| Message ID | 1483521177-21794-4-git-send-email-benjamin.gaignard@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jan 04, 2017 at 10:12:57AM +0100, Benjamin Gaignard wrote: > 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 > > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> > --- > Documentation/gpu/drm-mm.rst | 11 ++++++ > drivers/gpu/drm/Kconfig | 4 +- > drivers/gpu/drm/drm_gem_cma_helper.c | 71 ++++++++++++++++++++++++++++++++++++ > include/drm/drm_gem_cma_helper.h | 17 +++++++++ > 4 files changed, 101 insertions(+), 2 deletions(-) > > diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst > index bca8085..9d4aa11 100644 > --- a/Documentation/gpu/drm-mm.rst > +++ b/Documentation/gpu/drm-mm.rst > @@ -303,6 +303,17 @@ 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`. I've switched this to the recommened struct member reference format, which is &file_operations.get_unmapped_area and merged all 3 patches. Thanks, Daniel > + > +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 f799696..c5b6f33 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 > @@ -98,7 +98,7 @@ 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 > diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c > index 1d6c335..19908bb 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/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 > -- > 1.9.1 >
diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst index bca8085..9d4aa11 100644 --- a/Documentation/gpu/drm-mm.rst +++ b/Documentation/gpu/drm-mm.rst @@ -303,6 +303,17 @@ 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 f799696..c5b6f33 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 @@ -98,7 +98,7 @@ 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 diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index 1d6c335..19908bb 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/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
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 Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org> --- Documentation/gpu/drm-mm.rst | 11 ++++++ drivers/gpu/drm/Kconfig | 4 +- drivers/gpu/drm/drm_gem_cma_helper.c | 71 ++++++++++++++++++++++++++++++++++++ include/drm/drm_gem_cma_helper.h | 17 +++++++++ 4 files changed, 101 insertions(+), 2 deletions(-)