Re: [PATCH v3 9/9] cxl/acpi: Set ACPI's CXL _OSC to indicate CXL1.1 support

Terry Bowman
2022-11-10T19:43:36Z

On 11/9/22 17:35, Bjorn Helgaas wrote:
> On Wed, Nov 09, 2022 at 11:40:59AM +0100, Robert Richter wrote:
>> From: Terry Bowman <terry.bowman@amd.com>
>>
>> ACPI includes a CXL _OSC support procedure to communicate the available
>> CXL support to FW. The CXL support _OSC includes a field to indicate
>> CXL1.1 RCH RCD support. The OS sets this bit to 1 if it supports access
>> to RCD and RCH Port registers.[1] FW can potentially change it's operation
>
> s/it's/its/
>

Ok, will fix.

>> depending on the _OSC support setting reported by the OS.
>>
>> The ACPI driver does not currently set the ACPI _OSC support to indicate
>> CXL1.1 RCD RCH support. Change the capability reported to include CXL1.1.
>
> Eight instances of "support" above seems like it might be more than
> necessary.
>
> I don't know the history, but OSC_CXL_1_1_PORT_REG_ACCESS_SUPPORT and
> OSC_CXL_2_0_PORT_DEV_REG_ACCESS_SUPPORT seem like sort of weird names
> since they don't match the spec at all ("RCD and RCH Port Register
> Access Supported" and "CXL VH Register Access Supported").
>

I'll reword to not excessively reuse 'support'. Thanks for point out.

Regards,
Terry

>> [1] CXL3.0 Table 9-26 'Interpretation of CXL _OSC Support Field'
>>
>> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
>> Signed-off-by: Robert Richter <rrichter@amd.com>
>> ---
>> drivers/acpi/pci_root.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index c8385ef54c37..094a59b216ae 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -492,6 +492,7 @@ static u32 calculate_cxl_support(void)
>> u32 support;
>>
>> support = OSC_CXL_2_0_PORT_DEV_REG_ACCESS_SUPPORT;
>> + support |= OSC_CXL_1_1_PORT_REG_ACCESS_SUPPORT;
>> if (pci_aer_available())
>> support |= OSC_CXL_PROTOCOL_ERR_REPORTING_SUPPORT;
>> if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
>> --
>> 2.30.2
>>