard Zhu <hongxing.zhu@nxp.com>
> Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
> Changes in v2:
> - disable L1 unconditionally on resume for platforms advertising
> IMX_PCIE_FLAG_BROKEN_SUSPEND (Sashiko)
> - typos in the commit message
> - Link to v1: https://patch.msgid.link/20260719-l1-conditional-imx-v1-1-a55a57915c68@9elements.com
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 98e1db751132..1fdcbcd2422e 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1318,6 +1318,22 @@ static void imx_pcie_assert_perst(struct imx_pcie *imx_pcie, bool assert)
>  	}
>  }
>
> +static void imx_pcie_disable_l1(struct dw_pcie *pci)
> +{
> +	u32 val;
> +	u8 offset;
> +
> +	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> +
> +	dw_pcie_dbi_ro_wr_en(pci);
> +
> +	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> +	val &= ~PCI_EXP_LNKCAP_ASPM_L1;
> +	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, val);
> +
> +	dw_pcie_dbi_ro_wr_dis(pci);
> +}
> +
>  static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>  {
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> @@ -1442,6 +1458,9 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>
>  	imx_setup_phy_mpll(imx_pcie);
>
> +	if (!imx_pcie->supports_clkreq)
> +		imx_pcie_disable_l1(pci);
> +
>  	return 0;
>
>  err_phy_off:
> @@ -1748,6 +1767,7 @@ static int imx_pcie_resume_noirq(struct device *dev)
>  			return ret;
>  		imx_pcie_deassert_core_reset(imx_pcie);
>  		imx_pcie_assert_perst(imx_pcie, false);
> +		imx_pcie_disable_l1(imx_pcie->pci);

Does l1 disable permanent after resume? should it be

	if (!imx_pcie->supports_clkreq)
		mx_pcie_disable_l1(imx_pcie->pci);

Frank

>
>  		/*
>  		 * Using PCIE_TEST_PD seems to disable MSI and powers down the
>
> ---
> base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
> change-id: 20260713-l1-conditional-imx-c2bfd20ae085
>
> Best regards,
> --
> Michal Gorlas <michal.gorlas@9elements.com>
>

Re: [PATCH RESEND v2] PCI: imx6: Enable ASPM L1 only iff CLKREQ# is supported

[Michal Gorlas]

On Thu Aug 27, 2026 at 7:10 PM CEST, Frank Li wrote:
> On Thu, Aug 27, 2026 at 06:51:00PM +0200, Michal Gorlas wrote:
>> Since commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM
>> states for devicetree platforms"), ASPM states are force enabled
>> on all devicetree platforms. This causes PCI devices on some i.MX SoCs
>> (for e.g. i.MX 8M Plus Kontron SMARC eval carrier) to enter L1 even
>> though CLKREQ# is not supported (and consequently supports-clkreq is
>> not set in pcie controller node of their DT), which causes the device to
>> never wake up from L1.
>>
>> Hence, disable L1 capability in the LNKCAP register if supports-clkreq
>> is not set in the DT explicitly. For devices that set
>> IMX_PCIE_FLAG_BROKEN_SUSPEND, disable L1 on resume as well, as these
>> skip imx_pcie_host_init().
>>
>> Note, the logic here is very similar to 613f3255a35a, only difference
>> is that leaving L0s enabled does not cause issues (at least
>> I never encountered them myself when testing on the device) as its
>> not dependent on CLKREQ# being physically there.
>> Since there is already a way of specifying its presence in the DT,
>> the driver should be aware and disable L1.
>>
>> Fixes: f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for devicetree platforms")
>> Signed-off-by: Michal Gorlas <michal.gorlas@9elements.com>
>> Tested-by: Richard Zhu <hongxing.zhu@nxp.com>
>> Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
>> ---
>> Changes in v2:
>> - disable L1 unconditionally on resume for platforms advertising
>> IMX_PCIE_FLAG_BROKEN_SUSPEND (Sashiko)
>> - typos in the commit message
>> - Link to v1: https://patch.msgid.link/20260719-l1-conditional-imx-v1-1-a55a57915c68@9elements.com
>> ---
>>  drivers/pci/controller/dwc/pci-imx6.c | 20 ++++++++++++++++++++
>>  1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
>> index 98e1db751132..1fdcbcd2422e 100644
>> --- a/drivers/pci/controller/dwc/pci-imx6.c
>> +++ b/drivers/pci/controller/dwc/pci-imx6.c
>> @@ -1318,6 +1318,22 @@ static void imx_pcie_assert_perst(struct imx_pcie *imx_pcie, bool assert)
>>  	}
>>  }
>>
>> +static void imx_pcie_disable_l1(struct dw_pcie *pci)
>> +{
>> +	u32 val;
>> +	u8 offset;
>> +
>> +	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
>> +
>> +	dw_pcie_dbi_ro_wr_en(pci);
>> +
>> +	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
>> +	val &= ~PCI_EXP_LNKCAP_ASPM_L1;
>> +	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, val);
>> +
>> +	dw_pcie_dbi_ro_wr_dis(pci);
>> +}
>> +
>>  static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>>  {
>>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> @@ -1442,6 +1458,9 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>>
>>  	imx_setup_phy_mpll(imx_pcie);
>>
>> +	if (!imx_pcie->supports_clkreq)
>> +		imx_pcie_disable_l1(pci);
>> +
>>  	return 0;
>>
>>  err_phy_off:
>> @@ -1748,6 +1767,7 @@ static int imx_pcie_resume_noirq(struct device *dev)
>>  			return ret;
>>  		imx_pcie_deassert_core_reset(imx_pcie);
>>  		imx_pcie_assert_perst(imx_pcie, false);
>> +		imx_pcie_disable_l1(imx_pcie->pci);
>
> Does l1 disable permanent after resume? should it be
>
> 	if (!imx_pcie->supports_clkreq)
> 		mx_pcie_disable_l1(imx_pcie->pci);

It would be unnecessary, the imx_pcie_disable_l1() there is already
guarded by IMX_PCIE_FLAG_BROKEN_SUSPEND, so we know that only iMX6Q
ends up there on resume. And none of iMX6Q DT's sets supports-clkreq.

Best,
Michal
>
> Frank
>
>>
>>  		/*
>>  		 * Using PCIE_TEST_PD seems to disable MSI and powers down the
>>
>> ---
>> base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
>> change-id: 20260713-l1-conditional-imx-c2bfd20ae085
>>
>> Best regards,
>> --
>> Michal Gorlas <michal.gorlas@9elements.com>
>>

Re: [PATCH RESEND v2] PCI: imx6: Enable ASPM L1 only iff CLKREQ# is supported

[Frank Li]

On Thu, Aug 27, 2026 at 08:29:09PM +0200, Michal Gorlas wrote:
> On Thu Aug 27, 2026 at 7:10 PM CEST, Frank Li wrote:
> > On Thu, Aug 27, 2026 at 06:51:00PM +0200, Michal Gorlas wrote:
> >> Since commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM
> >> states for devicetree platforms"), ASPM states are force enabled
> >> on all devicetree platforms. This causes PCI devices on some i.MX SoCs
> >> (for e.g. i.MX 8M Plus Kontron SMARC eval carrier) to enter L1 even
> >> though CLKREQ# is not supported (and consequently supports-clkreq is
> >> not set in pcie controller node of their DT), which causes the device to
> >> never wake up from L1.
> >>
> >> Hence, disable L1 capability in the LNKCAP register if supports-clkreq
> >> is not set in the DT explicitly. For devices that set
> >> IMX_PCIE_FLAG_BROKEN_SUSPEND, disable L1 on resume as well, as these
> >> skip imx_pcie_host_init().
> >>
> >> Note, the logic here is very similar to 613f3255a35a, only difference
> >> is that leaving L0s enabled does not cause issues (at least
> >> I never encountered them myself when testing on the device) as its
> >> not dependent on CLKREQ# being physically there.
> >> Since there is already a way of specifying its presence in the DT,
> >> the driver should be aware and disable L1.
> >>
> >> Fixes: f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM states for devicetree platforms")
> >> Signed-off-by: Michal Gorlas <michal.gorlas@9elements.com>
> >> Tested-by: Richard Zhu <hongxing.zhu@nxp.com>
> >> Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
> >> ---
> >> Changes in v2:
> >> - disable L1 unconditionally on resume for platforms advertising
> >> IMX_PCIE_FLAG_BROKEN_SUSPEND (Sashiko)
> >> - typos in the commit message
> >> - Link to v1: https://patch.msgid.link/20260719-l1-conditional-imx-v1-1-a55a57915c68@9elements.com
> >> ---
> >>  drivers/pci/controller/dwc/pci-imx6.c | 20 ++++++++++++++++++++
> >>  1 file changed, 20 insertions(+)
> >>
> >> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> >> index 98e1db751132..1fdcbcd2422e 100644
> >> --- a/drivers/pci/controller/dwc/pci-imx6.c
> >> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> >> @@ -1318,6 +1318,22 @@ static void imx_pcie_assert_perst(struct imx_pcie *imx_pcie, bool assert)
> >>  	}
> >>  }
> >>
> >> +static void imx_pcie_disable_l1(struct dw_pcie *pci)
> >> +{
> >> +	u32 val;
> >> +	u8 offset;
> >> +
> >> +	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
> >> +
> >> +	dw_pcie_dbi_ro_wr_en(pci);
> >> +
> >> +	val = dw_pcie_readl_dbi(pci, offset + PCI_EXP_LNKCAP);
> >> +	val &= ~PCI_EXP_LNKCAP_ASPM_L1;
> >> +	dw_pcie_writel_dbi(pci, offset + PCI_EXP_LNKCAP, val);
> >> +
> >> +	dw_pcie_dbi_ro_wr_dis(pci);
> >> +}
> >> +
> >>  static int imx_pcie_host_init(struct dw_pcie_rp *pp)
> >>  {
> >>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> >> @@ -1442,6 +1458,9 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
> >>
> >>  	imx_setup_phy_mpll(imx_pcie);
> >>
> >> +	if (!imx_pcie->supports_clkreq)
> >> +		imx_pcie_disable_l1(pci);
> >> +
> >>  	return 0;
> >>
> >>  err_phy_off:
> >> @@ -1748,6 +1767,7 @@ static int imx_pcie_resume_noirq(struct device *dev)
> >>  			return ret;
> >>  		imx_pcie_deassert_core_reset(imx_pcie);
> >>  		imx_pcie_assert_perst(imx_pcie, false);
> >> +		imx_pcie_disable_l1(imx_pcie->pci);
> >
> > Does l1 disable permanent after resume? should it be
> >
> > 	if (!imx_pcie->supports_clkreq)
> > 		mx_pcie_disable_l1(imx_pcie->pci);
>
> It would be unnecessary, the imx_pcie_disable_l1() there is already
> guarded by IMX_PCIE_FLAG_BROKEN_SUSPEND, so we know that only iMX6Q
> ends up there on resume. And none of iMX6Q DT's sets supports-clkreq.

Okay,

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>
> Best,
> Michal
> >
> > Frank
> >
> >>
> >>  		/*
> >>  		 * Using PCIE_TEST_PD seems to disable MSI and powers down the
> >>
> >> ---
> >> base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
> >> change-id: 20260713-l1-conditional-imx-c2bfd20ae085
> >>
> >> Best regards,
> >> --
> >> Michal Gorlas <michal.gorlas@9elements.com>
> >>
>