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

[Manivannan Sadhasivam]

On Wed, May 06, 2026 at 11:23:40PM +0800, Hans Zhang wrote:
> 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.
> 

You need to club those glue driver patches into this one. Otherwise, you'll end
up breaking bisectability.

- Mani

> Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
> ---
>  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
>   */
>  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;
>  };
>  
>  /**
> -- 
> 2.34.1
> 

-- 
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