Re: [PATCH V2 6/9] PCI/TPH: Retrieve steering tag from ACPI _DSM

Simon Horman
2024-06-04T15:30:34Z

On Fri, May 31, 2024 at 04:38:38PM -0500, Wei Huang wrote:
> According to PCI SIG ECN, calling the _DSM firmware method for a given
> CPU_UID returns the steering tags for different types of memory
> (volatile, non-volatile). These tags are supposed to be used in ST
> table entry for optimal results.
>
> Co-developed-by: Eric Van Tassell <Eric.VanTassell@amd.com>
> Signed-off-by: Eric Van Tassell <Eric.VanTassell@amd.com>
> Signed-off-by: Wei Huang <wei.huang2@amd.com>
> Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
> Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
> Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>

...

> diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c

...

> +static bool invoke_dsm(acpi_handle handle, u32 cpu_uid, u8 ph,
> + u8 target_type, bool cache_ref_valid,
> + u64 cache_ref, union st_info *st_out)
> +{
> + union acpi_object in_obj, in_buf[3], *out_obj;
> +
> + in_buf[0].integer.type = ACPI_TYPE_INTEGER;
> + in_buf[0].integer.value = 0; /* 0 => processor cache steering tags */
> +
> + in_buf[1].integer.type = ACPI_TYPE_INTEGER;
> + in_buf[1].integer.value = cpu_uid;
> +
> + in_buf[2].integer.type = ACPI_TYPE_INTEGER;
> + in_buf[2].integer.value = ph & 3;
> + in_buf[2].integer.value |= (target_type & 1) << 2;
> + in_buf[2].integer.value |= (cache_ref_valid & 1) << 3;
> + in_buf[2].integer.value |= (cache_ref << 32);
> +
> + in_obj.type = ACPI_TYPE_PACKAGE;
> + in_obj.package.count = ARRAY_SIZE(in_buf);
> + in_obj.package.elements = in_buf;
> +
> + out_obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, MIN_ST_DSM_REV,
> + ST_DSM_FUNC_INDEX, &in_obj);

Hi Wei Huang, Eric, all,

This seems to break builds on ARM (32bit) with multi_v7_defconfig.

.../tph.c:221:39: error: use of undeclared identifier 'pci_acpi_dsm_guid'
221 | out_obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, MIN_ST_DSM_REV,
|

I suspect a dependency on ACPI in Kconfig is appropriate.

> +
> + if (!out_obj)
> + return false;
> +
> + if (out_obj->type != ACPI_TYPE_BUFFER) {
> + pr_err("invalid return type %d from TPH _DSM\n",
> + out_obj->type);
> + ACPI_FREE(out_obj);
> + return false;
> + }

...