linux-kernel - Re: [PATCH] PCI: cadence: Fix next function value in case of ARI

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Date:   Wed, 18 Jan 2023 14:36:03 +0530
From:   Siddharth Vadapalli <s-vadapalli@...com>
To:     Achal Verma <a-verma1@...com>
CC:     Tom Joseph <tjoseph@...ence.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczy_ski <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Milind Parab <mparab@...ence.com>,
        Jian Wang <jian-wang@...com>, <s-vadapalli@...com>
Subject: Re: [PATCH] PCI: cadence: Fix next function value in case of ARI

Hello Achal,

On 18/01/23 12:50, Achal Verma wrote:
> From: Jasko-EXT Wojciech <wojciech.jasko-EXT@...tinental-corporation.com>
> 
> Next function field in ARI_CAP_AND_CTR field register for last
> function should be zero but thats not the case, so this patch
> programs the next function field for last function as zero.
> 
> Signed-off-by: Jasko-EXT Wojciech <wojciech.jasko-EXT@...tinental-corporation.com>
> Signed-off-by: Achal Verma <a-verma1@...com>
> ---
>  drivers/pci/controller/cadence/pcie-cadence-ep.c | 15 ++++++++++++++-
>  drivers/pci/controller/cadence/pcie-cadence.h    |  6 ++++++
>  2 files changed, 20 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..6b6904cf0123 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 +574,18 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
>  	 */
>  	cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, epc->function_num_map);
>  
> +	/* Setup ARI Next Function Number.

Please follow the standard multi-line commenting style with the first line being
"/*" followed by the comment on the next line.

> +	 * This field should point to the next physical Function and 0 for
> +	 * last Function.
> +	 */
> +	last_fn = find_last_bit(&epc->function_num_map, BITS_PER_LONG);
> +	reg     = CDNS_PCIE_CORE_PF_I_ARI_CAP_AND_CTRL(last_fn);
> +
> +	// Clear Next Function Number for the last function used.

Please enclose the comment within /* and */.

Regards,
Siddharth.