From c655a5e058f0da364108dda740ea69f53bfaaae4 Mon Sep 17 00:00:00 2001
From: shaochunk <shaochunk@nvidia.com>
Date: Tue, 2 May 2023 15:16:57 +0800
Subject: [PATCH] gpu: nvgpu: specify devfreq timer through dt

Originally,
nvgpu uses deferrable timer for devfreq polling by default,
this leads to issues below because of unstable polling interval.
 - out of time frequency scaling
 - unstable GPU frequency scaling

This change lets users be able to specify devfreq timer through dt.
If the dt node 'devfreq-timer' equals to 'delayed', then gpu will uses
delayed timer for devfreq polling.

Bug 3823798

Change-Id: Idc0849b4a6b8af52fda8e88f5c831f183b7a27de
Signed-off-by: shaochunk <shaochunk@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2897026
Reviewed-by: Divya Singhatwaria <dsinghatwari@nvidia.com>
Reviewed-by: Rajkumar Kasirajan <rkasirajan@nvidia.com>
GVS: Gerrit_Virtual_Submit <buildbot_gerritrpt@nvidia.com>
---
 drivers/gpu/nvgpu/os/linux/driver_common.c | 28 ++++++++++++++++++++++
 drivers/gpu/nvgpu/os/linux/driver_common.h |  3 ++-
 drivers/gpu/nvgpu/os/linux/scale.c         |  4 +++-
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/nvgpu/os/linux/driver_common.c b/drivers/gpu/nvgpu/os/linux/driver_common.c
index 561c7de26..60f2e9054 100644
--- a/drivers/gpu/nvgpu/os/linux/driver_common.c
+++ b/drivers/gpu/nvgpu/os/linux/driver_common.c
@@ -23,6 +23,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/of_platform.h>
 #include <uapi/linux/nvgpu.h>
+#include <linux/devfreq.h>
 
 #include <nvgpu/defaults.h>
 #include <nvgpu/kmem.h>
@@ -43,6 +44,7 @@
 #include "os_linux.h"
 #include "sysfs.h"
 #include "ioctl.h"
+#include "scale.h"
 
 #define EMC3D_DEFAULT_RATIO 750
 
@@ -73,6 +75,32 @@ void nvgpu_read_support_gpu_tools(struct gk20a *g)
 	}
 }
 
+void nvgpu_read_devfreq_timer(struct gk20a *g)
+{
+	struct device_node *np;
+	int ret = 0;
+	const char *timer;
+
+	np = nvgpu_get_node(g);
+	ret = of_property_read_string(np, "devfreq-timer", &timer);
+	if (ret != 0) {
+		nvgpu_log_info(g, "GPU devfreq monitor uses default timer");
+	} else {
+		if (strncmp(timer, "deferrable",
+					sizeof("deferrable") - 1) == 0) {
+			g->scale_profile->devfreq_profile.timer =
+						DEVFREQ_TIMER_DEFERRABLE;
+		} else if (strncmp(timer, "delayed",
+					sizeof("delayed") - 1) == 0) {
+			g->scale_profile->devfreq_profile.timer =
+						DEVFREQ_TIMER_DELAYED;
+		} else {
+			nvgpu_err(g, "dt specified "
+				"invalid devfreq timer for GPU: %s", timer);
+		}
+	}
+}
+
 static void nvgpu_init_vars(struct gk20a *g)
 {
 	struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
diff --git a/drivers/gpu/nvgpu/os/linux/driver_common.h b/drivers/gpu/nvgpu/os/linux/driver_common.h
index f1c46ac1f..caf1f1ad8 100644
--- a/drivers/gpu/nvgpu/os/linux/driver_common.h
+++ b/drivers/gpu/nvgpu/os/linux/driver_common.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2021, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2016-2023, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -24,5 +24,6 @@ int nvgpu_probe(struct gk20a *g,
 
 void nvgpu_init_gk20a(struct gk20a *g);
 void nvgpu_read_support_gpu_tools(struct gk20a *g);
+void nvgpu_read_devfreq_timer(struct gk20a *g);
 
 #endif
diff --git a/drivers/gpu/nvgpu/os/linux/scale.c b/drivers/gpu/nvgpu/os/linux/scale.c
index 9942f242f..f8e0d7385 100644
--- a/drivers/gpu/nvgpu/os/linux/scale.c
+++ b/drivers/gpu/nvgpu/os/linux/scale.c
@@ -1,7 +1,7 @@
 /*
  * gk20a clock scaling profile
  *
- * Copyright (c) 2013-2022, NVIDIA Corporation. All rights reserved.
+ * Copyright (c) 2013-2023, NVIDIA Corporation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -40,6 +40,7 @@
 #include "platform_gk20a.h"
 #include "scale.h"
 #include "os_linux.h"
+#include "driver_common.h"
 
 /*
  * gk20a_scale_qos_notify()
@@ -520,6 +521,7 @@ void gk20a_scale_init(struct device *dev)
 		int error = 0;
 
 		register_gpu_opp(dev);
+		nvgpu_read_devfreq_timer(g);
 
 		profile->devfreq_profile.initial_freq =
 			profile->devfreq_profile.freq_table[0];