drm/amdgpu: return the PCIe gen and lanes from the INFO ioctl

For computing PCIe bandwidth in userspace and troubleshooting PCIe
bandwidth issues. Note that this intentionally fills holes and padding
in drm_amdgpu_info_device.

Mesa MR: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20790

Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Marek Olšák

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

@@ -107,9 +107,10 @@
  * - 3.49.0 - Add gang submit into CS IOCTL
  * - 3.50.0 - Update AMDGPU_INFO_DEV_INFO IOCTL for minimum engine and memory clock
  *            Update AMDGPU_INFO_SENSOR IOCTL for PEAK_PSTATE engine and memory clock
+ *   3.51.0 - Return the PCIe gen and lanes from the INFO ioctl
  */
 #define KMS_DRIVER_MAJOR	3
-#define KMS_DRIVER_MINOR	50
+#define KMS_DRIVER_MINOR	51
 #define KMS_DRIVER_PATCHLEVEL	0
 
 unsigned int amdgpu_vram_limit = UINT_MAX;

drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

@@ -43,6 +43,7 @@
 #include "amdgpu_gem.h"
 #include "amdgpu_display.h"
 #include "amdgpu_ras.h"
+#include "amd_pcie.h"
 
 void amdgpu_unregister_gpu_instance(struct amdgpu_device *adev)
 {
@@ -767,6 +768,7 @@ int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 	case AMDGPU_INFO_DEV_INFO: {
 		struct drm_amdgpu_info_device *dev_info;
 		uint64_t vm_size;
+		uint32_t pcie_gen_mask;
 		int ret;
 
 		dev_info = kzalloc(sizeof(*dev_info), GFP_KERNEL);
@@ -799,7 +801,6 @@ int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 		dev_info->num_rb_pipes = adev->gfx.config.max_backends_per_se *
 			adev->gfx.config.max_shader_engines;
 		dev_info->num_hw_gfx_contexts = adev->gfx.config.max_hw_contexts;
-		dev_info->_pad = 0;
 		dev_info->ids_flags = 0;
 		if (adev->flags & AMD_IS_APU)
 			dev_info->ids_flags |= AMDGPU_IDS_FLAGS_FUSION;
@@ -853,6 +854,17 @@ int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 
 		dev_info->tcc_disabled_mask = adev->gfx.config.tcc_disabled_mask;
 
+		/* Combine the chip gen mask with the platform (CPU/mobo) mask. */
+		pcie_gen_mask = adev->pm.pcie_gen_mask & (adev->pm.pcie_gen_mask >> 16);
+		dev_info->pcie_gen = fls(pcie_gen_mask);
+		dev_info->pcie_num_lanes =
+			adev->pm.pcie_mlw_mask & CAIL_PCIE_LINK_WIDTH_SUPPORT_X32 ? 32 :
+			adev->pm.pcie_mlw_mask & CAIL_PCIE_LINK_WIDTH_SUPPORT_X16 ? 16 :
+			adev->pm.pcie_mlw_mask & CAIL_PCIE_LINK_WIDTH_SUPPORT_X12 ? 12 :
+			adev->pm.pcie_mlw_mask & CAIL_PCIE_LINK_WIDTH_SUPPORT_X8 ? 8 :
+			adev->pm.pcie_mlw_mask & CAIL_PCIE_LINK_WIDTH_SUPPORT_X4 ? 4 :
+			adev->pm.pcie_mlw_mask & CAIL_PCIE_LINK_WIDTH_SUPPORT_X2 ? 2 : 1;
+
 		ret = copy_to_user(out, dev_info,
 				   min((size_t)size, sizeof(*dev_info))) ? -EFAULT : 0;
 		kfree(dev_info);

include/uapi/drm/amdgpu_drm.h

@@ -1053,7 +1053,8 @@ struct drm_amdgpu_info_device {
 	__u32 enabled_rb_pipes_mask;
 	__u32 num_rb_pipes;
 	__u32 num_hw_gfx_contexts;
-	__u32 _pad;
+	/* PCIe version (the smaller of the GPU and the CPU/motherboard) */
+	__u32 pcie_gen;
 	__u64 ids_flags;
 	/** Starting virtual address for UMDs. */
 	__u64 virtual_address_offset;
@@ -1100,7 +1101,8 @@ struct drm_amdgpu_info_device {
 	__u32 gs_prim_buffer_depth;
 	/* max gs wavefront per vgt*/
 	__u32 max_gs_waves_per_vgt;
-	__u32 _pad1;
+	/* PCIe number of lanes (the smaller of the GPU and the CPU/motherboard) */
+	__u32 pcie_num_lanes;
 	/* always on cu bitmap */
 	__u32 cu_ao_bitmap[4][4];
 	/** Starting high virtual address for UMDs. */