[PATCH 08/11] drm/amdgpu: stop using TTM_MEMTYPE_FLAG_MAPPABLE

[Chauhan, Madhav]

[AMD Public Use]

-----Original Message-----
From: daniel at ffwll.ch <daniel at ffwll.ch> 
Sent: Tuesday, July 21, 2020 2:58 PM
Cc: dri-devel at lists.freedesktop.org; Chauhan, Madhav <Madhav.Chauhan at amd.com>; michael.j.ruhl at intel.com; tzimmermann at suse.de
Subject: Re: [PATCH 08/11] drm/amdgpu: stop using TTM_MEMTYPE_FLAG_MAPPABLE

On Tue, Jul 21, 2020 at 09:32:42AM +0200, Christian König wrote:
> The driver does support some not-mapable resources, but those are 
> already handled correctly in the switch/case statement in the code.
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 44fa8bc49d18..0dd5e802091d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -84,7 +84,7 @@ static int amdgpu_init_mem_type(struct ttm_bo_device *bdev, uint32_t type,
>  	switch (type) {
>  	case TTM_PL_SYSTEM:
>  		/* System memory */
> -		man->flags = TTM_MEMTYPE_FLAG_MAPPABLE;
> +		man->flags = 0;
>  		man->available_caching = TTM_PL_MASK_CACHING;
>  		man->default_caching = TTM_PL_FLAG_CACHED;
>  		break;
> @@ -93,13 +93,12 @@ static int amdgpu_init_mem_type(struct ttm_bo_device *bdev, uint32_t type,
>  		man->func = &amdgpu_gtt_mgr_func;
>  		man->available_caching = TTM_PL_MASK_CACHING;
>  		man->default_caching = TTM_PL_FLAG_CACHED;
> -		man->flags = TTM_MEMTYPE_FLAG_MAPPABLE;
> +		man->flags = 0;
>  		break;
>  	case TTM_PL_VRAM:
>  		/* "On-card" video ram */
>  		man->func = &amdgpu_vram_mgr_func;
> -		man->flags = TTM_MEMTYPE_FLAG_FIXED |
> -			     TTM_MEMTYPE_FLAG_MAPPABLE;
> +		man->flags = TTM_MEMTYPE_FLAG_FIXED;
>  		man->available_caching = TTM_PL_FLAG_UNCACHED | TTM_PL_FLAG_WC;
>  		man->default_caching = TTM_PL_FLAG_WC;
>  		break;
> @@ -796,7 +795,6 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
>   */
>  static int amdgpu_ttm_io_mem_reserve(struct ttm_bo_device *bdev, 
> struct ttm_mem_reg *mem)  {
> -	struct ttm_mem_type_manager *man = &bdev->man[mem->mem_type];
>  	struct amdgpu_device *adev = amdgpu_ttm_adev(bdev);
>  	struct drm_mm_node *mm_node = mem->mm_node;
>  
> @@ -805,8 +803,7 @@ static int amdgpu_ttm_io_mem_reserve(struct ttm_bo_device *bdev, struct ttm_mem_
>  	mem->bus.size = mem->num_pages << PAGE_SHIFT;
>  	mem->bus.base = 0;
>  	mem->bus.is_iomem = false;
> -	if (!(man->flags & TTM_MEMTYPE_FLAG_MAPPABLE))
> -		return -EINVAL;

This check catches the various special on-board memories, or at least I couldnt' find where mmap for these is disallowed.

For various on board memories (GDS, GWS, OA). TTM_MEMTYPE_FLAG_MAPPABLE  is not added while initializing the BO manger.
Can you please elaborate??

Regards,
Madhav

-Daniel

> +
>  	switch (mem->mem_type) {
>  	case TTM_PL_SYSTEM:
>  		/* system memory */
> --
> 2.17.1
> 
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--
Daniel Vetter
Software Engineer, Intel Corporation
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