gpu: nvgpu: add support for disabling l3 via DT

On volta the GPU determines whether to do L3 allocation for a mapping by
checking bit 36 of the physical address. So if a mapping should allocate lines
in the L3 this bit must be set.

However, when the physical addresses for 64GB of RAM uses the 36th bit
resulting in a conflict. Thus, add support for disabling l3 support
for SKUs having 64GB of physical memory.

Bug 3486025

Signed-off-by: Debarshi Dutta <ddutta@nvidia.com>
Change-Id: Ic540e754274cf1d9e6625493962699d21509e540
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2661548
Reviewed-by: Brad Griffis <bgriffis@nvidia.com>
Reviewed-by: Bibek Basu <bbasu@nvidia.com>
Tested-by: Brad Griffis <bgriffis@nvidia.com>
GVS: Gerrit_Virtual_Submit

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/gpu/nvgpu/os/linux/driver_common.c b/drivers/gpu/nvgpu/os/linux/driver_common.c
index 602d325d..8f5872dc 100644
--- a/drivers/gpu/nvgpu/os/linux/driver_common.c
+++ b/drivers/gpu/nvgpu/os/linux/driver_common.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2021, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2016-2022, 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/dma-mapping.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
+#include <linux/of_platform.h>
 #include <uapi/linux/nvgpu.h>
 
 #include <nvgpu/defaults.h>
@@ -241,6 +242,8 @@ int nvgpu_probe(struct gk20a *g,
         struct device *dev = dev_from_gk20a(g);
         struct gk20a_platform *platform = dev_get_drvdata(dev);
         int err = 0;
+        struct device_node *np = dev->of_node;
+        bool disable_l3_alloc = false;
 
         nvgpu_init_vars(g);
         nvgpu_init_gr_vars(g);
@@ -265,6 +268,12 @@ int nvgpu_probe(struct gk20a *g,
                 return err;
         }
 
+        disable_l3_alloc = of_property_read_bool(np, "disable_l3_alloc");
+        if (disable_l3_alloc) {
+                nvgpu_log_info(g, "L3 alloc is disabled\n");
+                __nvgpu_set_enabled(g, NVGPU_DISABLE_L3_SUPPORT, true);
+        }
+
         nvgpu_init_mm_vars(g);
 
         /* platform probe can defer do user init only if probe succeeds */