From 85438a8ddf031f416758ecf8c080ff92075acb01 Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Wed, 8 May 2019 10:26:11 +0200 Subject: drm: Add |struct drm_gem_vram_object| and helpers The type |struct drm_gem_vram_object| implements a GEM object for simple framebuffer devices with dedicated video memory. The BO is either located in VRAM or system memory. The implementation has been created from the respective code in ast, bochs and mgag200. These drivers copy their implementation from each other; except for the names of several data types. The helpers are currently build with TTM, but this is considered an implementation detail and may change in future updates. v5: * do WARN_ON_ONCE for pin-count mismatches * allocate only 2 entries in placements array v4: * cleanups from checkpatch.pl * removed several fixed-size types from interfaces * DRM_VRAM_HELPER now selects DRM_TTM * remove separate config option for GEM VRAM v2: * rename to |struct drm_gem_vram_object| * move drm_is_gem_ttm() to a later patch in the series * add drm_gem_vram_kmap_at() * return is_iomem from kmap functions * redefine TTM placement flags for public interface * documentation fixes Signed-off-by: Thomas Zimmermann Link: http://patchwork.freedesktop.org/patch/msgid/20190508082630.15116-2-tzimmermann@suse.de Signed-off-by: Gerd Hoffmann --- drivers/gpu/drm/drm_vram_helper_common.c | 6 ++++++ 1 file changed, 6 insertions(+) create mode 100644 drivers/gpu/drm/drm_vram_helper_common.c (limited to 'drivers/gpu/drm/drm_vram_helper_common.c') diff --git a/drivers/gpu/drm/drm_vram_helper_common.c b/drivers/gpu/drm/drm_vram_helper_common.c new file mode 100644 index 000000000000..7c25daca18d0 --- /dev/null +++ b/drivers/gpu/drm/drm_vram_helper_common.c @@ -0,0 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include + +MODULE_DESCRIPTION("DRM VRAM memory-management helpers"); +MODULE_LICENSE("GPL"); -- cgit v1.2.3 From 59f5989ad42b6edd089b47895986ef15259822dc Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Wed, 8 May 2019 10:26:18 +0200 Subject: drm: Integrate VRAM MM into struct drm_device There's now a pointer to struct drm_vram_mm stored in struct drm_device. DRM drivers that use VRAM MM should use this field to refer to their instance of the data structure. Appropriate helpers are now provided as well. Adding struct drm_vram_mm to struct drm_device further avoids wrappers and boilerplate code in drivers. This patch implements default functions for callbacks in struct drm_driver and struct file_operations that use the struct drm_vram_mm stored in struct drm_device. Drivers that need to provide their own implementations can still do so. The patch also adds documentation for the VRAM helper library in general. v5: * set .llseek to no_llseek() from DRM_VRAM_MM_FILE_OPERATIONS v4: * cleanups from checkpatch.pl * document VRAM helper library Signed-off-by: Thomas Zimmermann Link: http://patchwork.freedesktop.org/patch/msgid/20190508082630.15116-9-tzimmermann@suse.de Signed-off-by: Gerd Hoffmann --- drivers/gpu/drm/drm_vram_helper_common.c | 92 ++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) (limited to 'drivers/gpu/drm/drm_vram_helper_common.c') diff --git a/drivers/gpu/drm/drm_vram_helper_common.c b/drivers/gpu/drm/drm_vram_helper_common.c index 7c25daca18d0..3b47f7002115 100644 --- a/drivers/gpu/drm/drm_vram_helper_common.c +++ b/drivers/gpu/drm/drm_vram_helper_common.c @@ -2,5 +2,97 @@ #include +/** + * DOC: overview + * + * This library provides &struct drm_gem_vram_object (GEM VRAM), a GEM + * buffer object that is backed by video RAM. It can be used for + * framebuffer devices with dedicated memory. The video RAM can be + * managed with &struct drm_vram_mm (VRAM MM). Both data structures are + * supposed to be used together, but can also be used individually. + * + * With the GEM interface userspace applications create, manage and destroy + * graphics buffers, such as an on-screen framebuffer. GEM does not provide + * an implementation of these interfaces. It's up to the DRM driver to + * provide an implementation that suits the hardware. If the hardware device + * contains dedicated video memory, the DRM driver can use the VRAM helper + * library. Each active buffer object is stored in video RAM. Active + * buffer are used for drawing the current frame, typically something like + * the frame's scanout buffer or the cursor image. If there's no more space + * left in VRAM, inactive GEM objects can be moved to system memory. + * + * The easiest way to use the VRAM helper library is to call + * drm_vram_helper_alloc_mm(). The function allocates and initializes an + * instance of &struct drm_vram_mm in &struct drm_device.vram_mm . Use + * &DRM_GEM_VRAM_DRIVER to initialize &struct drm_driver and + * &DRM_VRAM_MM_FILE_OPERATIONS to initialize &struct file_operations; + * as illustrated below. + * + * .. code-block:: c + * + * struct file_operations fops ={ + * .owner = THIS_MODULE, + * DRM_VRAM_MM_FILE_OPERATION + * }; + * struct drm_driver drv = { + * .driver_feature = DRM_ ... , + * .fops = &fops, + * DRM_GEM_VRAM_DRIVER + * }; + * + * int init_drm_driver() + * { + * struct drm_device *dev; + * uint64_t vram_base; + * unsigned long vram_size; + * int ret; + * + * // setup device, vram base and size + * // ... + * + * ret = drm_vram_helper_alloc_mm(dev, vram_base, vram_size, + * &drm_gem_vram_mm_funcs); + * if (ret) + * return ret; + * return 0; + * } + * + * This creates an instance of &struct drm_vram_mm, exports DRM userspace + * interfaces for GEM buffer management and initializes file operations to + * allow for accessing created GEM buffers. With this setup, the DRM driver + * manages an area of video RAM with VRAM MM and provides GEM VRAM objects + * to userspace. + * + * To clean up the VRAM memory management, call drm_vram_helper_release_mm() + * in the driver's clean-up code. + * + * .. code-block:: c + * + * void fini_drm_driver() + * { + * struct drm_device *dev = ...; + * + * drm_vram_helper_release_mm(dev); + * } + * + * For drawing or scanout operations, buffer object have to be pinned in video + * RAM. Call drm_gem_vram_pin() with &DRM_GEM_VRAM_PL_FLAG_VRAM or + * &DRM_GEM_VRAM_PL_FLAG_SYSTEM to pin a buffer object in video RAM or system + * memory. Call drm_gem_vram_unpin() to release the pinned object afterwards. + * If you have to evict a buffer object from video RAM (e.g., for freeing up + * memory), unpin the buffer and call drm_gem_vram_push_to_system(). + * + * A buffer object that is pinned in video RAM has a fixed address within that + * memory region. Call drm_gem_vram_offset() to retrieve this value. Typically + * it's used to program the hardware's scanout engine for framebuffers, set + * the cursor overlay's image for a mouse cursor, or use it as input to the + * hardware's draing engine. + * + * To access a buffer object's memory from the DRM driver, call + * drm_gem_vram_kmap(). It (optionally) maps the buffer into kernel address + * space and returns the memory address. Use drm_gem_vram_kunmap() to + * release the mapping. + */ + MODULE_DESCRIPTION("DRM VRAM memory-management helpers"); MODULE_LICENSE("GPL"); -- cgit v1.2.3 From 81da87f63a1edebcf8cbb811d387e353d9f89c7a Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Tue, 21 May 2019 13:08:29 +0200 Subject: drm: Replace drm_gem_vram_push_to_system() with kunmap + unpin The push-to-system function forces a buffer out of video RAM. This decision should rather be made by the memory manager. By replacing the function with calls to the kunmap and unpin functions, the buffer's memory becomes available, but the buffer remains in VRAM until it's evicted by a pin operation. This patch replaces the remaining instances of drm_gem_vram_push_to_system() in ast and mgag200, and removes the function from DRM. Signed-off-by: Thomas Zimmermann Acked-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20190521110831.20200-2-tzimmermann@suse.de Signed-off-by: Gerd Hoffmann --- drivers/gpu/drm/drm_vram_helper_common.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers/gpu/drm/drm_vram_helper_common.c') diff --git a/drivers/gpu/drm/drm_vram_helper_common.c b/drivers/gpu/drm/drm_vram_helper_common.c index 3b47f7002115..e9c9f9a80ba3 100644 --- a/drivers/gpu/drm/drm_vram_helper_common.c +++ b/drivers/gpu/drm/drm_vram_helper_common.c @@ -79,8 +79,6 @@ * RAM. Call drm_gem_vram_pin() with &DRM_GEM_VRAM_PL_FLAG_VRAM or * &DRM_GEM_VRAM_PL_FLAG_SYSTEM to pin a buffer object in video RAM or system * memory. Call drm_gem_vram_unpin() to release the pinned object afterwards. - * If you have to evict a buffer object from video RAM (e.g., for freeing up - * memory), unpin the buffer and call drm_gem_vram_push_to_system(). * * A buffer object that is pinned in video RAM has a fixed address within that * memory region. Call drm_gem_vram_offset() to retrieve this value. Typically -- cgit v1.2.3