Re: [PATCH v2 2/8] PCI: cadence: LGA: Add max_link_speed field and 100 ms delay after link training

[Hans Zhang <18255117159@163.com>]

On 5/6/26 23:31, Biju Das wrote:
> 
> 
>> -----Original Message-----
>> From: linux-arm-kernel <linux-arm-kernel-bounces@lists.infradead.org> On Behalf Of Hans Zhang
>> Sent: 06 May 2026 16:24
>> Subject: [PATCH v2 2/8] PCI: cadence: LGA: Add max_link_speed field and 100 ms delay after link
>> training
>>
>> The Cadence LGA (Legacy Architecture IP) PCIe host controller currently lacks the mandatory 100 ms
>> delay after link training completes for speeds
>>> 5.0 GT/s, as required by PCIe r6.0 sec 6.6.1.
>>
>> Add a 'max_link_speed' field to struct cdns_pcie to record the maximum supported link speed (or the
>> currently configured speed). In the common host layer function cdns_pcie_host_start_link(), after the
>> link has been successfully established, call pcie_wait_after_link_train() to insert the required delay
>> if max_link_speed > 2.
>>
>> Glue drivers must set max_link_speed appropriately (e.g., from the device tree property "max-link-
>> speed") to enable the delay.
>>
>> Signed-off-by: Hans Zhang <18255117159@163.com>
>> ---
>>   drivers/pci/controller/cadence/pcie-cadence-host-common.c | 4 ++++
>>   drivers/pci/controller/cadence/pcie-cadence.h             | 2 ++
>>   2 files changed, 6 insertions(+)
>>
>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host-common.c
>> b/drivers/pci/controller/cadence/pcie-cadence-host-common.c
>> index 2b0211870f02..51376f69d007 100644
>> --- a/drivers/pci/controller/cadence/pcie-cadence-host-common.c
>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host-common.c
>> @@ -14,6 +14,7 @@
>>
>>   #include "pcie-cadence.h"
>>   #include "pcie-cadence-host-common.h"
>> +#include "../../pci.h"
>>
>>   #define LINK_RETRAIN_TIMEOUT HZ
>>
>> @@ -115,6 +116,9 @@ int cdns_pcie_host_start_link(struct cdns_pcie_rc *rc,
>>   	if (!ret && rc->quirk_retrain_flag)
>>   		ret = cdns_pcie_retrain(pcie, pcie_link_up);
>>
>> +	if (!ret)
>> +		pcie_wait_after_link_train(pcie->max_link_speed);
>> +
>>   	return ret;
>>   }
>>   EXPORT_SYMBOL_GPL(cdns_pcie_host_start_link);
>> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-
>> cadence.h
>> index 574e9cf4d003..e222b095d2b6 100644
>> --- a/drivers/pci/controller/cadence/pcie-cadence.h
>> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
>> @@ -86,6 +86,7 @@ struct cdns_plat_pcie_of_data {
>>    * @ops: Platform-specific ops to control various inputs from Cadence PCIe
>>    *       wrapper
>>    * @cdns_pcie_reg_offsets: Register bank offsets for different SoC
>> + * @max_link_speed: maximum supported link speed
> 
> Maximum to make consistent with other comments?

Hi Biju,

The reference I used is:

drivers/pci/controller/pcie-rzg3s-host.c
/**
  ......
  * @max_link_speed: maximum supported link speed
  */
struct rzg3s_pcie_host {
......


> 
> 
>>    */
>>   struct cdns_pcie {
>>   	void __iomem		             *reg_base;
>> @@ -98,6 +99,7 @@ struct cdns_pcie {
>>   	struct device_link	             **link;
>>   	const  struct cdns_pcie_ops          *ops;
>>   	const  struct cdns_plat_pcie_of_data *cdns_pcie_reg_offsets;
>> +	int				     max_link_speed;
> 
> unsigned int as speed cannot be negative??

The following file referred to:

drivers/pci/controller/dwc/pcie-designware.h
struct dw_pcie {
     ......
     int			max_link_speed;
     ......
};


Best regards,
Hans
> 
> Cheers,
> Biju
> 
>>   };
>>
>>   /**
>> --
>> 2.34.1
>>