linux-kernel - Re: [PATCH v2 2/2] PCI/DPC: Disable DPC service when link is in L2/L3 ready, L2 and L3 state

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Message-ID: <aa810b71-89b2-f18e-5564-d65ed421b8d9@linux.intel.com>
Date:   Sat, 19 Mar 2022 13:40:20 -0700
From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>, bhelgaas@...gle.com
Cc:     mika.westerberg@...ux.intel.com, koba.ko@...onical.com,
        Russell Currey <ruscur@...sell.cc>,
        Oliver O'Halloran <oohall@...il.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] PCI/DPC: Disable DPC service when link is in L2/L3
 ready, L2 and L3 state



On 1/26/22 6:54 PM, Kai-Heng Feng wrote:
> Since TLP and DLLP transmission is disabled for a Link in L2/L3 Ready,
> L2 and L3 (i.e. device in D3hot and D3cold), and DPC depends on AER, so

Better description about the problem would be helpful. I know you
have included a log in AER patch. But a quick summary of the problem
in this patch will make it easier to read the patch.

> also disable DPC here.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v2:
>   - Wording change.
>   - Empty line dropped.
> 
>   drivers/pci/pcie/dpc.c | 60 +++++++++++++++++++++++++++++++-----------
>   1 file changed, 44 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 3e9afee02e8d1..414258967f08e 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -343,13 +343,33 @@ void pci_dpc_init(struct pci_dev *pdev)
>   	}
>   }
>   
> +static void dpc_enable(struct pcie_device *dev)
> +{
> +	struct pci_dev *pdev = dev->port;
> +	u16 ctl;
> +
> +	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, &ctl);
> +	ctl = (ctl & 0xfff4) | PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN;
> +	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, ctl);
> +}
> +
> +static void dpc_disable(struct pcie_device *dev)
> +{
> +	struct pci_dev *pdev = dev->port;
> +	u16 ctl;
> +
> +	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, &ctl);
> +	ctl &= ~(PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN);
> +	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, ctl);
> +}
> +
>   #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
>   static int dpc_probe(struct pcie_device *dev)
>   {
>   	struct pci_dev *pdev = dev->port;
>   	struct device *device = &dev->device;
>   	int status;
> -	u16 ctl, cap;
> +	u16 cap;
>   
>   	if (!pcie_aer_is_native(pdev) && !pcie_ports_dpc_native)
>   		return -ENOTSUPP;
> @@ -364,10 +384,7 @@ static int dpc_probe(struct pcie_device *dev)
>   	}
>   
>   	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CAP, &cap);
> -	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, &ctl);
> -
> -	ctl = (ctl & 0xfff4) | PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN;
> -	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, ctl);
> +	dpc_enable(dev);
>   	pci_info(pdev, "enabled with IRQ %d\n", dev->irq);
>   
>   	pci_info(pdev, "error containment capabilities: Int Msg #%d, RPExt%c PoisonedTLP%c SwTrigger%c RP PIO Log %d, DL_ActiveErr%c\n",
> @@ -380,22 +397,33 @@ static int dpc_probe(struct pcie_device *dev)
>   	return status;
>   }
>   
> -static void dpc_remove(struct pcie_device *dev)
> +static int dpc_suspend(struct pcie_device *dev)
>   {
> -	struct pci_dev *pdev = dev->port;
> -	u16 ctl;
> +	dpc_disable(dev);
> +	return 0;
> +}
>   
> -	pci_read_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, &ctl);
> -	ctl &= ~(PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN);
> -	pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_CTL, ctl);
> +static int dpc_resume(struct pcie_device *dev)
> +{
> +	dpc_enable(dev);
> +	return 0;
> +}
> +
> +static void dpc_remove(struct pcie_device *dev)
> +{
> +	dpc_disable(dev);
>   }
>   
>   static struct pcie_port_service_driver dpcdriver = {
> -	.name		= "dpc",
> -	.port_type	= PCIE_ANY_PORT,
> -	.service	= PCIE_PORT_SERVICE_DPC,
> -	.probe		= dpc_probe,
> -	.remove		= dpc_remove,
> +	.name			= "dpc",
> +	.port_type		= PCIE_ANY_PORT,
> +	.service		= PCIE_PORT_SERVICE_DPC,
> +	.probe			= dpc_probe,
> +	.suspend		= dpc_suspend,
> +	.resume			= dpc_resume,
> +	.runtime_suspend	= dpc_suspend,
> +	.runtime_resume		= dpc_resume,
> +	.remove			= dpc_remove,
>   };
>   
>   int __init pcie_dpc_init(void)

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer