linux-kernel - Re: [PATCH INTERNAL 3/3] PCI: iproc: Disable MSI parsing in certain PAXC blocks

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Date:   Fri, 18 May 2018 14:53:41 +0530
From:   poza@...eaurora.org
To:     Ray Jui <ray.jui@...adcom.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com, linux-pci@...r.kernel.org,
        linux-pci-owner@...r.kernel.org
Subject: Re: [PATCH INTERNAL 3/3] PCI: iproc: Disable MSI parsing in certain
 PAXC blocks

On 2018-05-17 22:51, Ray Jui wrote:
> The internal MSI parsing logic in certain revisions of PAXC root
> complexes does not work properly and can casue corruptions on the
> writes. They need to be disabled
> 
> Signed-off-by: Ray Jui <ray.jui@...adcom.com>
> Reviewed-by: Scott Branden <scott.branden@...adcom.com>
> ---
>  drivers/pci/host/pcie-iproc.c | 34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/host/pcie-iproc.c 
> b/drivers/pci/host/pcie-iproc.c
> index 3c76c5f..b906d80 100644
> --- a/drivers/pci/host/pcie-iproc.c
> +++ b/drivers/pci/host/pcie-iproc.c
> @@ -1144,10 +1144,22 @@ static int iproc_pcie_paxb_v2_msi_steer(struct
> iproc_pcie *pcie, u64 msi_addr)
>  	return ret;
>  }
> 
> -static void iproc_pcie_paxc_v2_msi_steer(struct iproc_pcie *pcie, u64 
> msi_addr)
> +static void iproc_pcie_paxc_v2_msi_steer(struct iproc_pcie *pcie, u64 
> msi_addr,
> +					 bool enable)
>  {
>  	u32 val;
> 
> +	if (!enable) {
> +		/*
> +		 * Disable PAXC MSI steering. All write transfers will be
> +		 * treated as non-MSI transfers
> +		 */
> +		val = iproc_pcie_read_reg(pcie, IPROC_PCIE_MSI_EN_CFG);
> +		val &= ~MSI_ENABLE_CFG;
> +		iproc_pcie_write_reg(pcie, IPROC_PCIE_MSI_EN_CFG, val);
> +		return;
> +	}
> +
>  	/*
>  	 * Program bits [43:13] of address of GITS_TRANSLATER register into
>  	 * bits [30:0] of the MSI base address register.  In fact, in all 
> iProc
> @@ -1201,7 +1213,7 @@ static int iproc_pcie_msi_steer(struct iproc_pcie 
> *pcie,
>  			return ret;
>  		break;
>  	case IPROC_PCIE_PAXC_V2:
> -		iproc_pcie_paxc_v2_msi_steer(pcie, msi_addr);
> +		iproc_pcie_paxc_v2_msi_steer(pcie, msi_addr, true);

Are you calling iproc_pcie_paxc_v2_msi_steer() anywhere else with 
'false' ?
I see its getting called only from one place in current code 
iproc_pcie_msi_steer().

>  		break;
>  	default:
>  		return -EINVAL;
> @@ -1427,6 +1439,24 @@ int iproc_pcie_remove(struct iproc_pcie *pcie)
>  }
>  EXPORT_SYMBOL(iproc_pcie_remove);
> 
> +/*
> + * The MSI parsing logic in certain revisions of Broadcom PAXC based 
> root
> + * complex does not work and needs to be disabled
> + */
> +static void quirk_paxc_disable_msi_parsing(struct pci_dev *pdev)
> +{
> +	struct iproc_pcie *pcie = iproc_data(pdev->bus);
> +
> +	if (pdev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
> +		iproc_pcie_paxc_v2_msi_steer(pcie, 0, false);
> +}
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0x16f0,
> +			quirk_paxc_disable_msi_parsing);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0xd802,
> +			quirk_paxc_disable_msi_parsing);
> +DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_BROADCOM, 0xd804,
> +			quirk_paxc_disable_msi_parsing);
> +
>  MODULE_AUTHOR("Ray Jui <rjui@...adcom.com>");
>  MODULE_DESCRIPTION("Broadcom iPROC PCIe common driver");
>  MODULE_LICENSE("GPL v2");