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From:   Rob Clark <robdclark@gmail.com>
Date:   Fri, 3 Mar 2023 07:43:19 -0800
Message-ID: <CAF6AEGuvrZs6+9c+bUPaUpZx85Xa-R-oDjFNbC8XRbMd7rvGpA@mail.gmail.com>
Subject: Re: [PATCH v9 15/15] drm/i915: Add deadline based boost support
To:     =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>
Cc:     Rob Clark <robdclark@chromium.org>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@intel.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <ckoenig.leichtzumerken@gmail.com>,
        =?UTF-8?Q?Michel_D=C3=A4nzer?= <michel@daenzer.net>,
        open list <linux-kernel@vger.kernel.org>,
        dri-devel@lists.freedesktop.org,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        "moderated list:DMA BUFFER SHARING FRAMEWORK" 
        <linaro-mm-sig@lists.linaro.org>,
        Pekka Paalanen <ppaalanen@gmail.com>,
        Luben Tuikov <luben.tuikov@amd.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Matt Turner <mattst88@gmail.com>,
        freedreno@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
        Sumit Semwal <sumit.semwal@linaro.org>,
        "open list:DMA BUFFER SHARING FRAMEWORK" 
        <linux-media@vger.kernel.org>
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On Fri, Mar 3, 2023 at 7:20 AM Ville Syrj=C3=A4l=C3=A4
<ville.syrjala@linux.intel.com> wrote:
>
> On Fri, Mar 03, 2023 at 05:00:03PM +0200, Ville Syrj=C3=A4l=C3=A4 wrote:
> > On Fri, Mar 03, 2023 at 06:48:43AM -0800, Rob Clark wrote:
> > > On Fri, Mar 3, 2023 at 1:58 AM Tvrtko Ursulin
> > > <tvrtko.ursulin@linux.intel.com> wrote:
> > > >
> > > >
> > > > On 03/03/2023 03:21, Rodrigo Vivi wrote:
> > > > > On Thu, Mar 02, 2023 at 03:53:37PM -0800, Rob Clark wrote:
> > > > >> From: Rob Clark <robdclark@chromium.org>
> > > > >>
> > > > >
> > > > > missing some wording here...
> > > > >
> > > > >> v2: rebase
> > > > >>
> > > > >> Signed-off-by: Rob Clark <robdclark@chromium.org>
> > > > >> ---
> > > > >>   drivers/gpu/drm/i915/i915_request.c | 20 ++++++++++++++++++++
> > > > >>   1 file changed, 20 insertions(+)
> > > > >>
> > > > >> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/d=
rm/i915/i915_request.c
> > > > >> index 7503dcb9043b..44491e7e214c 100644
> > > > >> --- a/drivers/gpu/drm/i915/i915_request.c
> > > > >> +++ b/drivers/gpu/drm/i915/i915_request.c
> > > > >> @@ -97,6 +97,25 @@ static bool i915_fence_enable_signaling(struc=
t dma_fence *fence)
> > > > >>      return i915_request_enable_breadcrumb(to_request(fence));
> > > > >>   }
> > > > >>
> > > > >> +static void i915_fence_set_deadline(struct dma_fence *fence, kt=
ime_t deadline)
> > > > >> +{
> > > > >> +    struct i915_request *rq =3D to_request(fence);
> > > > >> +
> > > > >> +    if (i915_request_completed(rq))
> > > > >> +            return;
> > > > >> +
> > > > >> +    if (i915_request_started(rq))
> > > > >> +            return;
> > > > >
> > > > > why do we skip the boost if already started?
> > > > > don't we want to boost the freq anyway?
> > > >
> > > > I'd wager Rob is just copying the current i915 wait boost logic.
> > >
> > > Yup, and probably incorrectly.. Matt reported fewer boosts/sec
> > > compared to your RFC, this could be the bug
> >
> > I don't think i915 calls drm_atomic_helper_wait_for_fences()
> > so that could explain something.
>
> Oh, I guess this wasn't even supposed to take over the current
> display boost stuff since you didn't remove the old one.

Right, I didn't try to replace the current thing.. but hopefully at
least make it possible for i915 to use more of the atomic helpers in
the future

BR,
-R

> The current one just boosts after a missed vblank. The deadline
> could use your timer approach I suppose and boost already a bit
> earlier in the hopes of not missing the vblank.
>
> --
> Ville Syrj=C3=A4l=C3=A4
> Intel