Re: [PATCH v3 1/2] PCI: cadence: Add flags for disabling ASPM support advertisement

[Chen Wang <unicorn_wang@outlook.com>]

On 4/5/2026 11:41 PM, Yao Zi wrote:
> Add flags for disabling advertisement of ASPM L0s/L1 states by clearing
> corresponding bits in Link Capabilities Register through the local
> management bus, allowing ASPM to be disabled on platforms which don't
> support it.
>
> Signed-off-by: Yao Zi <me@ziyao.cc>
> Tested-by: Han Gao <gaohan@iscas.ac.cn>
> ---
>   .../controller/cadence/pcie-cadence-host.c    |  7 +++++++
>   drivers/pci/controller/cadence/pcie-cadence.h | 19 +++++++++++++++++++
>   2 files changed, 26 insertions(+)
>
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index db3154c1eccb..0bc9e6e90e0e 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -147,6 +147,13 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
>   	cdns_pcie_rp_writeb(pcie, PCI_CLASS_PROG, 0);
>   	cdns_pcie_rp_writew(pcie, PCI_CLASS_DEVICE, PCI_CLASS_BRIDGE_PCI);
>   
> +	value = cdns_pcie_rp_readl(pcie, CDNS_PCIE_RP_CAP_OFFSET + PCI_EXP_LNKCAP);
> +	if (rc->quirk_broken_aspm_l0s)
> +		value &= ~PCI_EXP_LNKCAP_ASPM_L0S;
> +	if (rc->quirk_broken_aspm_l1)
> +		value &= ~PCI_EXP_LNKCAP_ASPM_L1;
> +	cdns_pcie_rp_writel(pcie, CDNS_PCIE_RP_CAP_OFFSET + PCI_EXP_LNKCAP, value);
> +
>   	return 0;
>   }
>   
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index 443033c607d7..32a5666204f5 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -115,6 +115,8 @@ struct cdns_pcie {
>    * @quirk_detect_quiet_flag: LTSSM Detect Quiet min delay set as quirk
>    * @ecam_supported: Whether the ECAM is supported
>    * @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.
>    */
>   struct cdns_pcie_rc {
>   	struct cdns_pcie	pcie;
> @@ -127,6 +129,8 @@ struct cdns_pcie_rc {
>   	unsigned int		quirk_detect_quiet_flag:1;
>   	unsigned int            ecam_supported:1;
>   	unsigned int            no_inbound_map:1;
> +	unsigned int            quirk_broken_aspm_l0s:1;
> +	unsigned int            quirk_broken_aspm_l1:1;
>   };
>   
>   /**
> @@ -344,6 +348,21 @@ static inline u16 cdns_pcie_rp_readw(struct cdns_pcie *pcie, u32 reg)
>   	return cdns_pcie_read_sz(addr, 0x2);
>   }
>   
> +static inline void cdns_pcie_rp_writel(struct cdns_pcie *pcie,
> +				       u32 reg, u32 value)
> +{
> +	void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
> +
> +	cdns_pcie_write_sz(addr, 0x4, value);
> +}
> +
> +static inline u32 cdns_pcie_rp_readl(struct cdns_pcie *pcie, u32 reg)
> +{
> +	void __iomem *addr = pcie->reg_base + CDNS_PCIE_RP_BASE + reg;
> +
> +	return cdns_pcie_read_sz(addr, 0x4);
> +}
> +
>   static inline void cdns_pcie_hpa_rp_writeb(struct cdns_pcie *pcie,
>   					   u32 reg, u8 value)
>   {

LGTM.

Reviewed-by: Chen Wang <unicorn_wang@outlook.com>

Tested-by: Chen Wang <unicorn_wang@outlook.com> on Pioneerbox.

Thanks,

Chen