linux-kernel - Re: [PATCH v4 3/5] ACPI/PCI: Ignore _OSC negotiation result if pcie_ports

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Date:   Fri, 29 May 2020 18:12:54 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     sathyanarayanan.kuppuswamy@...ux.intel.com
Cc:     bhelgaas@...gle.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, ashok.raj@...el.com
Subject: Re: [PATCH v4 3/5] ACPI/PCI: Ignore _OSC negotiation result if
 pcie_ports_native is set.

On Tue, May 26, 2020 at 04:18:27PM -0700, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 
> pcie_ports_native is set only if user requests native handling
> of PCIe capabilities via pcie_port_setup command line option.
> User input takes precedence over _OSC based control negotiation
> result. So consider the _OSC negotiated result only if
> pcie_ports_native is unset.
> 
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> ---
>  drivers/acpi/pci_root.c | 26 ++++++++++++++------------
>  1 file changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 9e235c1a75ff..e0039ad3480a 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -914,18 +914,20 @@ struct pci_bus *acpi_pci_root_create(struct acpi_pci_root *root,
>  		goto out_release_info;
>  
>  	host_bridge = to_pci_host_bridge(bus->bridge);
> -	if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
> -		host_bridge->native_pcie_hotplug = 0;
> -	if (!(root->osc_control_set & OSC_PCI_SHPC_NATIVE_HP_CONTROL))
> -		host_bridge->native_shpc_hotplug = 0;
> -	if (!(root->osc_control_set & OSC_PCI_EXPRESS_AER_CONTROL))
> -		host_bridge->native_aer = 0;
> -	if (!(root->osc_control_set & OSC_PCI_EXPRESS_PME_CONTROL))
> -		host_bridge->native_pme = 0;
> -	if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL))
> -		host_bridge->native_ltr = 0;
> -	if (!(root->osc_control_set & OSC_PCI_EXPRESS_DPC_CONTROL))
> -		host_bridge->native_dpc = 0;
> +	if (!pcie_ports_native) {
> +		if (!(root->osc_control_set & OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
> +			host_bridge->native_pcie_hotplug = 0;
> +		if (!(root->osc_control_set & OSC_PCI_SHPC_NATIVE_HP_CONTROL))
> +			host_bridge->native_shpc_hotplug = 0;
> +		if (!(root->osc_control_set & OSC_PCI_EXPRESS_AER_CONTROL))
> +			host_bridge->native_aer = 0;
> +		if (!(root->osc_control_set & OSC_PCI_EXPRESS_PME_CONTROL))
> +			host_bridge->native_pme = 0;
> +		if (!(root->osc_control_set & OSC_PCI_EXPRESS_LTR_CONTROL))
> +			host_bridge->native_ltr = 0;
> +		if (!(root->osc_control_set & OSC_PCI_EXPRESS_DPC_CONTROL))
> +			host_bridge->native_dpc = 0;
> +	}

I like this, but what I had in mind was to *remove* the tests of
pcie_ports_native elsewhere at the same time.

For example, 

  @@ -255,7 +255,7 @@ static bool pme_is_native(struct pcie_device *dev)
	  const struct pci_host_bridge *host;

	  host = pci_find_host_bridge(dev->port->bus);
  -       return pcie_ports_native || host->native_pme;
  +       return host->native_pme;
   }

and

  @@ -221,7 +221,7 @@ int pcie_aer_is_native(struct pci_dev *dev)
	  if (!dev->aer_cap)
		  return 0;

  -       return pcie_ports_native || host->native_aer;
  +       return host->native_aer;
   }

So I deferred these two _OSC-related things for now.  We can work on
this more in the next cycle.

>  	/*
>  	 * Evaluate the "PCI Boot Configuration" _DSM Function.  If it
> -- 
> 2.17.1
>