On Wed, Dec 07, 2016 at 04:32:44PM +0200, Laurent Pinchart wrote: > Hi Benjamin, > > Thank you for the patch. > > On Wednesday 07 Dec 2016 11:06:51 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@xxxxxxxxxx> > > --- > > Documentation/gpu/drm-mm.rst | 11 ++++++ > > drivers/gpu/drm/Kconfig | 4 +-- > > drivers/gpu/drm/drm_gem_cma_helper.c | 69 +++++++++++++++++++++++++++++++++ > > include/drm/drm_gem_cma_helper.h | 17 +++++++++ > > 4 files changed, 99 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst > > index bca8085..6e7efab 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 GEM care provides a helper method > > s/GEM care/the GEM core/ > > > +: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 83ac815..0eae4ad 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..01016b1 100644 > > --- a/drivers/gpu/drm/drm_gem_cma_helper.c > > +++ b/drivers/gpu/drm/drm_gem_cma_helper.c > > @@ -358,6 +358,75 @@ 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. > > I would add > > "It's intended to be used as a direct handler for the :c:type:`struct > file_operations <file_operations>` .get_unmapped_area() operation." If' it's kernel-doc you can use shortcuts to autogenerate the links. Only works with kernel-doc comments though, not with .rst in general: "It's intended to be used as a direct handler for the struct &file_operations .get_unmapped_area() operation." And +1 from me on sprinkling links all over docs. We might want to do that for all the fbdev fops, for consistency. Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
