[PATCH] PCI: spacemit: Ignore link partner PERST on K1

[PATCH] PCI: spacemit: Ignore link partner PERST on K1

[Encrow Thorne]

The K1 PCIe controller and PHY are affected by the PERST signal from
the link partner during initialization. With some devices connected,
this can prevent host initialization from progressing and cause the
system to hang while probing the PCIe controller.

Set PCIE_IGNORE_PERSTN before accessing the DBI registers. When set,
this bit makes both the PCIe controller and PHY ignore the PERST
signal from the link partner.

This allows host initialization to complete without being affected by
the link partner's PERST state.

Signed-off-by: Encrow Thorne <encrow.thorne@linux.spacemit.com>
---
 drivers/pci/controller/dwc/pcie-spacemit-k1.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-spacemit-k1.c b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
index 0564c46e2f48..98f067e1ba81 100644
--- a/drivers/pci/controller/dwc/pcie-spacemit-k1.c
+++ b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
@@ -44,6 +44,7 @@
 
 #define PCIE_CONTROL_LOGIC			0x0004
 #define PCIE_SOFT_RESET			BIT(0)
+#define PCIE_IGNORE_PERSTN			BIT(2)
 
 struct k1_pcie {
 	struct dw_pcie pci;
@@ -137,6 +138,13 @@ static int k1_pcie_init(struct dw_pcie_rp *pp)
 	if (ret)
 		return ret;
 
+	/*
+	 * When set to 1, the PCIe controller and PHY ignore the PERST signal
+	 * from the link partner in both RC and EP modes.
+	 */
+	regmap_set_bits(k1->pmu, k1->pmu_off + PCIE_CONTROL_LOGIC,
+			PCIE_IGNORE_PERSTN);
+
 	/* Set the PCI vendor and device ID */
 	dw_pcie_dbi_ro_wr_en(pci);
 	dw_pcie_writew_dbi(pci, PCI_VENDOR_ID, PCI_VENDOR_ID_SPACEMIT);

---
base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
change-id: 20260921-spacemit-k1-pcie-fix-256ffa8d382d

Best regards,
-- 
Encrow Thorne <encrow.thorne@linux.spacemit.com>

Re: [PATCH] PCI: spacemit: Ignore link partner PERST on K1

[Troy Mitchell]

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On Thu Sep 24, 2026 at 10:04 AM +08, Encrow Thorne wrote:
> The K1 PCIe controller and PHY are affected by the PERST signal from
> the link partner during initialization. With some devices connected,
> this can prevent host initialization from progressing and cause the
> system to hang while probing the PCIe controller.
>
> Set PCIE_IGNORE_PERSTN before accessing the DBI registers. When set,
> this bit makes both the PCIe controller and PHY ignore the PERST
> signal from the link partner.
>
> This allows host initialization to complete without being affected by
> the link partner's PERST state.
>
> Signed-off-by: Encrow Thorne <encrow.thorne@linux.spacemit.com>
Fix tag and reported-by tag [1]?

Link: https://lore.kernel.org/all/20260825052249.66921-1-bbanelli@gmail.com/ [1]

-- 
Troy Mitchell


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Re: [PATCH] PCI: spacemit: Ignore link partner PERST on K1

[Encrow Thorne]

On Thu Sep 24, 2026 at 10:23 AM CST, Troy Mitchell wrote:
> On Thu Sep 24, 2026 at 10:04 AM +08, Encrow Thorne wrote:
>> The K1 PCIe controller and PHY are affected by the PERST signal from
>> the link partner during initialization. With some devices connected,
>> this can prevent host initialization from progressing and cause the
>> system to hang while probing the PCIe controller.
>>
>> Set PCIE_IGNORE_PERSTN before accessing the DBI registers. When set,
>> this bit makes both the PCIe controller and PHY ignore the PERST
>> signal from the link partner.
>>
>> This allows host initialization to complete without being affected by
>> the link partner's PERST state.
>>
>> Signed-off-by: Encrow Thorne <encrow.thorne@linux.spacemit.com>
> Fix tag and reported-by tag [1]?
>
> Link: https://lore.kernel.org/all/20260825052249.66921-1-bbanelli@gmail.com/ [1]

Thanks, I will add it in the next version.

Re: [PATCH] PCI: spacemit: Ignore link partner PERST on K1

[Manivannan Sadhasivam]

On 2026-09-24 10:04 +0800, Encrow Thorne wrote:
> The K1 PCIe controller and PHY are affected by the PERST signal from
> the link partner during initialization. With some devices connected,
> this can prevent host initialization from progressing and cause the
> system to hang while probing the PCIe controller.
> 
> Set PCIE_IGNORE_PERSTN before accessing the DBI registers. When set,
> this bit makes both the PCIe controller and PHY ignore the PERST
> signal from the link partner.
> 
> This allows host initialization to complete without being affected by
> the link partner's PERST state.
> 
> Signed-off-by: Encrow Thorne <encrow.thorne@linux.spacemit.com>
> ---
>  drivers/pci/controller/dwc/pcie-spacemit-k1.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-spacemit-k1.c b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> index 0564c46e2f48..98f067e1ba81 100644
> --- a/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> +++ b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
> @@ -44,6 +44,7 @@
>  
>  #define PCIE_CONTROL_LOGIC			0x0004
>  #define PCIE_SOFT_RESET			BIT(0)
> +#define PCIE_IGNORE_PERSTN			BIT(2)
>  
>  struct k1_pcie {
>  	struct dw_pcie pci;
> @@ -137,6 +138,13 @@ static int k1_pcie_init(struct dw_pcie_rp *pp)
>  	if (ret)
>  		return ret;
>  
> +	/*
> +	 * When set to 1, the PCIe controller and PHY ignore the PERST signal
> +	 * from the link partner in both RC and EP modes.
> +	 */

What? PERST# is an output signal to RC and input to Endpoint. PERST# is not
controlled by the Endpoint, but only by the RC/host.

- Mani

Re: [PATCH] PCI: spacemit: Ignore link partner PERST on K1

[Encrow Thorne]

On Sun Oct 18, 2026 at 12:26 PM CST, Manivannan Sadhasivam wrote:
> On 2026-09-24 10:04 +0800, Encrow Thorne wrote:
>> The K1 PCIe controller and PHY are affected by the PERST signal from
>> the link partner during initialization. With some devices connected,
>> this can prevent host initialization from progressing and cause the
>> system to hang while probing the PCIe controller.
>> 
>> Set PCIE_IGNORE_PERSTN before accessing the DBI registers. When set,
>> this bit makes both the PCIe controller and PHY ignore the PERST
>> signal from the link partner.
>> 
>> This allows host initialization to complete without being affected by
>> the link partner's PERST state.
>> 
>> Signed-off-by: Encrow Thorne <encrow.thorne@linux.spacemit.com>
>> ---
>>  drivers/pci/controller/dwc/pcie-spacemit-k1.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>> 
>> diff --git a/drivers/pci/controller/dwc/pcie-spacemit-k1.c b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
>> index 0564c46e2f48..98f067e1ba81 100644
>> --- a/drivers/pci/controller/dwc/pcie-spacemit-k1.c
>> +++ b/drivers/pci/controller/dwc/pcie-spacemit-k1.c
>> @@ -44,6 +44,7 @@
>>  
>>  #define PCIE_CONTROL_LOGIC			0x0004
>>  #define PCIE_SOFT_RESET			BIT(0)
>> +#define PCIE_IGNORE_PERSTN			BIT(2)
>>  
>>  struct k1_pcie {
>>  	struct dw_pcie pci;
>> @@ -137,6 +138,13 @@ static int k1_pcie_init(struct dw_pcie_rp *pp)
>>  	if (ret)
>>  		return ret;
>>  
>> +	/*
>> +	 * When set to 1, the PCIe controller and PHY ignore the PERST signal
>> +	 * from the link partner in both RC and EP modes.
>> +	 */
>
Hi Mani

> What? PERST# is an output signal to RC and input to Endpoint. PERST# is not
> controlled by the Endpoint, but only by the RC/host.
>
> - Mani

You are right; my earlier wording was misleading.

On K1, the PERST# pad input feeds back into the local controller's
internal reset input even in RC mode. Thus, the RC can reset itself
when asserting PERST# to reset the endpoint.

PCIE_IGNORE_PERSTN masks this input path without affecting the
RC's control of the external PERST# signal.

Regards,
Encrow Thorne