On Fri, 20 Apr 2012 21:03:35 +0200, Daniel Vetter <daniel.vetter at ffwll.ch> wrote: > If we try to do that and the scanlines just wouldn't advance, we > busy-hang the machine holding the modeset mutex. Not great for > debugging. > > References: https://bugzilla.kernel.org/show_bug.cgi?id=43020 > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch> Reviewer hangs head in shame: > + if (wait_for(I915_READ(pipe_dsl_reg) >= vactive, 1000)) > + DRM_ERROR("timed out waiting for vactive in " > + "load_detect, scanline: %u\n", > + I915_READ(pipe_dsl_reg)); > + if (wait_for((dsl = I915_READ(pipe_dsl_reg)) <= vsample, 1000)) > + DRM_ERROR("timed out waiting for vsample in " > + "load_detect, scanline: %u\n", > + I915_READ(pipe_dsl_reg)); wait_for() catches us out everytime we convert and existing while(), because the predicate is when it stops. Perhaps if we had a wait_until, but anyway the fix here is: if (wait_for(I915_READ(pipe_dsl_reg) < vactive, 1000)) ... if (wait_for((dsl = I915_READ(pipe_dsl_reg)) > vsample, 1000)) ... -Chris -- Chris Wilson, Intel Open Source Technology Centre
