<div class="gmail_quote">On Thu, Dec 29, 2011 at 23:52, Eric Anholt <<a href="mailto:eric@anholt.net">eric@anholt.net</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> These registers are automatically incremented by the hardware during transform feedback to track where the next streamed vertex output should go. Unlike the previous generation, which had a packet for setting the corresponding registers to a defined value, gen7 only has MI_LOAD_REGISTER_IMM to do so. That's a secure packet (since it loads an arbitrary register), so we need to do it from the kernel, and it needs to be settable atomically with the batchbuffer execution so that two clients doing transform feedback don't stomp on each others' state. Instead of building a more complicated interface involcing setting the registers to a specific value, just set them to 0 when asked and userland can tweak its pointers accordingly. Signed-off-by: Eric Anholt <<a href="mailto:eric@anholt.net">eric@anholt.net</a>> </blockquote><div></div><blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> --- drivers/gpu/drm/i915/i915_dma.c | 3 ++ drivers/gpu/drm/i915/i915_gem_execbuffer.c | 31 ++++++++++++++++++++++++++++ drivers/gpu/drm/i915/i915_reg.h | 6 +++++ include/drm/i915_drm.h | 4 +++ 4 files changed, 44 insertions(+), 0 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index a9ae374..1add685 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -781,6 +781,9 @@ static int i915_getparam(struct drm_device *dev, void *data, case I915_PARAM_HAS_RELAXED_DELTA: value = 1; break; + case I915_PARAM_HAS_GEN7_SOL_RESET: + value = 1; </blockquote><div> Wouldn't it be better to have: value = IS_GEN7(dev); as it is gen7+-specific item. This way, userspace could check for this support early, and avoid setting the flag on the batchbuffer in vain on pre-gen7 architectures. Either way, it will work, so: </div></div> Reviewed-by: Eugeni Dodonov <<a href="mailto:eugeni.dodonov@intel.com">eugeni.dodonov@intel.com</a>> -- Eugeni Dodonov<a href="http://eugeni.dodonov.net/" target="_blank"> </a>