linux-kernel - Re: [PATCH 6/7] drm/msm/A6XX: Add a flag to allow preemption to submitqueue

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Message-ID: <20240822192144.e7u3fhlqpeyypbxp@hu-akhilpo-hyd.qualcomm.com>
Date: Fri, 23 Aug 2024 00:51:44 +0530
From: Akhil P Oommen <quic_akhilpo@...cinc.com>
To: Connor Abbott <cwabbott0@...il.com>
CC: Antonino Maniscalco <antomani103@...il.com>,
        Rob Clark
	<robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        "Dmitry Baryshkov" <dmitry.baryshkov@...aro.org>,
        Marijn Suijten
	<marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, "Daniel
 Vetter" <daniel@...ll.ch>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/7] drm/msm/A6XX: Add a flag to allow preemption to
 submitqueue_create

On Tue, Aug 20, 2024 at 11:48:33AM +0100, Connor Abbott wrote:
> On Mon, Aug 19, 2024 at 9:31 PM Akhil P Oommen <quic_akhilpo@...cinc.com> wrote:
> >
> > On Thu, Aug 15, 2024 at 08:26:16PM +0200, Antonino Maniscalco wrote:
> > > Some userspace changes are necessary so add a flag for userspace to
> > > advertise support for preemption.
> >
> > So the intention is to fallback to level 0 preemption until user moves
> > to Mesa libs with level 1 support for each new GPU? Please elaborate a bit.
> >
> > -Akhil.
> 
> Yes, that's right. My Mesa series fixes L1 preemption and
> skipsaverestore by changing some of the CP_SET_MARKER calls and
> register programming and introducing CP_SET_AMBLE calls and then
> enables the flag on a7xx.

And we want to control L1 preemption per submitqueue because both
freedreno and turnip may not have support ready at the same time?

Antonino, since this is a UAPI update, it is good to have these details
captured in the commit msg for reference.

-Akhil.

> 
> Connor
> 
> >
> > >
> > > Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
> > > ---
> > >  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 12 ++++++++----
> > >  include/uapi/drm/msm_drm.h            |  5 ++++-
> > >  2 files changed, 12 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > index 1a90db5759b8..86357016db8d 100644
> > > --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> > > @@ -453,8 +453,10 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> > >       OUT_PKT7(ring, CP_SET_MARKER, 1);
> > >       OUT_RING(ring, 0x101); /* IFPC disable */
> > >
> > > -     OUT_PKT7(ring, CP_SET_MARKER, 1);
> > > -     OUT_RING(ring, 0x00d); /* IB1LIST start */
> > > +     if (submit->queue->flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT) {
> > > +             OUT_PKT7(ring, CP_SET_MARKER, 1);
> > > +             OUT_RING(ring, 0x00d); /* IB1LIST start */
> > > +     }
> > >
> > >       /* Submit the commands */
> > >       for (i = 0; i < submit->nr_cmds; i++) {
> > > @@ -485,8 +487,10 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> > >                       update_shadow_rptr(gpu, ring);
> > >       }
> > >
> > > -     OUT_PKT7(ring, CP_SET_MARKER, 1);
> > > -     OUT_RING(ring, 0x00e); /* IB1LIST end */
> > > +     if (submit->queue->flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT) {
> > > +             OUT_PKT7(ring, CP_SET_MARKER, 1);
> > > +             OUT_RING(ring, 0x00e); /* IB1LIST end */
> > > +     }
> > >
> > >       get_stats_counter(ring, REG_A7XX_RBBM_PERFCTR_CP(0),
> > >               rbmemptr_stats(ring, index, cpcycles_end));
> > > diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
> > > index 3fca72f73861..f37858db34e6 100644
> > > --- a/include/uapi/drm/msm_drm.h
> > > +++ b/include/uapi/drm/msm_drm.h
> > > @@ -345,7 +345,10 @@ struct drm_msm_gem_madvise {
> > >   * backwards compatibility as a "default" submitqueue
> > >   */
> > >
> > > -#define MSM_SUBMITQUEUE_FLAGS (0)
> > > +#define MSM_SUBMITQUEUE_ALLOW_PREEMPT        0x00000001
> > > +#define MSM_SUBMITQUEUE_FLAGS                    ( \
> > > +             MSM_SUBMITQUEUE_ALLOW_PREEMPT | \
> > > +             0)
> > >
> > >  /*
> > >   * The submitqueue priority should be between 0 and MSM_PARAM_PRIORITIES-1,
> > >
> > > --
> > > 2.46.0
> > >
> > >