[Mesa-dev] [PATCH v6.2] egl: Allow creation of per surface out fence

Fri Sep 8 13:47:33 UTC 2017

Hello Folks,

Sorry for late reply, I took quite some time to CTS up, comments below.

> -----Original Message-----
> From: mesa-dev [mailto:mesa-dev-bounces at lists.freedesktop.org] On Behalf
> Of Marathe, Yogesh
> Sent: Friday, September 1, 2017 10:16 AM
> To: Tomasz Figa <tfiga at chromium.org>
> Cc: Gao, Shuo <shuo.gao at intel.com>; Liu, Zhiquan <zhiquan.liu at intel.com>;
> daniels at collabora.com; nicolai.haehnle at amd.com; Antognolli, Rafael
> <rafael.antognolli at intel.com>; eric at engestrom.ch; Emil Velikov
> <emil.l.velikov at gmail.com>; Wu, Zhongmin <zhongmin.wu at intel.com>;
> kenneth at whitecape.org; Kondapally, Kalyan <kalyan.kondapally at intel.com>;
> fernetmenta at online.de; mesa-dev at lists.freedesktop.org;
> tarceri at itsqueeze.com; varad.gautam at collabora.com
> Subject: Re: [Mesa-dev] [PATCH v6.2] egl: Allow creation of per surface out
> fence
> 
> Tomasz,
> 
> > -----Original Message-----
> > From: mesa-dev [mailto:mesa-dev-bounces at lists.freedesktop.org] On
> > Behalf Of Tomasz Figa
> > Sent: Friday, September 1, 2017 9:53 AM
> > To: Marathe, Yogesh <yogesh.marathe at intel.com>
> > On Thu, Aug 31, 2017 at 2:18 AM, Marathe, Yogesh
> > <yogesh.marathe at intel.com> wrote:
> > >> -----Original Message-----
> > >> From: mesa-dev [mailto:mesa-dev-bounces at lists.freedesktop.org] On
> > >> Behalf Of Emil Velikov
> > >> Sent: Wednesday, August 30, 2017 9:44 PM
> > >> To: Marathe, Yogesh <yogesh.marathe at intel.com>
> > >> Cc: Gao, Shuo <shuo.gao at intel.com>; Liu, Zhiquan
> > >> <zhiquan.liu at intel.com>; daniels at collabora.com;
> > >> nicolai.haehnle at amd.com; Antognolli, Rafael
> > >> <rafael.antognolli at intel.com>; eric at engestrom.ch; Wu, Zhongmin
> > >> <zhongmin.wu at intel.com>; tfiga at chromium.org;
> kenneth at whitecape.org;
> > >> Kondapally, Kalyan <kalyan.kondapally at intel.com>;
> > >> fernetmenta at online.de; mesa-dev at lists.freedesktop.org;
> > >> tarceri at itsqueeze.com; varad.gautam at collabora.com
> > >> Subject: Re: [Mesa-dev] [PATCH v6.2] egl: Allow creation of per
> > >> surface out fence
> > >>
> > >> On 30 August 2017 at 15:39, Marathe, Yogesh
> > >> <yogesh.marathe at intel.com>
> > >> wrote:
> > >>
> > >> >
> > >> > Thank you, Tomasz and all involved for the help and guidance.
> > >> >
> > >> Our excitement was short lived - see commit
> > >> 8c9df0daf20206fafb7df77b1edcbc41b8e91372.
> > >>
> > >> Seems the patch was not run through the Intel CI, though I'm should
> > >> not have assumed that you're aware of if.
> > >> Please get in touch with Mark Janes (Cc'd here, janesma on IRC). He
> > >> can set you up and/or run a branch for you.
> > >>
> > >
> > > No problem. I will contact Mark.
> > >
> > > Primarily looks like platform / kernel version issue.
> > > intel_get_boolean() for I915_PARAM_HAS_EXEC_FENCE is false, but I
> > > see following in i915_drv.c:915_getparam in kernel, no clue why that
> > > would come false in UMD.
> > >
> > > ...
> > >         case I915_PARAM_HAS_EXEC_FENCE:
> > >                 /* For the time being all of these are always true;
> > >                  * if some supported hardware does not have one of these
> > >                  * features this value needs to be provided from
> > >                  * INTEL_INFO(), a feature macro, or similar.
> > >                  */
> > >                 value = 1;
> > >                 break;
> > > ...
> >
> > Which kernel are you looking at? Remember that not everyone uses
> > current upstream master. There is a number of upstream stable releases
> > and downstream forks. Grepping for I915_PARAM_HAS_EXEC_FENCE on
> > http://elixir.free-electrons.com, shows that it was only added in Linux 4.12.
> >
> 
> I'm on 4.9.x but I see my kernel  tree has following patch, so this looks like it is
> done for android (cherry picked / backport). That’s why it worked for me always!
> 
> commit f0683754f03fa308a2657cb1dadbf235c9607188
> Author: Chris Wilson <chris at chris-wilson.co.uk>
> Date:   Fri Jan 27 09:40:08 2017 +0000
> 
>     drm/i915: Support explicit fencing for execbuf
> 
> Nonetheless, as you mentioned, I've synced up with Mark and we've created a
> separate branch where CTS / intel mesa CI can run. Let me try to fix this.
> 
> Caveat: To have flatland running on android  there was another issue in kernel
> which needed a fix. Details -
> https://bugs.freedesktop.org/show_bug.cgi?id=101656

I was able to run CTS (https://github.com/KhronosGroup/VK-GL-CTS) on this patch
for x11_egl. I see exact same results before and after patch on Ubuntu 16.04 setup. 
Mark had also mentioned  this works fine on 4.12 onwards (essentially with drm/i915: 
Support explicit fencing for execbuf patch in kernel).

Regarding the primary reason why this was reverted

mesa/drivers/dri/i965/brw_sync.c:491: brw_dri_create_fence_fd:
Assertion `brw->screen->has_exec_fence' failed.

This assertion evident on older kernels. Although I'm bit surprised here after looking at
the code. Older kernels where this explicit fencing is not supported must've returned
'false' for has_exec_fence in intelInitScreen2(). 

   screen->has_exec_fence =
     intel_get_boolean(screen, I915_PARAM_HAS_EXEC_FENCE); 

It appears that’s coming 'true' and due to that we set enable_out_fence in dri2_init_surface()
(based on get_capabilities()) which causes create_fence_fd call on non-supported kernels. 
Isn't this strange? Can someone please comment?

Regards,
Yogesh.

> 
> > Best regards,
> > Tomasz
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