Hi Dave,
I've figured a pull request is easier ;-)
Changes since the patchbomb on dri-devel: - Added a patch to adjust the new omapdrm code in 3.8-rc4, reviewed by Rob Clark on irc (hence also why the baseline of this pull is 3.8-rc4). - Slightly fixed/clarified some commit messages and fixed one spelling fail in a comment. - Sprinkled Rob's r-b tags over the patches (for drm core changes + omapdrm).
Imo the individual patches contain really detailed commit messages, so for the merge commit just a quick overview:
The aim of this locking rework is that ioctls which a compositor should be might call for every frame (set_cursor, page_flip, addfb, rmfb and getfb/create_handle) should not be able to block on kms background activities like output detection. And since each EDID read takes about 25ms (in the best case), that always means we'll drop at least one frame.
The solution is to add per-crtc locking for these ioctls, and restrict background activities to only use the global lock. Change-the-world type of events (modeset, dpms, ...) need to grab all locks.
Two tricky parts arose in the conversion: - A lot of current code assumes that a kms fb object can't disappear while holding the global lock, since the current code serializes fb destruction with it. Hence proper lifetime management using the already created refcounting for fbs need to be instantiated for all ioctls and interfaces/users.
- The rmfb ioctl removes the to-be-deleted fb from all active users. But unconditionally taking the global kms lock to do so introduces an unacceptable potential stall point. And obviously changing the userspace abi isn't on the table, either. Hence this conversion opportunistically checks whether the rmfb ioctl holds the very last reference, which guarantees that the fb isn't in active use on any crtc or plane (thanks to the conversion to the new lifetime rules using proper refcounting). Only if this is not the case will the code go through the slowpath and grab all modeset locks. Sane compositors will never hit this path and so avoid the stall, but userspace relying on these semantics will also not break.
All these cases are exercised by the newly added subtests for the i-g-t kms_flip, tested on a machine where a full detect cycle takes around 100 ms. It works, and no frames are dropped any more with these patches applied. kms_flip also contains a special case to exercise the above-describe rmfb slowpath.
Yours, Daniel
The following changes since commit 7d1f9aeff1ee4a20b1aeb377dd0f579fe9647619:
Linux 3.8-rc4 (2013-01-17 19:25:45 -0800)
are available in the git repository at:
git://people.freedesktop.org/~danvet/drm-intel drm-kms-locking
for you to fetch changes up to 57c45428f2b005e95bbc6706cd61574183ed8522:
drm/fb_helper: check whether fbcon is bound (2013-01-20 15:59:55 +0100)
---------------------------------------------------------------- Daniel Vetter (36): drm: review locking rules in drm_crtc.c drm/doc: integrate drm_crtc.c kerneldoc drm/<drivers>: reorder framebuffer init sequence drm/vmwgfx: reorder framebuffer init sequence drm/gma500: move fbcon restore to lastclose drm/nouveau: protect evo_wait/evo_kick sections with a channel mutex drm/nouveau: try to protect nbo->pin_refcount drm/<drivers>: Unified handling of unimplemented fb->create_handle drm: encapsulate crtc->set_config calls drm: add drm_modeset_lock|unlock_all drm/i915: use drm_modeset_lock_all drm/gma500: use drm_modeset_lock_all drm/ast: use drm_modeset_lock_all drm/shmobile: use drm_modeset_lock_all drm/vmwgfx: use drm_modeset_lock_all omapdrm: use modeset_lock_all drm: add per-crtc locks drm: only take the crtc lock for ->cursor_set drm: only take the crtc lock for ->cursor_move drm: revamp locking around fb creation/destruction drm: create drm_framebuffer_lookup drm: revamp framebuffer cleanup interfaces drm: reference framebuffers which are on the idr drm: nest modeset locks within fpriv->fbs_lock drm: push modeset_lock_all into ->fb_create driver callbacks drm: don't take modeset locks in getfb ioctl drm: fb refcounting for dirtyfb_ioctl drm: refcounting for sprite framebuffers drm: refcounting for crtc framebuffers drm/i915: dump refcount into framebuffer debugfs file drm/vmwgfx: add proper framebuffer refcounting drm: optimize drm_framebuffer_remove drm: only grab the crtc lock for pageflips drm: don't hold crtc mutexes for connector ->detect callbacks drm/doc: updates for new framebuffer lifetime rules drm/fb_helper: check whether fbcon is bound
Documentation/DocBook/drm.tmpl | 63 ++- drivers/gpu/drm/ast/ast_drv.c | 4 +- drivers/gpu/drm/ast/ast_drv.h | 2 + drivers/gpu/drm/ast/ast_fb.c | 1 + drivers/gpu/drm/ast/ast_main.c | 12 +- drivers/gpu/drm/cirrus/cirrus_fbdev.c | 1 + drivers/gpu/drm/cirrus/cirrus_main.c | 12 +- drivers/gpu/drm/drm_crtc.c | 792 +++++++++++++++++------------ drivers/gpu/drm/drm_fb_cma_helper.c | 15 +- drivers/gpu/drm/drm_fb_helper.c | 65 ++- drivers/gpu/drm/drm_fops.c | 1 + drivers/gpu/drm/exynos/exynos_drm_fbdev.c | 4 +- drivers/gpu/drm/gma500/framebuffer.c | 29 +- drivers/gpu/drm/gma500/psb_device.c | 8 +- drivers/gpu/drm/gma500/psb_drv.c | 14 +- drivers/gpu/drm/i2c/ch7006_drv.c | 2 +- drivers/gpu/drm/i915/i915_debugfs.c | 15 +- drivers/gpu/drm/i915/intel_display.c | 21 +- drivers/gpu/drm/i915/intel_dp.c | 2 + drivers/gpu/drm/i915/intel_fb.c | 5 +- drivers/gpu/drm/i915/intel_lvds.c | 4 +- drivers/gpu/drm/i915/intel_overlay.c | 14 +- drivers/gpu/drm/i915/intel_sprite.c | 8 +- drivers/gpu/drm/mgag200/mgag200_fb.c | 1 + drivers/gpu/drm/mgag200/mgag200_main.c | 16 +- drivers/gpu/drm/nouveau/nouveau_bo.c | 22 +- drivers/gpu/drm/nouveau/nouveau_bo.h | 2 + drivers/gpu/drm/nouveau/nouveau_display.c | 10 +- drivers/gpu/drm/nouveau/nouveau_fbcon.c | 1 + drivers/gpu/drm/nouveau/nv04_display.c | 2 +- drivers/gpu/drm/nouveau/nv17_tv.c | 2 +- drivers/gpu/drm/nouveau/nv50_display.c | 10 + drivers/gpu/drm/radeon/radeon_cursor.c | 8 +- drivers/gpu/drm/radeon/radeon_display.c | 2 +- drivers/gpu/drm/radeon/radeon_fb.c | 2 + drivers/gpu/drm/shmobile/shmob_drm_drv.c | 4 +- drivers/gpu/drm/udl/udl_fb.c | 4 +- drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 2 +- drivers/gpu/drm/vmwgfx/vmwgfx_ioctl.c | 38 +- drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 87 ++-- drivers/staging/omapdrm/omap_crtc.c | 8 +- drivers/staging/omapdrm/omap_debugfs.c | 2 + drivers/staging/omapdrm/omap_drv.c | 4 +- drivers/staging/omapdrm/omap_fb.c | 16 +- drivers/staging/omapdrm/omap_fbdev.c | 8 +- include/drm/drmP.h | 13 + include/drm/drm_crtc.h | 30 ++ 47 files changed, 836 insertions(+), 552 deletions(-)