gpu: nvgpu: add disable_syncpoints debugfs node

To test semaphore-related bugs with igpus, add a debugfs node called
"disable_syncpoints" to override the "has_syncpoints" platform flag.
This makes job synchronization use semaphores, for example.

NVGPU_GPU_FLAGS_HAS_SYNCPOINTS is still reported in gpu characteristics
if the platform supports that, because it is filled in during boot.

Jira NVGPU-18

Change-Id: I58c815f896a6054df472f571012c239f1478bf07
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/1293972
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

2 files changed, 13 insertions, 3 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/debug_gk20a.c b/drivers/gpu/nvgpu/gk20a/debug_gk20a.c
index 609ddf72..37ba720a 100644
--- a/drivers/gpu/nvgpu/gk20a/debug_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/debug_gk20a.c
@@ -1,7 +1,7 @@
 /*
  * drivers/video/tegra/host/t20/debug_gk20a.c
  *
- * Copyright (C) 2011-2016 NVIDIA Corporation.  All rights reserved.
+ * Copyright (C) 2011-2017 NVIDIA Corporation.  All rights reserved.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -412,6 +412,9 @@ void gk20a_debug_init(struct device *dev, const char *debugfs_symlink)
         debugfs_create_u32("ch_wdt_timeout_ms", S_IRUGO|S_IWUSR,
                 platform->debugfs, &platform->ch_wdt_timeout_ms);
 
+        debugfs_create_bool("disable_syncpoints", S_IRUGO|S_IWUSR,
+                platform->debugfs, &platform->disable_syncpoints);
+
 #if defined(GK20A_DEBUG)
         debugfs_create_u32("dbg_mask", S_IRUGO|S_IWUSR,
                 platform->debugfs, &gk20a_dbg_mask);
diff --git a/drivers/gpu/nvgpu/gk20a/platform_gk20a.h b/drivers/gpu/nvgpu/gk20a/platform_gk20a.h
index 6966394f..e71dbf32 100644
--- a/drivers/gpu/nvgpu/gk20a/platform_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/platform_gk20a.h
@@ -1,7 +1,7 @@
 /*
  * GK20A Platform (SoC) Interface
  *
- * Copyright (c) 2014-2016, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2014-2017, 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,
@@ -18,6 +18,7 @@
 
 #include <linux/device.h>
 #include <linux/dma-attrs.h>
+#include <linux/version.h>
 
 #define GK20A_CLKS_MAX          4
 
@@ -54,6 +55,12 @@ struct gk20a_platform {
 
         /* Should be populated at probe. */
         bool has_syncpoints;
+        /* Debugfs knob for forcing syncpt support off in runtime. */
+#if LINUX_VERSION_CODE < KERNEL_VERSION(4,4,0)
+        u32 disable_syncpoints;
+#else
+        bool disable_syncpoints;
+#endif
 
         /* channel limit after which to start aggressive sync destroy */
         unsigned int aggressive_sync_destroy_thresh;
@@ -265,7 +272,7 @@ extern struct gk20a_platform vgpu_tegra_platform;
 static inline bool gk20a_platform_has_syncpoints(struct device *dev)
 {
         struct gk20a_platform *p = dev_get_drvdata(dev);
-        return p->has_syncpoints;
+        return p->has_syncpoints && !p->disable_syncpoints;
 }
 
 int gk20a_tegra_busy(struct device *dev);