[PATCH 01/13] PCI: dwc/imx6: Drop setting PCI_MSI_FLAGS_ENABLE

[Michael Ellerman]

Rob Herring <robh at kernel.org> writes:
> No other host driver sets the PCI_MSI_FLAGS_ENABLE bit, so it must not
> be necessary. If it is, a comment is needed.

Yeah, but git blame directly points to:

  75cb8d20c112 ("PCI: imx: Enable MSI from downstream components")

Which has a pretty long explanation. The relevant bit probably being:

  ... on i.MX6, the MSI Enable bit controls delivery of MSI interrupts
  from components below the Root Port.


So it seems a little rash to just remove the code.

cheers


> Cc: Richard Zhu <hongxing.zhu at nxp.com>
> Cc: Lucas Stach <l.stach at pengutronix.de>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Cc: Bjorn Helgaas <bhelgaas at google.com>
> Cc: Shawn Guo <shawnguo at kernel.org>
> Cc: Sascha Hauer <s.hauer at pengutronix.de>
> Cc: Pengutronix Kernel Team <kernel at pengutronix.de>
> Cc: Fabio Estevam <festevam at gmail.com>
> Cc: NXP Linux Team <linux-imx at nxp.com>
> Signed-off-by: Rob Herring <robh at kernel.org>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 8 --------
>  1 file changed, 8 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 5cf1ef12fb9b..7dd137d62dca 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -1002,7 +1002,6 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  	struct resource *dbi_base;
>  	struct device_node *node = dev->of_node;
>  	int ret;
> -	u16 val;
>  
>  	imx6_pcie = devm_kzalloc(dev, sizeof(*imx6_pcie), GFP_KERNEL);
>  	if (!imx6_pcie)
> @@ -1167,13 +1166,6 @@ static int imx6_pcie_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (pci_msi_enabled()) {
> -		u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
> -		val = dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
> -		val |= PCI_MSI_FLAGS_ENABLE;
> -		dw_pcie_writew_dbi(pci, offset + PCI_MSI_FLAGS, val);
> -	}
> -
>  	return 0;
>  }
>  
> -- 
> 2.25.1