linux-kernel - Re: [PATCH v6 3/9] PCI/ACPI: Expose EDR support via

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Message-ID: <20190815221934.GK253360@google.com>
Date:   Thu, 15 Aug 2019 17:19:34 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     sathyanarayanan.kuppuswamy@...ux.intel.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        ashok.raj@...el.com, keith.busch@...el.com,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v6 3/9] PCI/ACPI: Expose EDR support via _OSC to BIOS

On Fri, Jul 26, 2019 at 02:43:13PM -0700, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 
> As per PCI firmware specification r3.2 Downstream Port Containment
> Related Enhancements ECN, sec 4.5.1, table 4-4, if OS supports EDR,
> it should expose its support to BIOS by setting bit 7 of _OSC Support
> Field.
> 
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Len Brown <lenb@...nel.org>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> ---
>  drivers/acpi/pci_root.c | 3 +++
>  include/linux/acpi.h    | 1 +
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> index 73b08f40b0da..988d09d788b6 100644
> --- a/drivers/acpi/pci_root.c
> +++ b/drivers/acpi/pci_root.c
> @@ -132,6 +132,7 @@ static struct pci_osc_bit_struct pci_osc_support_bit[] = {
>  	{ OSC_PCI_CLOCK_PM_SUPPORT, "ClockPM" },
>  	{ OSC_PCI_SEGMENT_GROUPS_SUPPORT, "Segments" },
>  	{ OSC_PCI_MSI_SUPPORT, "MSI" },
> +	{ OSC_PCI_EDR_SUPPORT, "EDR" },
>  	{ OSC_PCI_HPX_TYPE_3_SUPPORT, "HPX-Type3" },
>  };
>  
> @@ -442,6 +443,8 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm,
>  		support |= OSC_PCI_ASPM_SUPPORT | OSC_PCI_CLOCK_PM_SUPPORT;
>  	if (pci_msi_enabled())
>  		support |= OSC_PCI_MSI_SUPPORT;
> +	if (IS_ENABLED(CONFIG_PCIE_EDR))
> +		support |= OSC_PCI_EDR_SUPPORT;

Do we really support it here?  This is patch [3/9] and it looks like
patch [6/9] might be where EDR support really gets added.  It's good
to split changes into small pieces, but only if each piece is
logically self-contained.

>  	decode_osc_support(root, "OS supports", support);
>  	status = acpi_pci_osc_support(root, support);
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 8959ed322e15..b6b43da85d26 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -515,6 +515,7 @@ extern bool osc_pc_lpi_support_confirmed;
>  #define OSC_PCI_CLOCK_PM_SUPPORT		0x00000004
>  #define OSC_PCI_SEGMENT_GROUPS_SUPPORT		0x00000008
>  #define OSC_PCI_MSI_SUPPORT			0x00000010
> +#define OSC_PCI_EDR_SUPPORT			0x00000080
>  #define OSC_PCI_HPX_TYPE_3_SUPPORT		0x00000100
>  #define OSC_PCI_SUPPORT_MASKS			0x0000011f

You defined a new bit above but didn't update OSC_PCI_SUPPORT_MASKS to
include that bit.  This looks broken.