| Message ID | 1352992849-11219-1-git-send-email-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 15 Nov 2012 16:20:49 +0100, Daniel Vetter <daniel.vetter@ffwll.ch> wrote: > Since we drop dev->struct_mutex when going through the slowpath, the > object might have been moved out of the cpu domain. Hence we need to > clflush the entire object to ensure that after the ioctl returns, > everything is coherent again (interwoven writes are ill-defined > anyway). > > But we only need to do this if we start in the cpu domain and the > object requires flushing for coherency. So don't do the flushing if > the object is coherent anyway or if we've done in-line clfushing > already. > > v2: i915_gem_clflush_object already checks whether the object is > coherent and if so, drops the flushing. Hence we don't need to check > that ourselves, simplifying the condition. > Getting clearer, certainly. How about reversing the order of the checks so that it reads as if (used-fast-path && fast-path-no-longer-valid) do_fixup()? -Chris
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index eaaf095..ab66645 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -831,8 +831,9 @@ out: if (hit_slowpath) { /* Fixup: Flush dirty cachelines in case the object isn't in the - * cpu write domain anymore. */ - if (obj->base.write_domain != I915_GEM_DOMAIN_CPU) { + * cpu write domain anymore, and we haven't flushed it manually. */ + if (obj->base.write_domain != I915_GEM_DOMAIN_CPU && + !needs_clflush_after) { i915_gem_clflush_object(obj); i915_gem_chipset_flush(dev); }
Since we drop dev->struct_mutex when going through the slowpath, the object might have been moved out of the cpu domain. Hence we need to clflush the entire object to ensure that after the ioctl returns, everything is coherent again (interwoven writes are ill-defined anyway). But we only need to do this if we start in the cpu domain and the object requires flushing for coherency. So don't do the flushing if the object is coherent anyway or if we've done in-line clfushing already. v2: i915_gem_clflush_object already checks whether the object is coherent and if so, drops the flushing. Hence we don't need to check that ourselves, simplifying the condition. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- drivers/gpu/drm/i915/i915_gem.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)