Re: [PATCH] drm/amd: Add a sysfs file to detect whether a GPU is an APU

[Mario Limonciello]

On 6/16/25 9:53 PM, Alex Deucher wrote:

On Mon, Jun 16, 2025 at 4:21 PM Mario Limonciello <supe...@kernel.org> wrote:

From: Mario Limonciello <mario.limoncie...@amd.com>

In order to discover whether a GPU is part of a dGPU or APU userspace has
to do some mental gymnastics or heuristics.  Add a sysfs file that clearly
indicates to userspace.

You can already query this via the INFO IOCTL.  What use case did you
have in mind for this interface?

You're right; the IOCTL is totally fine for this.  Disregard the patch.

Thanks,>

Alex

Signed-off-by: Mario Limonciello <mario.limoncie...@amd.com>
---
  drivers/gpu/drm/amd/pm/amdgpu_pm.c     | 16 ++++++++++++++++
  drivers/gpu/drm/amd/pm/inc/amdgpu_pm.h |  1 +
  2 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/amd/pm/amdgpu_pm.c 
b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
index edd9895b46c02..4e4c77488e334 100644
--- a/drivers/gpu/drm/amd/pm/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
@@ -945,6 +945,21 @@ static ssize_t amdgpu_get_pp_features(struct device *dev,
         return size;
  }

+/**
+ * DOC: apu
+ *
+ * Represents whether GPU is on a dGPU (0) or APU (1)
+ */
+static ssize_t amdgpu_get_apu(struct device *dev,
+                             struct device_attribute *attr,
+                             char *buf)
+{
+       struct drm_device *ddev = dev_get_drvdata(dev);
+       struct amdgpu_device *adev = drm_to_adev(ddev);
+
+       return sysfs_emit(buf, "%d\n", adev->flags & AMD_IS_APU ? 1 : 0);
+}
+
  /**
   * DOC: pp_dpm_sclk pp_dpm_mclk pp_dpm_socclk pp_dpm_fclk pp_dpm_dcefclk 
pp_dpm_pcie
   *
@@ -2287,6 +2302,7 @@ static struct amdgpu_device_attr amdgpu_device_attrs[] = {
                               .attr_update = ss_bias_attr_update),
         AMDGPU_DEVICE_ATTR_RO(pm_metrics,                               
ATTR_FLAG_BASIC,
                               .attr_update = amdgpu_pm_metrics_attr_update),
+       AMDGPU_DEVICE_ATTR_RO(apu,                                      
ATTR_FLAG_BASIC),
  };

  static int default_attr_update(struct amdgpu_device *adev, struct 
amdgpu_device_attr *attr,
diff --git a/drivers/gpu/drm/amd/pm/inc/amdgpu_pm.h 
b/drivers/gpu/drm/amd/pm/inc/amdgpu_pm.h
index c12ced32f7808..ffd008c1e6ec2 100644
--- a/drivers/gpu/drm/amd/pm/inc/amdgpu_pm.h
+++ b/drivers/gpu/drm/amd/pm/inc/amdgpu_pm.h
@@ -78,6 +78,7 @@ enum amdgpu_device_attr_id {
         device_attr_id__smartshift_dgpu_power,
         device_attr_id__smartshift_bias,
         device_attr_id__pm_metrics,
+       device_attr_id__apu,
         device_attr_id__count,
  };

--
2.43.0