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

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Date:   Thu, 15 Aug 2019 16:46:05 -0700
From:   Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
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 8/15/19 3:19 PM, Bjorn Helgaas wrote:
> 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.
I will move this patch to the end of this series.
>
>>   	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.
>
-- 
Sathyanarayanan Kuppuswamy
Linux kernel developer