* [PATCH] PCI: cadence: skip the link polling when endpoint not connected
@ 2026-06-05 7:19 Aksh Garg
2026-06-08 6:26 ` Chen Wang
2026-06-09 3:42 ` Siddharth Vadapalli
0 siblings, 2 replies; 6+ messages in thread
From: Aksh Garg @ 2026-06-05 7:19 UTC (permalink / raw)
To: linux-pci, vigneshr, s-vadapalli, lpieralisi, kwilczynski, mani,
robh, bhelgaas, mpillai, unicorn_wang, me, 18255117159
Cc: linux-arm-kernel, linux-kernel, danishanwar, a-garg7
cdns_pcie_host_wait_for_link() polls on link-up for 10 retries with a
delay of 90-100ms each (~1 second). A call to cdns_pcie_host_link_setup()
during the resume operation blocks the resume operation unnecessarily for
~1s even when no endpoint device is connected.
Add skip_link_polling flag to track link state across suspend/resume
cycles. If link was down before suspend, skip the expensive polling
in resume since no endpoint was present.
Signed-off-by: Aksh Garg <a-garg7@ti.com>
---
drivers/pci/controller/cadence/pci-j721e.c | 5 +++++
drivers/pci/controller/cadence/pcie-cadence-host-hpa.c | 3 +++
drivers/pci/controller/cadence/pcie-cadence-host.c | 3 +++
drivers/pci/controller/cadence/pcie-cadence.h | 3 +++
4 files changed, 14 insertions(+)
diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
index bfdfe98d5aba..849eb8bb9e45 100644
--- a/drivers/pci/controller/cadence/pci-j721e.c
+++ b/drivers/pci/controller/cadence/pci-j721e.c
@@ -686,6 +686,11 @@ static int j721e_pcie_suspend_noirq(struct device *dev)
struct j721e_pcie *pcie = dev_get_drvdata(dev);
if (pcie->mode == PCI_MODE_RC) {
+ struct cdns_pcie_rc *rc = cdns_pcie_to_rc(pcie->cdns_pcie);
+
+ /* If link is down before suspend, skip polling in resume */
+ rc->skip_link_polling = !j721e_pcie_link_up(pcie->cdns_pcie);
+
gpiod_set_value_cansleep(pcie->reset_gpio, 0);
clk_disable_unprepare(pcie->refclk);
}
diff --git a/drivers/pci/controller/cadence/pcie-cadence-host-hpa.c b/drivers/pci/controller/cadence/pcie-cadence-host-hpa.c
index 0f540bed58e8..d78c1282a5ee 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host-hpa.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host-hpa.c
@@ -301,6 +301,9 @@ int cdns_pcie_hpa_host_link_setup(struct cdns_pcie_rc *rc)
return ret;
}
+ if (rc->skip_link_polling)
+ return 0;
+
ret = cdns_pcie_host_wait_for_link(pcie, cdns_pcie_hpa_link_up);
if (ret)
dev_dbg(dev, "PCIe link never came up\n");
diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index 0bc9e6e90e0e..026414c21ee1 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -352,6 +352,9 @@ int cdns_pcie_host_link_setup(struct cdns_pcie_rc *rc)
return ret;
}
+ if (rc->skip_link_polling)
+ return 0;
+
ret = cdns_pcie_host_start_link(rc, cdns_pcie_link_up);
if (ret)
dev_dbg(dev, "PCIe link never came up\n");
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index 574e9cf4d003..01e49ecccc7b 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -117,6 +117,8 @@ struct cdns_pcie {
* @no_inbound_map: Whether inbound mapping is supported
* @quirk_broken_aspm_l0s: Disable ASPM L0s support as quirk
* @quirk_broken_aspm_l1: Disable ASPM L1 support as quirk
+ * @skip_link_polling: Skip link polling in resume if link was down before
+ * suspend, to avoid long delay in resume
*/
struct cdns_pcie_rc {
struct cdns_pcie pcie;
@@ -131,6 +133,7 @@ struct cdns_pcie_rc {
unsigned int no_inbound_map:1;
unsigned int quirk_broken_aspm_l0s:1;
unsigned int quirk_broken_aspm_l1:1;
+ unsigned int skip_link_polling:1;
};
/**
--
2.34.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] PCI: cadence: skip the link polling when endpoint not connected
2026-06-05 7:19 [PATCH] PCI: cadence: skip the link polling when endpoint not connected Aksh Garg
@ 2026-06-08 6:26 ` Chen Wang
2026-06-09 3:42 ` Siddharth Vadapalli
1 sibling, 0 replies; 6+ messages in thread
From: Chen Wang @ 2026-06-08 6:26 UTC (permalink / raw)
To: Aksh Garg, linux-pci, vigneshr, s-vadapalli, lpieralisi,
kwilczynski, mani, robh, bhelgaas, mpillai, me, 18255117159
Cc: linux-arm-kernel, linux-kernel, danishanwar
On 6/5/2026 3:19 PM, Aksh Garg wrote:
> cdns_pcie_host_wait_for_link() polls on link-up for 10 retries with a
> delay of 90-100ms each (~1 second). A call to cdns_pcie_host_link_setup()
> during the resume operation blocks the resume operation unnecessarily for
> ~1s even when no endpoint device is connected.
>
> Add skip_link_polling flag to track link state across suspend/resume
> cycles. If link was down before suspend, skip the expensive polling
> in resume since no endpoint was present.
>
> Signed-off-by: Aksh Garg <a-garg7@ti.com>
Reviewed-by: Chen Wang <unicorn_wang@outlook.com>
[......]
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] PCI: cadence: skip the link polling when endpoint not connected
2026-06-05 7:19 [PATCH] PCI: cadence: skip the link polling when endpoint not connected Aksh Garg
2026-06-08 6:26 ` Chen Wang
@ 2026-06-09 3:42 ` Siddharth Vadapalli
2026-06-09 4:28 ` Aksh Garg
1 sibling, 1 reply; 6+ messages in thread
From: Siddharth Vadapalli @ 2026-06-09 3:42 UTC (permalink / raw)
To: Aksh Garg
Cc: vigneshr, lpieralisi, kwilczynski, mani, robh, bhelgaas, mpillai,
unicorn_wang, me, 18255117159, linux-pci, linux-arm-kernel,
linux-kernel, danishanwar, s-vadapalli
On 05/06/26 12:49, Aksh Garg wrote:
> cdns_pcie_host_wait_for_link() polls on link-up for 10 retries with a
> delay of 90-100ms each (~1 second). A call to cdns_pcie_host_link_setup()
> during the resume operation blocks the resume operation unnecessarily for
> ~1s even when no endpoint device is connected.
>
> Add skip_link_polling flag to track link state across suspend/resume
> cycles. If link was down before suspend, skip the expensive polling
> in resume since no endpoint was present.
>
> Signed-off-by: Aksh Garg <a-garg7@ti.com>
> ---
> drivers/pci/controller/cadence/pci-j721e.c | 5 +++++
> drivers/pci/controller/cadence/pcie-cadence-host-hpa.c | 3 +++
> drivers/pci/controller/cadence/pcie-cadence-host.c | 3 +++
> drivers/pci/controller/cadence/pcie-cadence.h | 3 +++
> 4 files changed, 14 insertions(+)
>
> diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
> index bfdfe98d5aba..849eb8bb9e45 100644
> --- a/drivers/pci/controller/cadence/pci-j721e.c
> +++ b/drivers/pci/controller/cadence/pci-j721e.c
> @@ -686,6 +686,11 @@ static int j721e_pcie_suspend_noirq(struct device *dev)
> struct j721e_pcie *pcie = dev_get_drvdata(dev);
>
> if (pcie->mode == PCI_MODE_RC) {
> + struct cdns_pcie_rc *rc = cdns_pcie_to_rc(pcie->cdns_pcie);
> +
> + /* If link is down before suspend, skip polling in resume */
> + rc->skip_link_polling = !j721e_pcie_link_up(pcie->cdns_pcie);
> +
Please consider the following scenario:
1. Endpoint device is not connected initially and we suspend with
'skip_link_polling' set to true.
2. We resume and skip link polling.
3. An Endpoint device is connected to the PCIe Connector a while later.
4. We perform a bus rescan, but with skip_link_polling still set (in
resume), wouldn't we skip polling for the link to be up?
Shouldn't 'skip_link_polling' be set to false on resume, after we skip the
polling initially, in order to allow waiting for a link up for a newly
connected device? Although this may not be done in practice and the
Endpoint device may always be left connected from the start, I am wondering
if we should clear 'skip_link_polling' on resume to account for the
aforementioned scenario. Let me know if I am overlooking something here.
> gpiod_set_value_cansleep(pcie->reset_gpio, 0);
> clk_disable_unprepare(pcie->refclk);
> }
[TRIMMED]
Regards,
Siddharth.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] PCI: cadence: skip the link polling when endpoint not connected
2026-06-09 3:42 ` Siddharth Vadapalli
@ 2026-06-09 4:28 ` Aksh Garg
2026-06-09 5:11 ` Siddharth Vadapalli
0 siblings, 1 reply; 6+ messages in thread
From: Aksh Garg @ 2026-06-09 4:28 UTC (permalink / raw)
To: Siddharth Vadapalli
Cc: vigneshr, lpieralisi, kwilczynski, mani, robh, bhelgaas, mpillai,
unicorn_wang, me, 18255117159, linux-pci, linux-arm-kernel,
linux-kernel, danishanwar
On 09/06/26 09:12, Siddharth Vadapalli wrote:
> On 05/06/26 12:49, Aksh Garg wrote:
>> cdns_pcie_host_wait_for_link() polls on link-up for 10 retries with a
>> delay of 90-100ms each (~1 second). A call to cdns_pcie_host_link_setup()
>> during the resume operation blocks the resume operation unnecessarily for
>> ~1s even when no endpoint device is connected.
>>
>> Add skip_link_polling flag to track link state across suspend/resume
>> cycles. If link was down before suspend, skip the expensive polling
>> in resume since no endpoint was present.
>>
>> Signed-off-by: Aksh Garg <a-garg7@ti.com>
>> ---
>> drivers/pci/controller/cadence/pci-j721e.c | 5 +++++
>> drivers/pci/controller/cadence/pcie-cadence-host-hpa.c | 3 +++
>> drivers/pci/controller/cadence/pcie-cadence-host.c | 3 +++
>> drivers/pci/controller/cadence/pcie-cadence.h | 3 +++
>> 4 files changed, 14 insertions(+)
>>
>> diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/
>> controller/cadence/pci-j721e.c
>> index bfdfe98d5aba..849eb8bb9e45 100644
>> --- a/drivers/pci/controller/cadence/pci-j721e.c
>> +++ b/drivers/pci/controller/cadence/pci-j721e.c
>> @@ -686,6 +686,11 @@ static int j721e_pcie_suspend_noirq(struct device
>> *dev)
>> struct j721e_pcie *pcie = dev_get_drvdata(dev);
>> if (pcie->mode == PCI_MODE_RC) {
>> + struct cdns_pcie_rc *rc = cdns_pcie_to_rc(pcie->cdns_pcie);
>> +
>> + /* If link is down before suspend, skip polling in resume */
>> + rc->skip_link_polling = !j721e_pcie_link_up(pcie->cdns_pcie);
>> +
>
> Please consider the following scenario:
> 1. Endpoint device is not connected initially and we suspend with
> 'skip_link_polling' set to true.
> 2. We resume and skip link polling.
> 3. An Endpoint device is connected to the PCIe Connector a while later.
> 4. We perform a bus rescan, but with skip_link_polling still set (in
> resume), wouldn't we skip polling for the link to be up?
>
> Shouldn't 'skip_link_polling' be set to false on resume, after we skip
> the polling initially, in order to allow waiting for a link up for a
> newly connected device? Although this may not be done in practice and
> the Endpoint device may always be left connected from the start, I am
> wondering if we should clear 'skip_link_polling' on resume to account
> for the aforementioned scenario. Let me know if I am overlooking
> something here.
This path is not used during bus rescan. This implies that during the
rescan, we do not call cdns_pcie_host_link_setup() or
cdns_pcie_hpa_host_link_setup().
>
>> gpiod_set_value_cansleep(pcie->reset_gpio, 0);
>> clk_disable_unprepare(pcie->refclk);
>> }
>
> [TRIMMED]
>
> Regards,
> Siddharth.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] PCI: cadence: skip the link polling when endpoint not connected
2026-06-09 4:28 ` Aksh Garg
@ 2026-06-09 5:11 ` Siddharth Vadapalli
2026-06-09 5:36 ` Manikandan Karunakaran Pillai
0 siblings, 1 reply; 6+ messages in thread
From: Siddharth Vadapalli @ 2026-06-09 5:11 UTC (permalink / raw)
To: Aksh Garg
Cc: s-vadapalli, vigneshr, lpieralisi, kwilczynski, mani, robh,
bhelgaas, mpillai, unicorn_wang, me, 18255117159, linux-pci,
linux-arm-kernel, linux-kernel, danishanwar
On 09/06/26 09:58, Aksh Garg wrote:
>
>
> On 09/06/26 09:12, Siddharth Vadapalli wrote:
>> On 05/06/26 12:49, Aksh Garg wrote:
>>> cdns_pcie_host_wait_for_link() polls on link-up for 10 retries with a
>>> delay of 90-100ms each (~1 second). A call to cdns_pcie_host_link_setup()
>>> during the resume operation blocks the resume operation unnecessarily for
>>> ~1s even when no endpoint device is connected.
>>>
>>> Add skip_link_polling flag to track link state across suspend/resume
>>> cycles. If link was down before suspend, skip the expensive polling
>>> in resume since no endpoint was present.
>>>
>>> Signed-off-by: Aksh Garg <a-garg7@ti.com>
>>> ---
>>> drivers/pci/controller/cadence/pci-j721e.c | 5 +++++
>>> drivers/pci/controller/cadence/pcie-cadence-host-hpa.c | 3 +++
>>> drivers/pci/controller/cadence/pcie-cadence-host.c | 3 +++
>>> drivers/pci/controller/cadence/pcie-cadence.h | 3 +++
>>> 4 files changed, 14 insertions(+)
>>>
>>> diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/
>>> controller/cadence/pci-j721e.c
>>> index bfdfe98d5aba..849eb8bb9e45 100644
>>> --- a/drivers/pci/controller/cadence/pci-j721e.c
>>> +++ b/drivers/pci/controller/cadence/pci-j721e.c
>>> @@ -686,6 +686,11 @@ static int j721e_pcie_suspend_noirq(struct device
>>> *dev)
>>> struct j721e_pcie *pcie = dev_get_drvdata(dev);
>>> if (pcie->mode == PCI_MODE_RC) {
>>> + struct cdns_pcie_rc *rc = cdns_pcie_to_rc(pcie->cdns_pcie);
>>> +
>>> + /* If link is down before suspend, skip polling in resume */
>>> + rc->skip_link_polling = !j721e_pcie_link_up(pcie->cdns_pcie);
>>> +
>>
>> Please consider the following scenario:
>> 1. Endpoint device is not connected initially and we suspend with
>> 'skip_link_polling' set to true.
>> 2. We resume and skip link polling.
>> 3. An Endpoint device is connected to the PCIe Connector a while later.
>> 4. We perform a bus rescan, but with skip_link_polling still set (in
>> resume), wouldn't we skip polling for the link to be up?
>>
>> Shouldn't 'skip_link_polling' be set to false on resume, after we skip
>> the polling initially, in order to allow waiting for a link up for a
>> newly connected device? Although this may not be done in practice and the
>> Endpoint device may always be left connected from the start, I am
>> wondering if we should clear 'skip_link_polling' on resume to account for
>> the aforementioned scenario. Let me know if I am overlooking something here.
>
> This path is not used during bus rescan. This implies that during the
> rescan, we do not call cdns_pcie_host_link_setup() or
> cdns_pcie_hpa_host_link_setup().
Thank you for clarifying.
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Regards,
Siddharth.
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH] PCI: cadence: skip the link polling when endpoint not connected
2026-06-09 5:11 ` Siddharth Vadapalli
@ 2026-06-09 5:36 ` Manikandan Karunakaran Pillai
0 siblings, 0 replies; 6+ messages in thread
From: Manikandan Karunakaran Pillai @ 2026-06-09 5:36 UTC (permalink / raw)
To: Siddharth Vadapalli, Aksh Garg
Cc: vigneshr@ti.com, lpieralisi@kernel.org, kwilczynski@kernel.org,
mani@kernel.org, robh@kernel.org, bhelgaas@google.com,
unicorn_wang@outlook.com, me@ziyao.cc, 18255117159@163.com,
linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, danishanwar@ti.com
>-----Original Message-----
>From: Siddharth Vadapalli <s-vadapalli@ti.com>
>Sent: Tuesday, June 9, 2026 10:42 AM
>To: Aksh Garg <a-garg7@ti.com>
>Cc: s-vadapalli@ti.com; vigneshr@ti.com; lpieralisi@kernel.org;
>kwilczynski@kernel.org; mani@kernel.org; robh@kernel.org;
>bhelgaas@google.com; Manikandan Karunakaran Pillai
><mpillai@cadence.com>; unicorn_wang@outlook.com; me@ziyao.cc;
>18255117159@163.com; linux-pci@vger.kernel.org; linux-arm-
>kernel@lists.infradead.org; linux-kernel@vger.kernel.org; danishanwar@ti.com
>Subject: Re: [PATCH] PCI: cadence: skip the link polling when endpoint not
>connected
>
>EXTERNAL MAIL
>
>
>On 09/06/26 09:58, Aksh Garg wrote:
>>
>>
>> On 09/06/26 09:12, Siddharth Vadapalli wrote:
>>> On 05/06/26 12:49, Aksh Garg wrote:
>>>> cdns_pcie_host_wait_for_link() polls on link-up for 10 retries with a
>>>> delay of 90-100ms each (~1 second). A call to cdns_pcie_host_link_setup()
>>>> during the resume operation blocks the resume operation unnecessarily
>for
>>>> ~1s even when no endpoint device is connected.
>>>>
>>>> Add skip_link_polling flag to track link state across suspend/resume
>>>> cycles. If link was down before suspend, skip the expensive polling
>>>> in resume since no endpoint was present.
>>>>
>>>> Signed-off-by: Aksh Garg <a-garg7@ti.com>
>>>> ---
>>>> drivers/pci/controller/cadence/pci-j721e.c | 5 +++++
>>>> drivers/pci/controller/cadence/pcie-cadence-host-hpa.c | 3 +++
>>>> drivers/pci/controller/cadence/pcie-cadence-host.c | 3 +++
>>>> drivers/pci/controller/cadence/pcie-cadence.h | 3 +++
>>>> 4 files changed, 14 insertions(+)
>>>>
>>>> diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/
>>>> controller/cadence/pci-j721e.c
>>>> index bfdfe98d5aba..849eb8bb9e45 100644
>>>> --- a/drivers/pci/controller/cadence/pci-j721e.c
>>>> +++ b/drivers/pci/controller/cadence/pci-j721e.c
>>>> @@ -686,6 +686,11 @@ static int j721e_pcie_suspend_noirq(struct device
>>>> *dev)
>>>> struct j721e_pcie *pcie = dev_get_drvdata(dev);
>>>> if (pcie->mode == PCI_MODE_RC) {
>>>> + struct cdns_pcie_rc *rc = cdns_pcie_to_rc(pcie->cdns_pcie);
>>>> +
>>>> + /* If link is down before suspend, skip polling in resume */
>>>> + rc->skip_link_polling = !j721e_pcie_link_up(pcie->cdns_pcie);
>>>> +
>>>
>>> Please consider the following scenario:
>>> 1. Endpoint device is not connected initially and we suspend with
>>> 'skip_link_polling' set to true.
>>> 2. We resume and skip link polling.
>>> 3. An Endpoint device is connected to the PCIe Connector a while later.
>>> 4. We perform a bus rescan, but with skip_link_polling still set (in
>>> resume), wouldn't we skip polling for the link to be up?
>>>
>>> Shouldn't 'skip_link_polling' be set to false on resume, after we skip
>>> the polling initially, in order to allow waiting for a link up for a
>>> newly connected device? Although this may not be done in practice and the
>>> Endpoint device may always be left connected from the start, I am
>>> wondering if we should clear 'skip_link_polling' on resume to account for
>>> the aforementioned scenario. Let me know if I am overlooking something
>here.
>>
>> This path is not used during bus rescan. This implies that during the
>> rescan, we do not call cdns_pcie_host_link_setup() or
>> cdns_pcie_hpa_host_link_setup().
>Thank you for clarifying.
>
>Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
>
Looks good to me
>Regards,
>Siddharth.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-06-09 5:37 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2026-06-05 7:19 [PATCH] PCI: cadence: skip the link polling when endpoint not connected Aksh Garg
2026-06-08 6:26 ` Chen Wang
2026-06-09 3:42 ` Siddharth Vadapalli
2026-06-09 4:28 ` Aksh Garg
2026-06-09 5:11 ` Siddharth Vadapalli
2026-06-09 5:36 ` Manikandan Karunakaran Pillai
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