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

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Date:   Wed, 26 Jan 2022 13:10:03 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     bhelgaas@...gle.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 2/2] PCI/DPC: Disable DPC when link is in L2/L3 ready, L2
 and L3 state

Hi,

On Wed, Jan 26, 2022 at 03:18:52PM +0800, Kai-Heng Feng wrote:
> Since TLP and DLLP transmission is disabled for a Link in L2/L3 Ready,
> L2 and L3, and DPC depends on AER, so also disable DPC here.

Here too I think it is good to mention that the DPC "service" never
implemented the PM hooks in the first place

> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>

One minor comment below, but other than that looks good,

Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

> ---
>  drivers/pci/pcie/dpc.c | 61 +++++++++++++++++++++++++++++++-----------
>  1 file changed, 45 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 3e9afee02e8d1..9585c10b7c577 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -343,13 +343,34 @@ 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);
> +

Drop the empty line here.

> +	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);
> +}