From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] drm/i915: set ctx->initialized only after RCS Date: Tue, 7 Jan 2014 08:10:33 +0100 Message-ID: <20140107071033.GB16015@phenom.ffwll.local> References: <1388266309-1178-1-git-send-email-benjamin.widawsky@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ea0-f177.google.com (mail-ea0-f177.google.com [209.85.215.177]) by gabe.freedesktop.org (Postfix) with ESMTP id 053C7FA597 for ; Mon, 6 Jan 2014 23:09:21 -0800 (PST) Received: by mail-ea0-f177.google.com with SMTP id n15so1839ead.8 for ; Mon, 06 Jan 2014 23:09:18 -0800 (PST) Content-Disposition: inline In-Reply-To: <1388266309-1178-1-git-send-email-benjamin.widawsky@intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org To: Ben Widawsky Cc: Intel GFX , Ben Widawsky List-Id: intel-gfx@lists.freedesktop.org On Sat, Dec 28, 2013 at 01:31:49PM -0800, Ben Widawsky wrote: > The initialized flag is used to specify a context has been initialized > and it's context is safe to load, ie. the 3d state is setup properly. > With full PPGTT, we emit the address space loads during context switch > and this currently marks a context as initialized. With full PPGTT > patches, if a client first emits a batch to !RCS, then later, RCS, the > code will mistake the context as initialized and try to reload an > uninitialized context. > > 1. context 1 blit // context initialized > 2. context 2 // saves context 1 random state > 3. context 1 render // loads random state from step 2 > > It is really easy to hit this with a planned upcoming patch which makes > default context reuse possible. > > NOTE: This should only effect full PPGTT branches, ie. current > drm-intel-nightly. > > Thanks to Chris for helping me track this down. > > Cc: Chris Wilson > Signed-off-by: Ben Widawsky Do we have a testcase for this or a bug report? -Daniel > --- > drivers/gpu/drm/i915/i915_gem_context.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c > index ebe0f67..28b9f30 100644 > --- a/drivers/gpu/drm/i915/i915_gem_context.c > +++ b/drivers/gpu/drm/i915/i915_gem_context.c > @@ -686,10 +686,11 @@ static int do_switch(struct intel_ring_buffer *ring, > i915_gem_context_unreference(from); > } > > + to->is_initialized = true; > + > done: > i915_gem_context_reference(to); > ring->last_context = to; > - to->is_initialized = true; > to->last_ring = ring; > > return 0; > -- > 1.8.5.2 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch