[RFC] drm/amd: Drop gttsize module parameter

[Alex Deucher]

On Thu, Jan 16, 2025 at 1:29 PM Mario Limonciello <superm1 at kernel.org> wrote:
>
> From: Mario Limonciello <mario.limonciello at amd.com>
>
> When not set `gttsize` module parameter by default will get the
> value to use for the GTT pool from the TTM page limit, which is
> set by a separate module parameter.
>
> This inevitably leads to people not sure which one to set when they
> want more addressable memory for the GPU, and you'll end up seeing
> instructions online saying to set both.
>
> Drop the amdgpu module parameter and related code for it.  This way
> if users want to change the amount of addressable memory they can
> change it solely in TTM.
>

I suspect we probably want to keep it for compatibility with users
that still use this option to change their GTT size.

Alex


> Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu.h        | 1 -
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 7 -------
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 9 ---------
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c    | 9 ++-------
>  4 files changed, 2 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 5e55a44f9eef..e728974114bb 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -164,7 +164,6 @@ extern int amdgpu_modeset;
>  extern unsigned int amdgpu_vram_limit;
>  extern int amdgpu_vis_vram_limit;
>  extern int amdgpu_gart_size;
> -extern int amdgpu_gtt_size;
>  extern int amdgpu_moverate;
>  extern int amdgpu_audio;
>  extern int amdgpu_disp_priority;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 3774d12ebc4a..1b62b843e5fb 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -2031,13 +2031,6 @@ static int amdgpu_device_check_arguments(struct amdgpu_device *adev)
>                 amdgpu_gart_size = -1;
>         }
>
> -       if (amdgpu_gtt_size != -1 && amdgpu_gtt_size < 32) {
> -               /* gtt size must be greater or equal to 32M */
> -               dev_warn(adev->dev, "gtt size (%d) too small\n",
> -                                amdgpu_gtt_size);
> -               amdgpu_gtt_size = -1;
> -       }
> -
>         /* valid range is between 4 and 9 inclusive */
>         if (amdgpu_vm_fragment_size != -1 &&
>             (amdgpu_vm_fragment_size > 9 || amdgpu_vm_fragment_size < 4)) {
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index b911653dd8b6..62b09c518665 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -141,7 +141,6 @@ enum AMDGPU_DEBUG_MASK {
>  unsigned int amdgpu_vram_limit = UINT_MAX;
>  int amdgpu_vis_vram_limit;
>  int amdgpu_gart_size = -1; /* auto */
> -int amdgpu_gtt_size = -1; /* auto */
>  int amdgpu_moverate = -1; /* auto */
>  int amdgpu_audio = -1;
>  int amdgpu_disp_priority;
> @@ -279,14 +278,6 @@ module_param_named(vis_vramlimit, amdgpu_vis_vram_limit, int, 0444);
>  MODULE_PARM_DESC(gartsize, "Size of kernel GART to setup in megabytes (32, 64, etc., -1=auto)");
>  module_param_named(gartsize, amdgpu_gart_size, uint, 0600);
>
> -/**
> - * DOC: gttsize (int)
> - * Restrict the size of GTT domain (for userspace use) in MiB for testing.
> - * The default is -1 (Use 1/2 RAM, minimum value is 3GB).
> - */
> -MODULE_PARM_DESC(gttsize, "Size of the GTT userspace domain in megabytes (-1 = auto)");
> -module_param_named(gttsize, amdgpu_gtt_size, int, 0600);
> -
>  /**
>   * DOC: moverate (int)
>   * Set maximum buffer migration rate in MB/s. The default is -1 (8 MB/s).
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index e6fc89440210..e3fee81d8646 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1957,13 +1957,8 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
>         DRM_INFO("amdgpu: %uM of VRAM memory ready\n",
>                  (unsigned int)(adev->gmc.real_vram_size / (1024 * 1024)));
>
> -       /* Compute GTT size, either based on TTM limit
> -        * or whatever the user passed on module init.
> -        */
> -       if (amdgpu_gtt_size == -1)
> -               gtt_size = ttm_tt_pages_limit() << PAGE_SHIFT;
> -       else
> -               gtt_size = (uint64_t)amdgpu_gtt_size << 20;
> +       /* Compute GTT size, based on TTM limit */
> +       gtt_size = ttm_tt_pages_limit() << PAGE_SHIFT;
>
>         /* Initialize GTT memory pool */
>         r = amdgpu_gtt_mgr_init(adev, gtt_size);
> --
> 2.48.0
>