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Message-ID: <20251006092856.02fbfd9e@fedora>
Date: Mon, 6 Oct 2025 09:28:56 +0200
From: Boris Brezillon <boris.brezillon@...labora.com>
To: Loïc Molinari <loic.molinari@...labora.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, David Airlie
<airlied@...il.com>, Simona Vetter <simona@...ll.ch>, Jani Nikula
<jani.nikula@...ux.intel.com>, Joonas Lahtinen
<joonas.lahtinen@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
Tvrtko Ursulin <tursulin@...ulin.net>, Rob Herring <robh@...nel.org>,
Steven Price <steven.price@....com>, Liviu Dudau <liviu.dudau@....com>,
Melissa Wen <mwen@...lia.com>, Maíra Canal
<mcanal@...lia.com>, Hugh Dickins <hughd@...gle.com>, Baolin Wang
<baolin.wang@...ux.alibaba.com>, Andrew Morton <akpm@...ux-foundation.org>,
Al Viro <viro@...iv.linux.org.uk>, Mikołaj Wasiak
<mikolaj.wasiak@...el.com>, Christian Brauner <brauner@...nel.org>, Nitin
Gote <nitin.r.gote@...el.com>, Andi Shyti <andi.shyti@...ux.intel.com>,
Christopher Healy <healych@...zon.com>, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
linux-mm@...ck.org, kernel@...labora.com
Subject: Re: [PATCH v3 07/10] drm/panthor: Introduce huge tmpfs mount point
option
On Sat, 4 Oct 2025 11:30:50 +0200
Loïc Molinari <loic.molinari@...labora.com> wrote:
> Introduce the 'panthor.transparent_hugepage' boolean module parameter
> (false by default). When the parameter is set to true, a new tmpfs
> mount point is created and mounted using the 'huge=within_size'
> option. It's then used at GEM object creation instead of the default
> 'shm_mnt' mount point 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
>
> Signed-off-by: Loïc Molinari <loic.molinari@...labora.com>
> ---
> drivers/gpu/drm/panthor/panthor_device.c | 3 +++
> drivers/gpu/drm/panthor/panthor_drv.c | 7 +++++++
> drivers/gpu/drm/panthor/panthor_drv.h | 11 +++++++++++
> drivers/gpu/drm/panthor/panthor_gem.c | 19 +++++++++++++++++++
> drivers/gpu/drm/panthor/panthor_gem.h | 2 ++
> 5 files changed, 42 insertions(+)
> create mode 100644 drivers/gpu/drm/panthor/panthor_drv.h
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index 81df49880bd8..3c0387156bb9 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -17,6 +17,7 @@
> #include "panthor_devfreq.h"
> #include "panthor_device.h"
> #include "panthor_fw.h"
> +#include "panthor_gem.h"
> #include "panthor_gpu.h"
> #include "panthor_hw.h"
> #include "panthor_mmu.h"
> @@ -269,6 +270,8 @@ int panthor_device_init(struct panthor_device *ptdev)
> if (ret)
> goto err_unplug_fw;
>
> + panthor_gem_init(ptdev);
> +
> /* ~3 frames */
> pm_runtime_set_autosuspend_delay(ptdev->base.dev, 50);
> pm_runtime_use_autosuspend(ptdev->base.dev);
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> index fdbe89ef7f43..a2be3b904ca2 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> @@ -1556,6 +1556,7 @@ static const struct file_operations panthor_drm_driver_fops = {
> .read = drm_read,
> .llseek = noop_llseek,
> .mmap = panthor_mmap,
> + .get_unmapped_area = drm_gem_get_unmapped_area,
> .show_fdinfo = drm_show_fdinfo,
> .fop_flags = FOP_UNSIGNED_OFFSET,
> };
> @@ -1623,6 +1624,12 @@ static const struct drm_driver panthor_drm_driver = {
> #endif
> };
>
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +bool panthor_transparent_hugepage;
> +module_param_named(transparent_hugepage, panthor_transparent_hugepage, bool, 0400);
> +MODULE_PARM_DESC(transparent_hugepage, "Use a dedicated tmpfs mount point with Transparent Hugepage enabled (false = default)");
nit: I'd go for a slightly shorter name, like [panthor_]enable_thp.
The patch is
Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
regardless.
> +#endif
> +
> static int panthor_probe(struct platform_device *pdev)
> {
> struct panthor_device *ptdev;
> diff --git a/drivers/gpu/drm/panthor/panthor_drv.h b/drivers/gpu/drm/panthor/panthor_drv.h
> new file mode 100644
> index 000000000000..27fe9b6f77bd
> --- /dev/null
> +++ b/drivers/gpu/drm/panthor/panthor_drv.h
> @@ -0,0 +1,11 @@
> +// SPDX-License-Identifier: GPL-2.0 or MIT
> +/* Copyright 2025 Amazon.com, Inc. or its affiliates */
> +
> +#ifndef __PANTHOR_DRV_H__
> +#define __PANTHOR_DRV_H__
> +
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +extern bool panthor_transparent_hugepage;
> +#endif
> +
> +#endif
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> index 156c7a0b62a2..49b7d288bfdf 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -1,6 +1,7 @@
> // SPDX-License-Identifier: GPL-2.0 or MIT
> /* Copyright 2019 Linaro, Ltd, Rob Herring <robh@...nel.org> */
> /* Copyright 2023 Collabora ltd. */
> +/* Copyright 2025 Amazon.com, Inc. or its affiliates */
>
> #include <linux/cleanup.h>
> #include <linux/dma-buf.h>
> @@ -11,10 +12,28 @@
> #include <drm/panthor_drm.h>
>
> #include "panthor_device.h"
> +#include "panthor_drv.h"
> #include "panthor_fw.h"
> #include "panthor_gem.h"
> #include "panthor_mmu.h"
>
> +void panthor_gem_init(struct panthor_device *ptdev)
> +{
> + int err;
> +
> + if (!panthor_transparent_hugepage)
> + return;
> +
> + err = drm_gem_huge_mnt_create(&ptdev->base, "within_size");
> + if (err && err != -EEXIST) {
> + drm_warn(&ptdev->base, "Can't use Transparent Hugepage (%d)\n",
> + -err);
> + return;
> + }
> +
> + drm_info(&ptdev->base, "Using Transparent Hugepage\n");
> +}
> +
> #ifdef CONFIG_DEBUG_FS
> static void panthor_gem_debugfs_bo_init(struct panthor_gem_object *bo)
> {
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.h b/drivers/gpu/drm/panthor/panthor_gem.h
> index 80c6e24112d0..2eefe9104e5e 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.h
> +++ b/drivers/gpu/drm/panthor/panthor_gem.h
> @@ -136,6 +136,8 @@ struct panthor_gem_object *to_panthor_bo(struct drm_gem_object *obj)
> return container_of(to_drm_gem_shmem_obj(obj), struct panthor_gem_object, base);
> }
>
> +void panthor_gem_init(struct panthor_device *ptdev);
> +
> struct drm_gem_object *panthor_gem_create_object(struct drm_device *ddev, size_t size);
>
> int
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