[PATCH v13 09/10] drm/panfrost: Introduce huge tmpfs mountpoint option

Loïc Molinari
2025-12-05T18:23:00Z

Introduce the 'panfrost.transparent_hugepage' boolean module parameter
(false by default). When the parameter is set to true, a new tmpfs
mountpoint is created and mounted using the 'huge=within_size'
option. It's then used at GEM object creation instead of the default
'shm_mnt' mountpoint in order to enable Transparent Hugepage (THP) for
the object (without having to rely on a system wide parameter).

v3:
- use huge tmpfs mountpoint in drm_device

v4:
- fix builds with CONFIG_TRANSPARENT_HUGEPAGE=n
- clean up mountpoint creation error handling
- print negative error value

v5:
- use drm_gem_has_huge_tmp() helper
- get rid of CONFIG_TRANSPARENT_HUGEPAGE ifdefs

v9:
- replace drm_gem_has_huge_tmp() by drm_gem_get_huge_tmp()

v11:
- enable 'panfrost.transparent_hugepage' by default

Signed-off-by: Loïc Molinari <loic.molinari@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
---
drivers/gpu/drm/panfrost/panfrost_device.c | 3 +++
drivers/gpu/drm/panfrost/panfrost_drv.c | 6 ++++++
drivers/gpu/drm/panfrost/panfrost_drv.h | 9 +++++++++
drivers/gpu/drm/panfrost/panfrost_gem.c | 18 ++++++++++++++++++
drivers/gpu/drm/panfrost/panfrost_gem.h | 2 ++
5 files changed, 38 insertions(+)
create mode 100644 drivers/gpu/drm/panfrost/panfrost_drv.h

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
index c61b97af120c..dedc13e56631 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.c
+++ b/drivers/gpu/drm/panfrost/panfrost_device.c
@@ -12,6 +12,7 @@
#include "panfrost_device.h"
#include "panfrost_devfreq.h"
#include "panfrost_features.h"
+#include "panfrost_gem.h"
#include "panfrost_issues.h"
#include "panfrost_gpu.h"
#include "panfrost_job.h"
@@ -267,6 +268,8 @@ int panfrost_device_init(struct panfrost_device *pfdev)
if (err)
goto out_job;

+ panfrost_gem_init(pfdev);
+
return 0;
out_job:
panfrost_jm_fini(pfdev);
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
index 7d8c7c337606..4f5f19eda587 100644
--- a/drivers/gpu/drm/panfrost/panfrost_drv.c
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
@@ -858,6 +858,12 @@ static const struct drm_driver panfrost_drm_driver = {
#endif
};

+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+bool panfrost_transparent_hugepage = true;
+module_param_named(transparent_hugepage, panfrost_transparent_hugepage, bool, 0400);
+MODULE_PARM_DESC(transparent_hugepage, "Use a dedicated tmpfs mount point with Transparent Hugepage enabled (true = default)");
+#endif
+
static int panfrost_probe(struct platform_device *pdev)
{
struct panfrost_device *pfdev;
diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.h b/drivers/gpu/drm/panfrost/panfrost_drv.h
new file mode 100644
index 000000000000..edeb093eb6da
--- /dev/null
+++ b/drivers/gpu/drm/panfrost/panfrost_drv.h
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+/* Copyright 2025 Amazon.com, Inc. or its affiliates */
+
+#ifndef __PANFROST_DRV_H__
+#define __PANFROST_DRV_H__
+
+extern bool panfrost_transparent_hugepage;
+
+#endif
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 8041b65c6609..c1688a542ec2 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright 2019 Linaro, Ltd, Rob Herring <robh@kernel.org> */
+/* Copyright 2025 Amazon.com, Inc. or its affiliates */

#include <linux/cleanup.h>
#include <linux/err.h>
@@ -10,9 +11,26 @@
#include <drm/panfrost_drm.h>
#include <drm/drm_print.h>
#include "panfrost_device.h"
+#include "panfrost_drv.h"
#include "panfrost_gem.h"
#include "panfrost_mmu.h"

+void panfrost_gem_init(struct panfrost_device *pfdev)
+{
+ int err;
+
+ if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
+ !panfrost_transparent_hugepage)
+ return;
+
+ err = drm_gem_huge_mnt_create(&pfdev->base, "within_size");
+ if (drm_gem_get_huge_mnt(&pfdev->base))
+ drm_info(&pfdev->base, "Using Transparent Hugepage\n");
+ else if (err)
+ drm_warn(&pfdev->base, "Can't use Transparent Hugepage (%d)\n",
+ err);
+}
+
#ifdef CONFIG_DEBUG_FS
static void panfrost_gem_debugfs_bo_add(struct panfrost_device *pfdev,
struct panfrost_gem_object *bo)
diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
index 8de3e76f2717..1a62529ff06f 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.h
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
@@ -124,6 +124,8 @@ drm_mm_node_to_panfrost_mapping(struct drm_mm_node *node)
return container_of(node, struct panfrost_gem_mapping, mmnode);
}

+void panfrost_gem_init(struct panfrost_device *pfdev);
+
struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, size_t size);

struct drm_gem_object *
--
2.47.3