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[PATCH v4 3/4] PCI: pciehp: Add macros for hotplug operation delays

Hans Zhang posted 4 patches 3 months, 1 week ago
[PATCH v4 3/4] PCI: pciehp: Add macros for hotplug operation delays
Posted by Hans Zhang 3 months, 1 week ago 
Add WAIT_PDS_TIMEOUT_MS and POLL_CMD_TIMEOUT_MS macros for hotplug
operation delays to improve code readability.

Signed-off-by: Hans Zhang <18255117159@163.com>
---
 drivers/pci/hotplug/pciehp_hpc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index bcc51b26d03d..15b09c6a8d6b 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -28,6 +28,9 @@
 #include "../pci.h"
 #include "pciehp.h"
 
+#define WAIT_PDS_TIMEOUT_MS	10
+#define POLL_CMD_TIMEOUT_MS	10
+
 static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
 	/*
 	 * Match all Dell systems, as some Dell systems have inband
@@ -103,7 +106,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
 			smp_mb();
 			return 1;
 		}
-		msleep(10);
+		msleep(POLL_CMD_TIMEOUT_MS);
 		timeout -= 10;
 	} while (timeout >= 0);
 	return 0;	/* timeout */
@@ -283,7 +286,7 @@ static void pcie_wait_for_presence(struct pci_dev *pdev)
 		pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
 		if (slot_status & PCI_EXP_SLTSTA_PDS)
 			return;
-		msleep(10);
+		msleep(WAIT_PDS_TIMEOUT_MS);
 		timeout -= 10;
 	} while (timeout > 0);
 }
-- 
2.34.1
Re: [PATCH v4 3/4] PCI: pciehp: Add macros for hotplug operation delays
Posted by Bjorn Helgaas 3 months, 1 week ago 
[+cc Lukas]

On Sun, Nov 02, 2025 at 12:05:37AM +0800, Hans Zhang wrote:
> Add WAIT_PDS_TIMEOUT_MS and POLL_CMD_TIMEOUT_MS macros for hotplug
> operation delays to improve code readability.
> 
> Signed-off-by: Hans Zhang <18255117159@163.com>
> ---
>  drivers/pci/hotplug/pciehp_hpc.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index bcc51b26d03d..15b09c6a8d6b 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -28,6 +28,9 @@
>  #include "../pci.h"
>  #include "pciehp.h"
>  
> +#define WAIT_PDS_TIMEOUT_MS	10
> +#define POLL_CMD_TIMEOUT_MS	10
> +
>  static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
>  	/*
>  	 * Match all Dell systems, as some Dell systems have inband
> @@ -103,7 +106,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>  			smp_mb();
>  			return 1;
>  		}
> -		msleep(10);
> +		msleep(POLL_CMD_TIMEOUT_MS);

Lukas might have different opinions and I would defer to him here.

But IMO (a) these aren't timeouts, they are poll intervals, (b) the
values are arbitrary with no connection to a spec, so less reason for
a #define, and (c) the #defines don't improve readability because now
I have to look at two places to understand the poll loops.

>  		timeout -= 10;
>  	} while (timeout >= 0);
>  	return 0;	/* timeout */
> @@ -283,7 +286,7 @@ static void pcie_wait_for_presence(struct pci_dev *pdev)
>  		pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
>  		if (slot_status & PCI_EXP_SLTSTA_PDS)
>  			return;
> -		msleep(10);
> +		msleep(WAIT_PDS_TIMEOUT_MS);
>  		timeout -= 10;
>  	} while (timeout > 0);
>  }
> -- 
> 2.34.1
>
Re: [PATCH v4 3/4] PCI: pciehp: Add macros for hotplug operation delays
Posted by Lukas Wunner 3 months, 1 week ago 
On Mon, Nov 03, 2025 at 09:37:34AM -0600, Bjorn Helgaas wrote:
> On Sun, Nov 02, 2025 at 12:05:37AM +0800, Hans Zhang wrote:
> > Add WAIT_PDS_TIMEOUT_MS and POLL_CMD_TIMEOUT_MS macros for hotplug
> > operation delays to improve code readability.
[...]
> > +++ b/drivers/pci/hotplug/pciehp_hpc.c
> > @@ -28,6 +28,9 @@
> >  #include "../pci.h"
> >  #include "pciehp.h"
> >  
> > +#define WAIT_PDS_TIMEOUT_MS	10
> > +#define POLL_CMD_TIMEOUT_MS	10
> > +
> >  static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
> >  	/*
> >  	 * Match all Dell systems, as some Dell systems have inband
> > @@ -103,7 +106,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
> >  			smp_mb();
> >  			return 1;
> >  		}
> > -		msleep(10);
> > +		msleep(POLL_CMD_TIMEOUT_MS);
> 
> Lukas might have different opinions and I would defer to him here.
> 
> But IMO (a) these aren't timeouts, they are poll intervals, (b) the
> values are arbitrary with no connection to a spec, so less reason for
> a #define, and (c) the #defines don't improve readability because now
> I have to look at two places to understand the poll loops.

I agree on all counts.

Thanks,

Lukas
Re: [PATCH v4 3/4] PCI: pciehp: Add macros for hotplug operation delays
Posted by Hans Zhang 3 months ago 

On 2025/11/4 01:24, Lukas Wunner wrote:
> On Mon, Nov 03, 2025 at 09:37:34AM -0600, Bjorn Helgaas wrote:
>> On Sun, Nov 02, 2025 at 12:05:37AM +0800, Hans Zhang wrote:
>>> Add WAIT_PDS_TIMEOUT_MS and POLL_CMD_TIMEOUT_MS macros for hotplug
>>> operation delays to improve code readability.
> [...]
>>> +++ b/drivers/pci/hotplug/pciehp_hpc.c
>>> @@ -28,6 +28,9 @@
>>>   #include "../pci.h"
>>>   #include "pciehp.h"
>>>   
>>> +#define WAIT_PDS_TIMEOUT_MS	10
>>> +#define POLL_CMD_TIMEOUT_MS	10
>>> +
>>>   static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
>>>   	/*
>>>   	 * Match all Dell systems, as some Dell systems have inband
>>> @@ -103,7 +106,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>>>   			smp_mb();
>>>   			return 1;
>>>   		}
>>> -		msleep(10);
>>> +		msleep(POLL_CMD_TIMEOUT_MS);
>>
>> Lukas might have different opinions and I would defer to him here.
>>
>> But IMO (a) these aren't timeouts, they are poll intervals, (b) the
>> values are arbitrary with no connection to a spec, so less reason for
>> a #define, and (c) the #defines don't improve readability because now
>> I have to look at two places to understand the poll loops.
> 
> I agree on all counts.
> 

Hi Bjorn,

Please drop this patch.

Best regards,
Hans


> Thanks,
> 
> Lukas
Re: [PATCH v4 3/4] PCI: pciehp: Add macros for hotplug operation delays
Posted by Christophe JAILLET 3 months, 1 week ago 
Le 01/11/2025 à 17:05, Hans Zhang a écrit :
> Add WAIT_PDS_TIMEOUT_MS and POLL_CMD_TIMEOUT_MS macros for hotplug
> operation delays to improve code readability.
> 
> Signed-off-by: Hans Zhang <18255117159@163.com>
> ---
>   drivers/pci/hotplug/pciehp_hpc.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
> index bcc51b26d03d..15b09c6a8d6b 100644
> --- a/drivers/pci/hotplug/pciehp_hpc.c
> +++ b/drivers/pci/hotplug/pciehp_hpc.c
> @@ -28,6 +28,9 @@
>   #include "../pci.h"
>   #include "pciehp.h"
>   
> +#define WAIT_PDS_TIMEOUT_MS	10
> +#define POLL_CMD_TIMEOUT_MS	10
> +
>   static const struct dmi_system_id inband_presence_disabled_dmi_table[] = {
>   	/*
>   	 * Match all Dell systems, as some Dell systems have inband
> @@ -103,7 +106,7 @@ static int pcie_poll_cmd(struct controller *ctrl, int timeout)
>   			smp_mb();
>   			return 1;
>   		}
> -		msleep(10);
> +		msleep(POLL_CMD_TIMEOUT_MS);
>   		timeout -= 10;

Should we have: timeout -= POLL_CMD_TIMEOUT_MS;

?

>   	} while (timeout >= 0);
>   	return 0;	/* timeout */
> @@ -283,7 +286,7 @@ static void pcie_wait_for_presence(struct pci_dev *pdev)
>   		pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
>   		if (slot_status & PCI_EXP_SLTSTA_PDS)
>   			return;
> -		msleep(10);
> +		msleep(WAIT_PDS_TIMEOUT_MS);

Same with WAIT_PDS_TIMEOUT_MS.

CJ

>   		timeout -= 10;
>   	} while (timeout > 0);
>   }
Re: [PATCH v4 3/4] PCI: pciehp: Add macros for hotplug operation delays
Posted by Hans Zhang 3 months, 1 week ago 

On 2025/11/2 00:13, Christophe JAILLET wrote:
> Le 01/11/2025 à 17:05, Hans Zhang a écrit :
>> Add WAIT_PDS_TIMEOUT_MS and POLL_CMD_TIMEOUT_MS macros for hotplug
>> operation delays to improve code readability.
>>
>> Signed-off-by: Hans Zhang <18255117159@163.com>
>> ---
>>   drivers/pci/hotplug/pciehp_hpc.c | 7 +++++--
>>   1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/ 
>> pciehp_hpc.c
>> index bcc51b26d03d..15b09c6a8d6b 100644
>> --- a/drivers/pci/hotplug/pciehp_hpc.c
>> +++ b/drivers/pci/hotplug/pciehp_hpc.c
>> @@ -28,6 +28,9 @@
>>   #include "../pci.h"
>>   #include "pciehp.h"
>> +#define WAIT_PDS_TIMEOUT_MS    10
>> +#define POLL_CMD_TIMEOUT_MS    10
>> +
>>   static const struct dmi_system_id 
>> inband_presence_disabled_dmi_table[] = {
>>       /*
>>        * Match all Dell systems, as some Dell systems have inband
>> @@ -103,7 +106,7 @@ static int pcie_poll_cmd(struct controller *ctrl, 
>> int timeout)
>>               smp_mb();
>>               return 1;
>>           }
>> -        msleep(10);
>> +        msleep(POLL_CMD_TIMEOUT_MS);
>>           timeout -= 10;
> 
> Should we have: timeout -= POLL_CMD_TIMEOUT_MS;
> 
> ?

Hi Christophe,

Thank you very much for your reply and reminder.

If Bjorn finds it meaningful, I will fix it in the next version.


> 
>>       } while (timeout >= 0);
>>       return 0;    /* timeout */
>> @@ -283,7 +286,7 @@ static void pcie_wait_for_presence(struct pci_dev 
>> *pdev)
>>           pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
>>           if (slot_status & PCI_EXP_SLTSTA_PDS)
>>               return;
>> -        msleep(10);
>> +        msleep(WAIT_PDS_TIMEOUT_MS);
> 
> Same with WAIT_PDS_TIMEOUT_MS.
> 

Will change.

Best regards,
Hans

> CJ
> 
>>           timeout -= 10;
>>       } while (timeout > 0);
>>   }

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