On Fri, Dec 02, 2011 at 11:21:49PM +0100, Daniel Vetter wrote: > gpu reset is a very important piece of our infrastructure. > Unfortunately we only really it test by actually hanging the gpu, > which often has bad side-effects for the entire system. And the gpu > hang handling code is one of the rather complicated pieces of code we > have, consisting of > - hang detection > - error capture > - actual gpu reset > - reset of all the gem bookkeeping > - reinitialition of the entire gpu > > This patch adds a debugfs to selectively stopping rings by ceasing to > update the hw tail pointer, which will result in the gpu no longer > updating it's head pointer and eventually to the hangcheck firing. > This way we can exercise the gpu hang code under controlled conditions > without a dying gpu taking down the entire systems. > > Patch motivated by me forgetting to properly reinitialize ppgtt after > a gpu reset. > > Usage: > > echo $((1 << $ringnum)) > i915_ring_stop # stops one ring > > echo 0xffffffff > i915_ring_stop # stops all, future-proof version > > then run whatever testload is desired. i915_ring_stop automatically > resets after a gpu hang is detected to avoid hanging the gpu to fast > and declaring it wedged. > > v2: Incorporate feedback from Chris Wilson. > > v3: Add the missing cleanup. > > Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch> Acked-by: Ben Widawsky <ben at bwidawsk.net>
