linux-kernel - Re: [Freedreno] [PATCH 1/2] drm/msm: Add a GPU-wide wait queue

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Message-ID: <CAJs_Fx6e1LjjdHDxKVKzw+PZx5P6xiVjDCdb0iP0mnkUd4gitA@mail.gmail.com>
Date:   Mon, 13 Jan 2020 10:23:42 -0800
From:   Rob Clark <robdclark@...omium.org>
To:     Brian Ho <brian@...ho.com>,
        freedreno <freedreno@...ts.freedesktop.org>,
        robdclark@...omium.org, David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DRM DRIVER FOR MSM ADRENO GPU" 
        <dri-devel@...ts.freedesktop.org>, Rob Clark <robdclark@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Kristian Kristensen <hoegsberg@...omium.org>,
        Sean Paul <sean@...rly.run>
Subject: Re: [Freedreno] [PATCH 1/2] drm/msm: Add a GPU-wide wait queue

On Mon, Jan 13, 2020 at 9:55 AM Jordan Crouse <jcrouse@...eaurora.org> wrote:
>
> On Mon, Jan 13, 2020 at 10:36:04AM -0500, Brian Ho wrote:
> > This wait queue is signaled on all IRQs for a given GPU and will be
> > used as part of the new MSM_WAIT_IOVA ioctl so userspace can sleep
> > until the value at a given iova reaches a certain condition.
> >
> > Signed-off-by: Brian Ho <brian@...ho.com>
> > ---
> >  drivers/gpu/drm/msm/msm_gpu.c | 4 ++++
> >  drivers/gpu/drm/msm/msm_gpu.h | 3 +++
> >  2 files changed, 7 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> > index a052364a5d74..d7310c1336e5 100644
> > --- a/drivers/gpu/drm/msm/msm_gpu.c
> > +++ b/drivers/gpu/drm/msm/msm_gpu.c
> > @@ -779,6 +779,8 @@ void msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit,
> >  static irqreturn_t irq_handler(int irq, void *data)
> >  {
> >       struct msm_gpu *gpu = data;
> > +     wake_up_all(&gpu->event);
> > +
>
> I suppose it is intentional to have this happen on *all* interrupts because you
> might be using the CP interrupts for fun and profit and you don't want to plumb
> in callbacks?  I suppose it is okay to do this for all interrupts (including
> errors) but if we're spending a lot of time here we might want to only trigger
> on certain IRQs.

Was just talking to Kristian about GPU hangs.. and I suspect we might
want the ioctl to return an error if there is a gpu reset (so that
userspace can use the robustness uapi to test if the gpu reset was
something it cares about, etc)

Which is as good as a reason as I can think of the wake_up_all() on all irqs..

BR,
-R

>
> >       return gpu->funcs->irq(gpu);
> >  }
> >
> > @@ -871,6 +873,8 @@ int msm_gpu_init(struct drm_device *drm, struct platform_device *pdev,
> >
> >       spin_lock_init(&gpu->perf_lock);
> >
> > +     init_waitqueue_head(&gpu->event);
> > +
> >
> >       /* Map registers: */
> >       gpu->mmio = msm_ioremap(pdev, config->ioname, name);
> > diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> > index ab8f0f9c9dc8..60562f065dbc 100644
> > --- a/drivers/gpu/drm/msm/msm_gpu.h
> > +++ b/drivers/gpu/drm/msm/msm_gpu.h
> > @@ -104,6 +104,9 @@ struct msm_gpu {
> >
> >       struct msm_gem_address_space *aspace;
> >
> > +     /* GPU-wide wait queue that is signaled on all IRQs */
> > +     wait_queue_head_t event;
> > +
> >       /* Power Control: */
> >       struct regulator *gpu_reg, *gpu_cx;
> >       struct clk_bulk_data *grp_clks;
> > --
> > 2.25.0.rc1.283.g88dfdc4193-goog
> >
> > _______________________________________________
> > Freedreno mailing list
> > Freedreno@...ts.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/freedreno
>
> --
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project

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