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authorDave Airlie <airlied@redhat.com>2019-05-28 08:25:46 +1000
committerDave Airlie <airlied@redhat.com>2019-05-28 08:59:11 +1000
commit88cd7a2c1b29f61a2a3fab76216a43f3b779e0cd (patch)
treeb8a4311c8f7edfc92c1055b6a5a86b1a5552878e /drivers/gpu/drm/drm_vram_helper_common.c
parentcd6c84d8f0cdc911df435bb075ba22ce3c605b07 (diff)
parent909fa3321d348ef69366aad9e84e1dd9ee0bd060 (diff)
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Merge tag 'drm-misc-next-2019-05-24' of git://anongit.freedesktop.org/drm/drm-misc into drm-next
drm-misc-next for v5.3, try #2: UAPI Changes: - Add HDR source metadata property. - Make drm.h compile on GNU/kFreeBSD by including stdint.h - Clarify how the userspace reviewer has to review new kernel UAPI. - Clarify that for using new UAPI, merging to drm-next or drm-misc-next should be enough. Cross-subsystem Changes: - video/hdmi: Add unpack function for DRM infoframes. - Device tree bindings: * Updating a property for Mali Midgard GPUs * Updating a property for STM32 DSI panel * Adding support for FriendlyELEC HD702E 800x1280 panel * Adding support for Evervision VGG804821 800x480 5.0" WVGA TFT panel * Adding support for the EDT ET035012DM6 3.5" 320x240 QVGA 24-bit RGB TFT. * Adding support for Three Five displays TFC S9700RTWV43TR-01B 800x480 panel with resistive touch found on TI's AM335X-EVM. * Adding support for EDT ETM0430G0DH6 480x272 panel. - Add OSD101T2587-53TS driver with DT bindings. - Add Samsung S6E63M0 panel driver with DT bindings. - Add VXT VL050-8048NT-C01 800x480 panel with DT bindings. - Dma-buf: - Make mmap callback actually optional. - Documentation updates. - Fix debugfs refcount inbalance. - Remove unused sync_dump function. - Fix device tree bindings in drm-misc-next after a botched merge. Core Changes: - Add support for HDR infoframes and related EDID parsing. - Remove prime sg_table caching, now done inside dma-buf. - Add shiny new drm_gem_vram helpers for simple VRAM drivers; with some fixes to the new API on top. - Small fix to job cleanup without timeout handler. - Documentation fixes to drm_fourcc. - Replace lookups of drm_format with struct drm_format_info; remove functions that become obsolete by this conversion. - Remove double include in bridge/panel.c and some drivers. - Remove drmP.h include from drm/edid and drm/dp. - Fix null pointer deref in drm_fb_helper_hotplug_event(). - Remove most members from drm_fb_helper_crtc, only mode_set is kept. - Remove race of fb helpers with userspace; only restore mode when userspace is not master. - Move legacy setup from drm_file.c to drm_legacy_misc.c - Rework scheduler job destruction. - drm/bus was removed, remove from TODO. - Add __drm_atomic_helper_crtc_reset() to subclass crtc_state, and convert some drivers to use it (conversion is not complete yet). - Bump vblank timeout wait to 100 ms for atomic. - Docbook fix for drm_hdmi_infoframe_set_hdr_metadata. Driver Changes: - sun4i: Use DRM_GEM_CMA_VMAP_DRIVER_OPS instead of definining manually. - v3d: Small cleanups, adding support for compute shaders, reservation/synchronization fixes and job management refactoring, fixes MMU and debugfs. - lima: Fix null pointer in irq handler on startup, set default timeout for scheduled jobs. - stm/ltdc: Assorted fixes and adding FB modifier support. - amdgpu: Avoid hw reset if guilty job was already signaled. - virtio: Add seqno to fences, add trace events, use correct flags for fence allocation. - Convert AST, bochs, mgag200, vboxvideo, hisilicon to the new drm_gem_vram API. - sun6i_mipi_dsi: Support DSI GENERIC_SHORT_WRITE_2 transfers. - bochs: Small fix to use PTR_RET_OR_ZERO and driver unload. - gma500: header fixes - cirrus: Remove unused files. - mediatek: Fix compiler warning after merging the HDR series. - vc4: Rework binner bo handling. Signed-off-by: Dave Airlie <airlied@redhat.com> From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/052875a5-27ba-3832-60c2-193d950afdff@linux.intel.com
Diffstat (limited to 'drivers/gpu/drm/drm_vram_helper_common.c')
-rw-r--r--drivers/gpu/drm/drm_vram_helper_common.c96
1 files changed, 96 insertions, 0 deletions
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..e9c9f9a80ba3
--- /dev/null
+++ b/drivers/gpu/drm/drm_vram_helper_common.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/module.h>
+
+/**
+ * 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.
+ *
+ * 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");