<div dir="ltr">Thanks for the updates! I was comparing between your code and and evdi code (eventually meant for usb displaylink), and it looks pretty similar in concept. They have some hard-coding around kernel versions for specific drm interfaces, and I can't find enough documentation to figure out if any differences matter, but thought I would pass it on to see if it is of any help: <a href="https://github.com/DisplayLink/evdi">https://github.com/DisplayLink/evdi</a></div><div class="gmail_extra"> <div class="gmail_quote">On Sun, Oct 15, 2017 at 12:30 PM, Noralf Trønnes <<a href="mailto:noralf@tronnes.org" target="_blank">noralf@tronnes.org</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This patchset adds a library for vmalloc buffer objects and makes use of it in tinydrm. The reason I want to move away from the cma helper, is that it restricts which drivers to PRIME import from, since cma requires the buffer to be physically continuous. Initially I looked at udl and decided to use shmem, but have later decided against it since shmem doesn't work with fbdev deferred I/O, they both use page->lru and page->mapping. This meant adding a shadow buffer for fbdev with increased complexity, so I fell back to the KISS principle. I'm trying to make tinydrm support drivers like simpledrm and udl, so if using vmalloc blocks those use cases, please let me know. I will do a follow up for the cma library which removes struct drm_fbdev_cma and wrappers. Noralf. Changes since version 1: - tinydrm: Remove dma_coerce_mask_and_coherent() calls (Matt Gattis) Noralf Trønnes (8): drm/fb-helper: Handle function NULL argument drm: Add drm_device->fbdev pointer drm/fb-helper: Add simple init/fini functions drm/fb-helper: Add .last_close and .output_poll_changed helpers drm/gem-fb-helper: Add drm_gem_fb_debugfs_show() drm: Add vmalloc BO helper drm/tinydrm: Use drm_vmalloc_bo drm/tinydrm: Relax buffer line prefetch Documentation/gpu/drm-kms-helpers.rst | 12 + drivers/gpu/drm/Kconfig | 7 + drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_fb_helper.c | 223 +++++++++++++++++- drivers/gpu/drm/drm_gem_framebuffer_helper.c | 45 ++++ drivers/gpu/drm/drm_vmalloc_bo_helper.c | 305 +++++++++++++++++++++++++ drivers/gpu/drm/tinydrm/Kconfig | 2 +- drivers/gpu/drm/tinydrm/core/tinydrm-core.c | 134 +++-------- drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 56 +++-- drivers/gpu/drm/tinydrm/mi0283qt.c | 8 +- drivers/gpu/drm/tinydrm/mipi-dbi.c | 31 +-- drivers/gpu/drm/tinydrm/repaper.c | 21 +- drivers/gpu/drm/tinydrm/st7586.c | 14 +- include/drm/drm_device.h | 8 + include/drm/drm_fb_helper.h | 32 +++ include/drm/drm_gem_framebuffer_helper.h | 6 + include/drm/drm_vmalloc_bo_helper.h | 88 +++++++ include/drm/tinydrm/mipi-dbi.h | 2 + include/drm/tinydrm/tinydrm.h | 38 +-- 19 files changed, 811 insertions(+), 222 deletions(-) create mode 100644 drivers/gpu/drm/drm_vmalloc_bo_helper.c create mode 100644 include/drm/drm_vmalloc_bo_helper.h -- 2.14.2 </blockquote></div> </div>