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

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Date:   Fri, 17 Mar 2023 09:57:48 +0530
From:   "Verma, Achal" <a-verma1@...com>
To:     Vignesh Raghavendra <vigneshr@...com>,
        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>
CC:     <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>,
        <wojciech.jasko-EXT@...tinental-corporation.com>
Subject: Re: [PATCH v3] PCI: cadence: Clear the ARI Capability Next Function
 Number of the last function



On 3/17/2023 9:38 AM, Vignesh Raghavendra wrote:
> 
> 
> On 16/03/23 12:41, Achal Verma wrote:
>> From: Jasko-EXT Wojciech <wojciech.jasko-EXT@...tinental-corporation.com>
>>
>> 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@...tinental-corporation.com>
>> Signed-off-by: Achal Verma <a-verma1@...com>
>> ---
>> 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@...com>
> 
> 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@ti.com/
Please consider this one.

Thanks,
Achal Verma
>