Re: [PATCH v3] PCI: cadence: Clear the ARI Capability Next Function Number of the last function

[Vignesh Raghavendra]

On 16/03/23 12:41, Achal Verma wrote:
> From: Jasko-EXT Wojciech <wojciech.jasko-EXT@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> 
> Next Function Number field in ARI Capability Register for last function
> must be zero by default as per the PCIe specification, indicating there
> is no next higher number function but that's not happening in our case,
> so this patch clears the Next Function Number field for last function used.
> 
> Signed-off-by: Jasko-EXT Wojciech <wojciech.jasko-EXT@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Achal Verma <a-verma1@xxxxxx>
> ---
> Changes from v1:
> * Fix commments in the code.
> 
> Changes from v2:
> * Rework the commit message.
> 
>  drivers/pci/controller/cadence/pcie-cadence-ep.c | 14 +++++++++++++-
>  drivers/pci/controller/cadence/pcie-cadence.h    |  6 ++++++
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> index b8b655d4047e..8742b2f594fd 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> @@ -565,7 +565,8 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
>  	struct cdns_pcie *pcie = &ep->pcie;
>  	struct device *dev = pcie->dev;
>  	int max_epfs = sizeof(epc->function_num_map) * 8;
> -	int ret, value, epf;
> +	int ret, epf, last_fn;
> +	u32 reg, value;
>  
>  	/*
>  	 * BIT(0) is hardwired to 1, hence function 0 is always enabled
> @@ -573,6 +574,17 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
>  	 */
>  	cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, epc->function_num_map);
>  
> +	/*
> +	 * Next function field in ARI_CAP_AND_CTR register for last function
> +	 * should be 0.
> +	 * Clearing Next Function Number field for the last function used.
> +	 */
> +	last_fn = find_last_bit(&epc->function_num_map, BITS_PER_LONG);
> +	reg     = CDNS_PCIE_CORE_PF_I_ARI_CAP_AND_CTRL(last_fn);
> +	value  = cdns_pcie_readl(pcie, reg);
> +	value &= ~CDNS_PCIE_ARI_CAP_NFN_MASK;
> +	cdns_pcie_writel(pcie, reg, value);
> +
>  	if (ep->quirk_disable_flr) {
>  		for (epf = 0; epf < max_epfs; epf++) {
>  			if (!(epc->function_num_map & BIT(epf)))
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index 190786e47df9..68c4c7878111 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -130,6 +130,12 @@
>  #define CDNS_PCIE_EP_FUNC_DEV_CAP_OFFSET	0xc0
>  #define CDNS_PCIE_EP_FUNC_SRIOV_CAP_OFFSET	0x200
>  
> +/*
> + * Endpoint PF Registers
> + */
> +#define CDNS_PCIE_CORE_PF_I_ARI_CAP_AND_CTRL(fn)	(0x144 + (fn) * 0x1000)
> +#define CDNS_PCIE_ARI_CAP_NFN_MASK	GENMASK(15, 8)
> +
>  /*
>   * Root Port Registers (PCI configuration space for the root port function)
>   */



Reviewed-by: Vignesh Raghavendra <vigneshr@xxxxxx>

FYI, there seems to be a duplicate patch [1], you may want to clarify
which one to look at


[1] https://lore.kernel.org/all/20230316065455.191785-1-a-verma1@xxxxxx/

-- 
Regards
Vignesh