[PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[Kevin Xie]

Add the PCIE_CONFIG_REQUEST_WAIT_MS marco to define the minimum waiting
time between sending the first configuration request to the device and
exit from a conventional reset (or after link training completes).

As described in the conventional reset rules of PCI specifications,
there are two different use cases of the value:

   - With a downstream port that supports link speeds <= 5.0 GT/s,
     the waiting is following exit from a conventional reset.

   - With a downstream port that supports link speeds > 5.0 GT/s,
     the waiting is after link training completes.

Signed-off-by: Kevin Xie <kevin.xie@starfivetech.com>
Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
---
 drivers/pci/pci.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 5ecbcf041179..4ca8766e546e 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -22,6 +22,13 @@
  */
 #define PCIE_PME_TO_L2_TIMEOUT_US	10000
 
+/*
+ * PCIe r6.0, sec 6.6.1, <Conventional Reset>
+ * Requires a minimum waiting of 100ms before sending a configuration
+ * request to the device.
+ */
+#define PCIE_CONFIG_REQUEST_WAIT_MS	100
+
 extern const unsigned char pcie_link_speed[];
 extern bool pci_early_dump;
 
-- 
2.25.1

Re: [PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[Bjorn Helgaas]

On Fri, Nov 24, 2023 at 09:45:08AM +0800, Kevin Xie wrote:
> Add the PCIE_CONFIG_REQUEST_WAIT_MS marco to define the minimum waiting
> time between sending the first configuration request to the device and
> exit from a conventional reset (or after link training completes).

s/marco/macro/

List the first event before the second one, i.e., the delay is from
exit from reset to the config request.

> As described in the conventional reset rules of PCI specifications,
> there are two different use cases of the value:
> 
>    - With a downstream port that supports link speeds <= 5.0 GT/s,
>      the waiting is following exit from a conventional reset.
> 
>    - With a downstream port that supports link speeds > 5.0 GT/s,
>      the waiting is after link training completes.

Include the spec citation here as well as in the comment below.

I assume there are follow-on patches that actually use this?  Can we
make this the first patch in a series so we know we don't have an
unused macro lying around?

> Signed-off-by: Kevin Xie <kevin.xie@starfivetech.com>
> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> ---
>  drivers/pci/pci.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 5ecbcf041179..4ca8766e546e 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -22,6 +22,13 @@
>   */
>  #define PCIE_PME_TO_L2_TIMEOUT_US	10000
>  
> +/*
> + * PCIe r6.0, sec 6.6.1, <Conventional Reset>
> + * Requires a minimum waiting of 100ms before sending a configuration
> + * request to the device.
> + */
> +#define PCIE_CONFIG_REQUEST_WAIT_MS	100
> +
>  extern const unsigned char pcie_link_speed[];
>  extern bool pci_early_dump;
>  
> -- 
> 2.25.1
> 

Re: [PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[Kevin Xie]

On 2023/11/30 7:21, Bjorn Helgaas wrote:
> On Fri, Nov 24, 2023 at 09:45:08AM +0800, Kevin Xie wrote:
>> Add the PCIE_CONFIG_REQUEST_WAIT_MS marco to define the minimum waiting
>> time between sending the first configuration request to the device and
>> exit from a conventional reset (or after link training completes).
> 
> s/marco/macro/
> 
> List the first event before the second one, i.e., the delay is from
> exit from reset to the config request.
> 

OK，I will use "from A to B" instead of "between A and B".

>> As described in the conventional reset rules of PCI specifications,
>> there are two different use cases of the value:
>> 
>>    - With a downstream port that supports link speeds <= 5.0 GT/s,
>>      the waiting is following exit from a conventional reset.
>> 
>>    - With a downstream port that supports link speeds > 5.0 GT/s,
>>      the waiting is after link training completes.
> 
> Include the spec citation here as well as in the comment below.
> 

OK, I will include the spec citation here.

> I assume there are follow-on patches that actually use this?  Can we
> make this the first patch in a series so we know we don't have an
> unused macro lying around?
> 

Yes, we will use the marco in the next version of our PCIe controller patches.
Here is the link of current version patch series:
https://lore.kernel.org/lkml/20231115114912.71448-20-minda.chen@starfivetech.com/T/#u 

Do you mean that I should put this patch back to the above series as one of the separate patches?

Thanks for your review.

>> Signed-off-by: Kevin Xie <kevin.xie@starfivetech.com>
>> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
>> ---
>>  drivers/pci/pci.h | 7 +++++++
>>  1 file changed, 7 insertions(+)
>> 
>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>> index 5ecbcf041179..4ca8766e546e 100644
>> --- a/drivers/pci/pci.h
>> +++ b/drivers/pci/pci.h
>> @@ -22,6 +22,13 @@
>>   */
>>  #define PCIE_PME_TO_L2_TIMEOUT_US	10000
>>  
>> +/*
>> + * PCIe r6.0, sec 6.6.1, <Conventional Reset>
>> + * Requires a minimum waiting of 100ms before sending a configuration
>> + * request to the device.
>> + */
>> +#define PCIE_CONFIG_REQUEST_WAIT_MS	100
>> +
>>  extern const unsigned char pcie_link_speed[];
>>  extern bool pci_early_dump;
>>  
>> -- 
>> 2.25.1
>> 

Re: [PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[Bjorn Helgaas]

On Thu, Nov 30, 2023 at 06:03:55PM +0800, Kevin Xie wrote:
> On 2023/11/30 7:21, Bjorn Helgaas wrote:
> > On Fri, Nov 24, 2023 at 09:45:08AM +0800, Kevin Xie wrote:
> >> Add the PCIE_CONFIG_REQUEST_WAIT_MS marco to define the minimum waiting
> >> time between sending the first configuration request to the device and
> >> exit from a conventional reset (or after link training completes).
> > 
> > s/marco/macro/
> > 
> > List the first event before the second one, i.e., the delay is from
> > exit from reset to the config request.
> 
> OK，I will use "from A to B" instead of "between A and B".

That's not my point.

My point was you said "between B (config request) and A (exit from
reset)".  "A" happens first, so it should be mentioned first.

> > I assume there are follow-on patches that actually use this?  Can we
> > make this the first patch in a series so we know we don't have an
> > unused macro lying around?
> 
> Yes, we will use the marco in the next version of our PCIe controller patches.
> Here is the link of current version patch series:
> https://lore.kernel.org/lkml/20231115114912.71448-20-minda.chen@starfivetech.com/T/#u 
> 
> Do you mean that I should put this patch back to the above series as
> one of the separate patches?

Yes, please.  Handling them as a group is less overhead and helps
avoid merge issues (if they're all in a series there's no possibility
that the user gets merged before the macro itself).

Bjorn

Re: [PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[Kevin Xie]

On 2023/12/1 2:35, Bjorn Helgaas wrote:
> On Thu, Nov 30, 2023 at 06:03:55PM +0800, Kevin Xie wrote:
>> On 2023/11/30 7:21, Bjorn Helgaas wrote:
>> > On Fri, Nov 24, 2023 at 09:45:08AM +0800, Kevin Xie wrote:
>> >> Add the PCIE_CONFIG_REQUEST_WAIT_MS marco to define the minimum waiting
>> >> time between sending the first configuration request to the device and
>> >> exit from a conventional reset (or after link training completes).
>> > 
>> > s/marco/macro/
>> > 
>> > List the first event before the second one, i.e., the delay is from
>> > exit from reset to the config request.
>> 
>> OK，I will use "from A to B" instead of "between A and B".
> 
> That's not my point.
> 
> My point was you said "between B (config request) and A (exit from
> reset)".  "A" happens first, so it should be mentioned first.
> 

Got it.

>> > I assume there are follow-on patches that actually use this?  Can we
>> > make this the first patch in a series so we know we don't have an
>> > unused macro lying around?
>> 
>> Yes, we will use the marco in the next version of our PCIe controller patches.
>> Here is the link of current version patch series:
>> https://lore.kernel.org/lkml/20231115114912.71448-20-minda.chen@starfivetech.com/T/#u 
>> 
>> Do you mean that I should put this patch back to the above series as
>> one of the separate patches?
> 
> Yes, please.  Handling them as a group is less overhead and helps
> avoid merge issues (if they're all in a series there's no possibility
> that the user gets merged before the macro itself).
> 

OK, I will put the patch back with these changes.

> Bjorn

Re: [PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[Bjorn Helgaas]

On Fri, Nov 24, 2023 at 09:45:08AM +0800, Kevin Xie wrote:
> Add the PCIE_CONFIG_REQUEST_WAIT_MS marco to define the minimum waiting
> time between sending the first configuration request to the device and
> exit from a conventional reset (or after link training completes).
> 
> As described in the conventional reset rules of PCI specifications,
> there are two different use cases of the value:
> 
>    - With a downstream port that supports link speeds <= 5.0 GT/s,
>      the waiting is following exit from a conventional reset.
> 
>    - With a downstream port that supports link speeds > 5.0 GT/s,
>      the waiting is after link training completes.
> 
> Signed-off-by: Kevin Xie <kevin.xie@starfivetech.com>
> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> ---
>  drivers/pci/pci.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 5ecbcf041179..4ca8766e546e 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -22,6 +22,13 @@
>   */
>  #define PCIE_PME_TO_L2_TIMEOUT_US	10000
>  
> +/*
> + * PCIe r6.0, sec 6.6.1, <Conventional Reset>
> + * Requires a minimum waiting of 100ms before sending a configuration
> + * request to the device.
> + */
> +#define PCIE_CONFIG_REQUEST_WAIT_MS	100

Oh, and I think this name should include something about "reset"
because that's the common scenario and that's the spec section where
the value is mentioned.

Re: [PATCH v1] PCI: Add PCIE_CONFIG_REQUEST_WAIT_MS waiting time value

[Kevin Xie]

On 2023/11/30 7:22, Bjorn Helgaas wrote:
> On Fri, Nov 24, 2023 at 09:45:08AM +0800, Kevin Xie wrote:
>> Add the PCIE_CONFIG_REQUEST_WAIT_MS marco to define the minimum waiting
>> time between sending the first configuration request to the device and
>> exit from a conventional reset (or after link training completes).
>> 
>> As described in the conventional reset rules of PCI specifications,
>> there are two different use cases of the value:
>> 
>>    - With a downstream port that supports link speeds <= 5.0 GT/s,
>>      the waiting is following exit from a conventional reset.
>> 
>>    - With a downstream port that supports link speeds > 5.0 GT/s,
>>      the waiting is after link training completes.
>> 
>> Signed-off-by: Kevin Xie <kevin.xie@starfivetech.com>
>> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
>> ---
>>  drivers/pci/pci.h | 7 +++++++
>>  1 file changed, 7 insertions(+)
>> 
>> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
>> index 5ecbcf041179..4ca8766e546e 100644
>> --- a/drivers/pci/pci.h
>> +++ b/drivers/pci/pci.h
>> @@ -22,6 +22,13 @@
>>   */
>>  #define PCIE_PME_TO_L2_TIMEOUT_US	10000
>>  
>> +/*
>> + * PCIe r6.0, sec 6.6.1, <Conventional Reset>
>> + * Requires a minimum waiting of 100ms before sending a configuration
>> + * request to the device.
>> + */
>> +#define PCIE_CONFIG_REQUEST_WAIT_MS	100
> 
> Oh, and I think this name should include something about "reset"
> because that's the common scenario and that's the spec section where
> the value is mentioned.

Agree, how about PCIE_RESET_CONFIG_DEVICE_WAIT_MS?