[PATCH 2/4] drm/amdgpu: Add xgmi speed/width related info

[Kim, Jonathan]

[Public]

> -----Original Message-----
> From: Lazar, Lijo <Lijo.Lazar at amd.com>
> Sent: Thursday, February 6, 2025 8:13 AM
> To: amd-gfx at lists.freedesktop.org; Lazar, Lijo <Lijo.Lazar at amd.com>
> Cc: Zhang, Hawking <Hawking.Zhang at amd.com>; Kim, Jonathan
> <Jonathan.Kim at amd.com>
> Subject: [PATCH 2/4] drm/amdgpu: Add xgmi speed/width related info
>
> Add APIs to initialize XGMI speed, width details and get to max
> bandwidth supported. It is assumed that a device only supports same
> generation of XGMI links with uniform width.
>
> Signed-off-by: Lijo Lazar <lijo.lazar at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c | 41 ++++++++++++++++++++++++
>  drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h | 11 +++++++
>  2 files changed, 52 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> index 03d909c7b14b..edef5763e2b8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> @@ -1679,3 +1679,44 @@ bool amdgpu_xgmi_same_hive(struct amdgpu_device
> *adev,
>               adev->gmc.xgmi.hive_id &&
>               adev->gmc.xgmi.hive_id == bo_adev->gmc.xgmi.hive_id);
>  }
> +
> +static inline uint32_t
> +__amdgpu_xgmi_get_max_bandwidth(uint8_t link_width,
> +                             enum amdgpu_xgmi_link_speed max_speed)
> +{
> +     /* Returns unidirectional bandwidth in Mbps */
> +     return max_speed * 1000 * link_width;

Instead of wrapping this in a new static, would it work to declare a new member adev->gmc.xgmi.max_bandwidth?
Then in amdgpu_xgmi_init_info, you can define max_bandwidth directly after the switch.

> +}
> +
> +/**
> + * amdgpu_xgmi_get_max_bandwidth - Get max possible bandwidth of a single
> XGMI
> + * link of the device in Mbps
> + * @adev: Target device.
> + *
> + * Gets the max possible bandwidth of a single XGMI link of the device in Mbps.
> + * Assumption is all links of the device have the same width and are of the
> + * same XGMI generation.
> + */
> +uint32_t amdgpu_xgmi_get_max_bandwidth(struct amdgpu_device *adev)
> +{
> +     if (!adev->gmc.xgmi.supported)
> +             return 0;
> +
> +     return __amdgpu_xgmi_get_max_bandwidth(adev->gmc.xgmi.max_width,
> adev->gmc.xgmi.max_speed);

If you do the suggested above, both tests can be simplified into 1 line as
-> return = xgmi_supported ? max_bandwidth : 0;

> +}
> +
> +void amdgpu_xgmi_init_info(struct amdgpu_device *adev)
> +{
> +     switch (amdgpu_ip_version(adev, XGMI_HWIP, 0)) {
> +     case IP_VERSION(6, 1, 0):
> +             adev->gmc.xgmi.max_speed = XGMI2_5_SPEED_GT;
> +             adev->gmc.xgmi.max_width = 16;
> +             break;
> +     case IP_VERSION(6, 4, 0):
> +             adev->gmc.xgmi.max_speed = XGMI3_SPEED_GT;
> +             adev->gmc.xgmi.max_width = 16;
> +             break;
> +     default:
> +             break;
> +     }
> +}
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> index 044c4f6be44a..384c4ddef78a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h
> @@ -25,6 +25,12 @@
>  #include <drm/task_barrier.h>
>  #include "amdgpu_ras.h"
>
> +enum amdgpu_xgmi_link_speed {
> +     XGMI2_SPEED_GT = 16,
> +     XGMI2_5_SPEED_GT = 25,
> +     XGMI3_SPEED_GT = 32

Why not declare and define them as units of Mbps to begin with so you don't have to do the calculation later?

Jon

> +};
> +
>  struct amdgpu_hive_info {
>       struct kobject kobj;
>       uint64_t hive_id;
> @@ -75,6 +81,8 @@ struct amdgpu_xgmi {
>       struct ras_common_if *ras_if;
>       bool connected_to_cpu;
>       struct amdgpu_xgmi_ras *ras;
> +     enum amdgpu_xgmi_link_speed max_speed;
> +     uint8_t max_width;
>  };
>
>  struct amdgpu_hive_info *amdgpu_get_xgmi_hive(struct amdgpu_device *adev);
> @@ -102,4 +110,7 @@ int amdgpu_xgmi_request_nps_change(struct
> amdgpu_device *adev,
>  int amdgpu_get_xgmi_link_status(struct amdgpu_device *adev,
>                               int global_link_num);
>
> +void amdgpu_xgmi_init_info(struct amdgpu_device *adev);
> +uint32_t amdgpu_xgmi_get_max_bandwidth(struct amdgpu_device *adev);
> +
>  #endif
> --
> 2.25.1