Several SHMEM-based drivers use the BO as shadow buffer for the real framebuffer memory. Damage handling requires a vmap of the BO memory. Vmap/vunmap can acquire the dma-buf reservation lock, which is not allowed in commit tails.
This patchset introduces a set of helpers that implement vmap/vunmap in the plane's prepare_fb and cleanup_fb; and provide the mapping's address to commit-tail functions. Wrapper sfor simple KMS are provides, as all of the involved drivers are built upon simple-KMS helpers.
Patch 1 adds the support for private plane state to the simple-KMS helper library.
Patch 2 provides plane state for SHMEM-based shadow planes. It's a DRM plane with BO mappings into kernel address space. The involved helpers take care of the details.
Patches 3 to 6 convert each involved driver to the new shadow-plane helpers. The vmap operations are being removed from commit-tail functions. An additional benefit is that vmap errors are now detected before the commit starts. The original commit-tail functions could not handle failed vmap operations.
I smoke-tested the code by running fbdev, Xorg and weston with the converted mgag200 driver.
Thomas Zimmermann (6): drm/simple-kms: Add plane-state helpers drm/shmem-helper: Add additional KMS helpers drm/mgag200: Move vmap out of commit tail drm/cirrus: Move vmap out of commit tail drm/gm12u320: Move vmap out of commit tail drm/udl: Move vmap out of commit tail
drivers/gpu/drm/Kconfig | 7 + drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_gem_shmem_kms_helper.c | 159 +++++++++++++++++++++ drivers/gpu/drm/drm_simple_kms_helper.c | 40 +++++- drivers/gpu/drm/mgag200/Kconfig | 1 + drivers/gpu/drm/mgag200/mgag200_mode.c | 25 ++-- drivers/gpu/drm/tiny/Kconfig | 6 +- drivers/gpu/drm/tiny/cirrus.c | 45 +++--- drivers/gpu/drm/tiny/gm12u320.c | 30 ++-- drivers/gpu/drm/udl/Kconfig | 1 + drivers/gpu/drm/udl/udl_modeset.c | 36 ++--- include/drm/drm_gem_shmem_kms_helper.h | 56 ++++++++ include/drm/drm_simple_kms_helper.h | 28 ++++ 13 files changed, 353 insertions(+), 82 deletions(-) create mode 100644 drivers/gpu/drm/drm_gem_shmem_kms_helper.c create mode 100644 include/drm/drm_gem_shmem_kms_helper.h
base-commit: 1e37c3960fd3910f3f65cd6927a6ebab8e8efc26 -- 2.30.0