Some SoC without MMU have display driver where a drm/kms driver could be implemented.
Before doing such kind of thing drm/kms must allow to use mmuless devices. This patch propose to remove MMU configuration flag and add a cma helper function to help implementing mmuless display driver
version 4: - add documentation about drm_gem_cma_get_unmapped_area() - stub it MMU case
version 5: - Make all driver that select DRM_TTM depends on MMU (issue reported by kbuild test robot)
Signed-off-by: Benjamin Gaignard benjamin.gaignard@linaro.org [danvet: Use recommended struct member references in kernel-doc.] Signed-off-by: Daniel Vetter daniel.vetter@ffwll.ch Link: http://patchwork.freedesktop.org/patch/msgid/1483521177-21794-4-git-send-ema... --- Documentation/gpu/drm-mm.rst | 11 +++++ drivers/gpu/drm/Kconfig | 8 ++-- drivers/gpu/drm/ast/Kconfig | 2 +- drivers/gpu/drm/bochs/Kconfig | 2 +- drivers/gpu/drm/cirrus/Kconfig | 2 +- drivers/gpu/drm/drm_gem_cma_helper.c | 71 +++++++++++++++++++++++++++++++++ drivers/gpu/drm/gma500/Kconfig | 2 +- drivers/gpu/drm/hisilicon/hibmc/Kconfig | 2 +- drivers/gpu/drm/mgag200/Kconfig | 2 +- drivers/gpu/drm/nouveau/Kconfig | 2 +- drivers/gpu/drm/qxl/Kconfig | 2 +- drivers/gpu/drm/virtio/Kconfig | 2 +- drivers/gpu/drm/vmwgfx/Kconfig | 2 +- include/drm/drm_gem_cma_helper.h | 17 ++++++++ 14 files changed, 113 insertions(+), 14 deletions(-)
diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst index d3c6d77..1ea94fc 100644 --- a/Documentation/gpu/drm-mm.rst +++ b/Documentation/gpu/drm-mm.rst @@ -310,6 +310,17 @@ created. Drivers that want to map the GEM object upfront instead of handling page faults can implement their own mmap file operation handler.
+For platforms without MMU the GEM core provides a helper method +:c:func:`drm_gem_cma_get_unmapped_area`. The mmap() routines will call +this to get a proposed address for the mapping. + +To use :c:func:`drm_gem_cma_get_unmapped_area`, drivers must fill the +struct :c:type:`struct file_operations <file_operations>` get_unmapped_area +field with a pointer on :c:func:`drm_gem_cma_get_unmapped_area`. + +More detailed information about get_unmapped_area can be found in +Documentation/nommu-mmap.txt + Memory Coherency ----------------
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index d56b85c..6f3f9e6 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -6,7 +6,7 @@ # menuconfig DRM tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)" - depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU && HAS_DMA + depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA select HDMI select FB_CMDLINE select I2C @@ -113,7 +113,7 @@ config DRM_LOAD_EDID_FIRMWARE
config DRM_TTM tristate - depends on DRM + depends on DRM && MMU help GPU memory management subsystem for devices with multiple GPU memory types. Will be enabled automatically if a device driver @@ -146,7 +146,7 @@ source "drivers/gpu/drm/arm/Kconfig"
config DRM_RADEON tristate "ATI Radeon" - depends on DRM && PCI + depends on DRM && PCI && MMU select FW_LOADER select DRM_KMS_HELPER select DRM_TTM @@ -166,7 +166,7 @@ source "drivers/gpu/drm/radeon/Kconfig"
config DRM_AMDGPU tristate "AMD GPU" - depends on DRM && PCI + depends on DRM && PCI && MMU select FW_LOADER select DRM_KMS_HELPER select DRM_TTM diff --git a/drivers/gpu/drm/ast/Kconfig b/drivers/gpu/drm/ast/Kconfig index 15f6ce7..9647e1f 100644 --- a/drivers/gpu/drm/ast/Kconfig +++ b/drivers/gpu/drm/ast/Kconfig @@ -1,6 +1,6 @@ config DRM_AST tristate "AST server chips" - depends on DRM && PCI + depends on DRM && PCI && MMU select DRM_TTM select DRM_KMS_HELPER select DRM_TTM diff --git a/drivers/gpu/drm/bochs/Kconfig b/drivers/gpu/drm/bochs/Kconfig index f739763..bd27180 100644 --- a/drivers/gpu/drm/bochs/Kconfig +++ b/drivers/gpu/drm/bochs/Kconfig @@ -1,6 +1,6 @@ config DRM_BOCHS tristate "DRM Support for bochs dispi vga interface (qemu stdvga)" - depends on DRM && PCI + depends on DRM && PCI && MMU select DRM_KMS_HELPER select DRM_TTM help diff --git a/drivers/gpu/drm/cirrus/Kconfig b/drivers/gpu/drm/cirrus/Kconfig index 04b3c16..ca38098 100644 --- a/drivers/gpu/drm/cirrus/Kconfig +++ b/drivers/gpu/drm/cirrus/Kconfig @@ -1,6 +1,6 @@ config DRM_CIRRUS_QEMU tristate "Cirrus driver for QEMU emulated device" - depends on DRM && PCI + depends on DRM && PCI && MMU select DRM_KMS_HELPER select DRM_TTM help diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index e0806a2a..5cf38a4 100644 --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -358,6 +358,77 @@ int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma) } EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
+#ifndef CONFIG_MMU +/** + * drm_gem_cma_get_unmapped_area - propose address for mapping in noMMU cases + * @filp: file object + * @addr: memory address + * @len: buffer size + * @pgoff: page offset + * @flags: memory flags + * + * This function is used in noMMU platforms to propose address mapping + * for a given buffer. + * It's intended to be used as a direct handler for the struct + * &file_operations.get_unmapped_area operation. + * + * Returns: + * mapping address on success or a negative error code on failure. + */ +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp, + unsigned long addr, + unsigned long len, + unsigned long pgoff, + unsigned long flags) +{ + struct drm_gem_cma_object *cma_obj; + struct drm_gem_object *obj = NULL; + struct drm_file *priv = filp->private_data; + struct drm_device *dev = priv->minor->dev; + struct drm_vma_offset_node *node; + + if (drm_device_is_unplugged(dev)) + return -ENODEV; + + drm_vma_offset_lock_lookup(dev->vma_offset_manager); + node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager, + pgoff, + len >> PAGE_SHIFT); + if (likely(node)) { + obj = container_of(node, struct drm_gem_object, vma_node); + /* + * When the object is being freed, after it hits 0-refcnt it + * proceeds to tear down the object. In the process it will + * attempt to remove the VMA offset and so acquire this + * mgr->vm_lock. Therefore if we find an object with a 0-refcnt + * that matches our range, we know it is in the process of being + * destroyed and will be freed as soon as we release the lock - + * so we have to check for the 0-refcnted object and treat it as + * invalid. + */ + if (!kref_get_unless_zero(&obj->refcount)) + obj = NULL; + } + + drm_vma_offset_unlock_lookup(dev->vma_offset_manager); + + if (!obj) + return -EINVAL; + + if (!drm_vma_node_is_allowed(node, priv)) { + drm_gem_object_unreference_unlocked(obj); + return -EACCES; + } + + cma_obj = to_drm_gem_cma_obj(obj); + + drm_gem_object_unreference_unlocked(obj); + + return cma_obj->vaddr ? (unsigned long)cma_obj->vaddr : -EINVAL; +} +EXPORT_SYMBOL_GPL(drm_gem_cma_get_unmapped_area); +#endif + #ifdef CONFIG_DEBUG_FS /** * drm_gem_cma_describe - describe a CMA GEM object for debugfs diff --git a/drivers/gpu/drm/gma500/Kconfig b/drivers/gpu/drm/gma500/Kconfig index 8906d67..df11582 100644 --- a/drivers/gpu/drm/gma500/Kconfig +++ b/drivers/gpu/drm/gma500/Kconfig @@ -1,6 +1,6 @@ config DRM_GMA500 tristate "Intel GMA5/600 KMS Framebuffer" - depends on DRM && PCI && X86 + depends on DRM && PCI && X86 && MMU select DRM_KMS_HELPER select DRM_TTM # GMA500 depends on ACPI_VIDEO when ACPI is enabled, just like i915 diff --git a/drivers/gpu/drm/hisilicon/hibmc/Kconfig b/drivers/gpu/drm/hisilicon/hibmc/Kconfig index 380622a..c7129dc 100644 --- a/drivers/gpu/drm/hisilicon/hibmc/Kconfig +++ b/drivers/gpu/drm/hisilicon/hibmc/Kconfig @@ -1,6 +1,6 @@ config DRM_HISI_HIBMC tristate "DRM Support for Hisilicon Hibmc" - depends on DRM && PCI + depends on DRM && PCI && MMU select DRM_KMS_HELPER select DRM_TTM
diff --git a/drivers/gpu/drm/mgag200/Kconfig b/drivers/gpu/drm/mgag200/Kconfig index 520e5e6..db58578 100644 --- a/drivers/gpu/drm/mgag200/Kconfig +++ b/drivers/gpu/drm/mgag200/Kconfig @@ -1,6 +1,6 @@ config DRM_MGAG200 tristate "Kernel modesetting driver for MGA G200 server engines" - depends on DRM && PCI + depends on DRM && PCI && MMU select DRM_KMS_HELPER select DRM_TTM help diff --git a/drivers/gpu/drm/nouveau/Kconfig b/drivers/gpu/drm/nouveau/Kconfig index 0f2f0af..c02a134 100644 --- a/drivers/gpu/drm/nouveau/Kconfig +++ b/drivers/gpu/drm/nouveau/Kconfig @@ -1,6 +1,6 @@ config DRM_NOUVEAU tristate "Nouveau (NVIDIA) cards" - depends on DRM && PCI + depends on DRM && PCI && MMU select FW_LOADER select DRM_KMS_HELPER select DRM_TTM diff --git a/drivers/gpu/drm/qxl/Kconfig b/drivers/gpu/drm/qxl/Kconfig index da45b11..378da59 100644 --- a/drivers/gpu/drm/qxl/Kconfig +++ b/drivers/gpu/drm/qxl/Kconfig @@ -1,6 +1,6 @@ config DRM_QXL tristate "QXL virtual GPU" - depends on DRM && PCI + depends on DRM && PCI && MMU select DRM_KMS_HELPER select DRM_TTM select CRC32 diff --git a/drivers/gpu/drm/virtio/Kconfig b/drivers/gpu/drm/virtio/Kconfig index 81d1807..0c384d9 100644 --- a/drivers/gpu/drm/virtio/Kconfig +++ b/drivers/gpu/drm/virtio/Kconfig @@ -1,6 +1,6 @@ config DRM_VIRTIO_GPU tristate "Virtio GPU driver" - depends on DRM && VIRTIO + depends on DRM && VIRTIO && MMU select DRM_KMS_HELPER select DRM_TTM help diff --git a/drivers/gpu/drm/vmwgfx/Kconfig b/drivers/gpu/drm/vmwgfx/Kconfig index fb7b82a..8c308da 100644 --- a/drivers/gpu/drm/vmwgfx/Kconfig +++ b/drivers/gpu/drm/vmwgfx/Kconfig @@ -1,6 +1,6 @@ config DRM_VMWGFX tristate "DRM driver for VMware Virtual GPU" - depends on DRM && PCI && X86 + depends on DRM && PCI && X86 && MMU select FB_DEFERRED_IO select FB_CFB_FILLRECT select FB_CFB_COPYAREA diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h index acd6af8..2abcd51 100644 --- a/include/drm/drm_gem_cma_helper.h +++ b/include/drm/drm_gem_cma_helper.h @@ -53,6 +53,23 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
extern const struct vm_operations_struct drm_gem_cma_vm_ops;
+#ifndef CONFIG_MMU +unsigned long drm_gem_cma_get_unmapped_area(struct file *filp, + unsigned long addr, + unsigned long len, + unsigned long pgoff, + unsigned long flags); +#else +static inline unsigned long drm_gem_cma_get_unmapped_area(struct file *filp, + unsigned long addr, + unsigned long len, + unsigned long pgoff, + unsigned long flags) +{ + return -EINVAL; +} +#endif + #ifdef CONFIG_DEBUG_FS void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m); #endif