diff mbox series

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

Message ID 20201028204646.356535-2-robh@kernel.org
State Not Applicable
Headers show
Series PCI: dwc: Another round of clean-ups | expand

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Context Check Description
snowpatch_ozlabs/needsstable success Patch has no Fixes tags
snowpatch_ozlabs/checkpatch success
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (8cb17737940b156329cb5210669b9c9b23f4dd56)

Commit Message

Rob Herring Oct. 28, 2020, 8:46 p.m. UTC
No other host driver sets the PCI_MSI_FLAGS_ENABLE bit, so it must not
be necessary. If it is, a comment is needed.

Cc: Richard Zhu <hongxing.zhu@nxp.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Signed-off-by: Rob Herring <robh@kernel.org>
---
 drivers/pci/controller/dwc/pci-imx6.c | 8 --------
 1 file changed, 8 deletions(-)

Comments

Michael Ellerman Oct. 29, 2020, 12:21 a.m. UTC | #1
Rob Herring <robh@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@nxp.com>
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Signed-off-by: Rob Herring <robh@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
Rob Herring Oct. 29, 2020, 1:01 p.m. UTC | #2
On Wed, Oct 28, 2020 at 7:21 PM Michael Ellerman <mpe@ellerman.id.au> wrote:
>
> Rob Herring <robh@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")

I think I did read this at some point and then forgot about it when I
made the change later...

> 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.

The thing is that all seems not i.MX6 specific but DWC specific given
MSI handling is contained within the DWC block. So I don't see how
this could be an integration difference.

So maybe everyone else is still just setting CONFIG_PCIEPORTBUS
typically and haven't noticed? Is it correct for the host driver to
set MSI enable?

Rob
diff mbox series

Patch

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;
 }