Commit 245f44e7 authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

drm/vram: Support top-down placement flag 



Pinning lots of small buffer objects, such as cursors or sprites, to video
memory can lead to fragmentation, which is a problem for devices with only
a small amount of memory. As a result, framebuffer images might not get
pinned, even though there's enough space available overall.

The flag DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks buffer objects to be pinned at
the high end of video memory. This leaves contiguous space available at
the memory's low end.

Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20190923172753.26593-2-tzimmermann@suse.de


Reviewed-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent 2ebb6701

drivers/gpu/drm/drm_gem_vram_helper.c

+15 −3
Original line number Diff line number Diff line
@@ -58,6 +58,7 @@ static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo, 
{

	unsigned int i;

	unsigned int c = 0;

	u32 invariant_flags = pl_flag & TTM_PL_FLAG_TOPDOWN;



	gbo->placement.placement = gbo->placements;

	gbo->placement.busy_placement = gbo->placements;
@@ -65,15 +66,18 @@ static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo, 
	if (pl_flag & TTM_PL_FLAG_VRAM)

		gbo->placements[c++].flags = TTM_PL_FLAG_WC |

					     TTM_PL_FLAG_UNCACHED |

					     TTM_PL_FLAG_VRAM;

					     TTM_PL_FLAG_VRAM |

					     invariant_flags;



	if (pl_flag & TTM_PL_FLAG_SYSTEM)

		gbo->placements[c++].flags = TTM_PL_MASK_CACHING |

					     TTM_PL_FLAG_SYSTEM;

					     TTM_PL_FLAG_SYSTEM |

					     invariant_flags;



	if (!c)

		gbo->placements[c++].flags = TTM_PL_MASK_CACHING |

					     TTM_PL_FLAG_SYSTEM;

					     TTM_PL_FLAG_SYSTEM |

					     invariant_flags;



	gbo->placement.num_placement = c;

	gbo->placement.num_busy_placement = c;
@@ -238,6 +242,14 @@ out: 
 * the buffer is pinned at its current location (video RAM or system

 * memory).

 *

 * Small buffer objects, such as cursor images, can lead to memory

 * fragmentation if they are pinned in the middle of video RAM. This

 * is especially a problem on devices with only a small amount of

 * video RAM. Fragmentation can prevent the primary framebuffer from

 * fitting in, even though there's enough memory overall. The modifier

 * DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks the buffer object to be pinned

 * at the high end of the memory region to avoid fragmentation.

 *

 * Returns:

 * 0 on success, or

 * a negative error code otherwise.

include/drm/drm_gem_vram_helper.h

+1 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ struct vm_area_struct; 


#define DRM_GEM_VRAM_PL_FLAG_VRAM	TTM_PL_FLAG_VRAM

#define DRM_GEM_VRAM_PL_FLAG_SYSTEM	TTM_PL_FLAG_SYSTEM

#define DRM_GEM_VRAM_PL_FLAG_TOPDOWN	TTM_PL_FLAG_TOPDOWN



/*

 * Buffer-object helpers

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