[PATCH 2/2] drm/amdgpu: Add debugfs interface to set arbitrary sclk for navi14

[Quan, Evan]

Please add proper lock in smu_set_soft_freq_range() then.
You can do necessary modification to existing code paths.
Otherwise without lock protection, you may run into race condition on the new debugfs intrace(amdgpu_debugfs_sclk_set) called by multiple instances.

-----Original Message-----
From: Gui, Jack <Jack.Gui at amd.com> 
Sent: Friday, February 28, 2020 12:35 PM
To: Quan, Evan <Evan.Quan at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Feng, Kenneth <Kenneth.Feng at amd.com>; Xu, Feifei <Feifei.Xu at amd.com>
Subject: RE: [PATCH 2/2] drm/amdgpu: Add debugfs interface to set arbitrary sclk for navi14

[AMD Official Use Only - Internal Distribution Only]

Hi Evan,

No lock is created for smu_set_soft_freq_range() in this code path.
But some other sysfs interfaces calling  smu_set_soft_freq_range() indirectly have created lock in middle function to protect  smu_set_soft_freq_range() as critical resource.
So, if we want to lock the "issue message action" in smu_set_soft_freq_range(), another patch is needed.

BR,
Jack

-----Original Message-----
From: Quan, Evan <Evan.Quan at amd.com>
Sent: Friday, February 28, 2020 11:37 AM
To: Gui, Jack <Jack.Gui at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Feng, Kenneth <Kenneth.Feng at amd.com>; Xu, Feifei <Feifei.Xu at amd.com>; Gui, Jack <Jack.Gui at amd.com>
Subject: RE: [PATCH 2/2] drm/amdgpu: Add debugfs interface to set arbitrary sclk for navi14

Please confirm whether smu_set_soft_freq_range() is properly lock protected.

-----Original Message-----
From: Chengming Gui <Jack.Gui at amd.com>
Sent: Friday, February 28, 2020 10:37 AM
To: amd-gfx at lists.freedesktop.org
Cc: Quan, Evan <Evan.Quan at amd.com>; Feng, Kenneth <Kenneth.Feng at amd.com>; Xu, Feifei <Feifei.Xu at amd.com>; Gui, Jack <Jack.Gui at amd.com>
Subject: [PATCH 2/2] drm/amdgpu: Add debugfs interface to set arbitrary sclk for navi14

add debugfs interface amdgpu_force_sclk
to set arbitrary sclk for navi14

Signed-off-by: Chengming Gui <Jack.Gui at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c    | 44 ++++++++++++++++++++++++++
 drivers/gpu/drm/amd/powerplay/inc/amdgpu_smu.h |  3 ++
 2 files changed, 47 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index 3bb7405..5ee7e92 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -1269,9 +1269,43 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
 	return 0;
 }
 
+static int amdgpu_debugfs_sclk_set(void *data, u64 val) {
+	int ret = 0;
+	uint32_t max_freq, min_freq;
+	struct amdgpu_device *adev = (struct amdgpu_device *)data;
+
+	if (amdgpu_sriov_vf(adev) && !amdgpu_sriov_is_pp_one_vf(adev))
+		return -EINVAL;
+
+	ret = pm_runtime_get_sync(adev->ddev->dev);
+	if (ret < 0)
+		return ret;
+
+	if (is_support_sw_smu(adev)) {
+		ret = smu_get_dpm_freq_range(&adev->smu, SMU_SCLK, &min_freq, &max_freq, true);
+		if (ret || val > max_freq || val < min_freq)
+			return -EINVAL;
+		ret = smu_set_soft_freq_range(&adev->smu, SMU_SCLK, (uint32_t)val, (uint32_t)val);
+	} else {
+		return 0;
+	}
+
+	pm_runtime_mark_last_busy(adev->ddev->dev);
+	pm_runtime_put_autosuspend(adev->ddev->dev);
+
+	if (ret)
+		return -EINVAL;
+
+	return 0;
+}
+
 DEFINE_SIMPLE_ATTRIBUTE(fops_ib_preempt, NULL,
 			amdgpu_debugfs_ib_preempt, "%llu\n");
 
+DEFINE_SIMPLE_ATTRIBUTE(fops_sclk_set, NULL,
+			amdgpu_debugfs_sclk_set, "%llu\n");
+
 int amdgpu_debugfs_init(struct amdgpu_device *adev)  {
 	int r, i;
@@ -1285,6 +1319,15 @@ int amdgpu_debugfs_init(struct amdgpu_device *adev)
 		return -EIO;
 	}
 
+	adev->smu.debugfs_sclk =
+		debugfs_create_file("amdgpu_force_sclk", 0200,
+				    adev->ddev->primary->debugfs_root, adev,
+				    &fops_sclk_set);
+	if (!(adev->smu.debugfs_sclk)) {
+		DRM_ERROR("unable to create amdgpu_set_sclk debugsfs file\n");
+		return -EIO;
+	}
+
 	/* Register debugfs entries for amdgpu_ttm */
 	r = amdgpu_ttm_debugfs_init(adev);
 	if (r) {
@@ -1353,6 +1396,7 @@ void amdgpu_debugfs_fini(struct amdgpu_device *adev)
 	}
 	amdgpu_ttm_debugfs_fini(adev);
 	debugfs_remove(adev->debugfs_preempt);
+	debugfs_remove(adev->smu.debugfs_sclk);
 }
 
 #else
diff --git a/drivers/gpu/drm/amd/powerplay/inc/amdgpu_smu.h b/drivers/gpu/drm/amd/powerplay/inc/amdgpu_smu.h
index 97b6714..36fe19c 100644
--- a/drivers/gpu/drm/amd/powerplay/inc/amdgpu_smu.h
+++ b/drivers/gpu/drm/amd/powerplay/inc/amdgpu_smu.h
@@ -371,6 +371,9 @@ struct smu_context
 	struct amd_pp_display_configuration  *display_config;
 	struct smu_baco_context		smu_baco;
 	void *od_settings;
+#if defined(CONFIG_DEBUG_FS)
+	struct dentry                   *debugfs_sclk;
+#endif
 
 	uint32_t pstate_sclk;
 	uint32_t pstate_mclk;
--
2.7.4