linux-kernel - Re: [v1] drm/msm/disp/dpu1: fix warn stack reported during dpu resume

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Message-ID: <CAF6AEGt_aAq4dF9QkS9uJ7vwvGeR42oToCQKpsWCrfuhy_j+pw@mail.gmail.com>
Date:   Wed, 31 Mar 2021 15:47:10 -0700
From:   Rob Clark <robdclark@...il.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Kalyan Thota <kalyan_t@...eaurora.org>
Cc:     y@...lcomm.com, dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Krishna Manikandan <mkrishn@...eaurora.org>,
        Daniel Hung-yu Wu <hywu@...gle.com>, mka@...gle.com,
        Michelle Dean <midean@...gle.com>,
        Steev Klimaszewski <steev@...i.org>
Subject: Re: [v1] drm/msm/disp/dpu1: fix warn stack reported during dpu resume

On Wed, Mar 31, 2021 at 9:03 AM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On 31/03/2021 14:27, Kalyan Thota wrote:
> > WARN_ON was introduced by the below commit to catch runtime resumes
> > that are getting triggered before icc path was set.
> >
> > "drm/msm/disp/dpu1: icc path needs to be set before dpu runtime resume"
> >
> > For the targets where the bw scaling is not enabled, this WARN_ON is
> > a false alarm. Fix the WARN condition appropriately.
>
> Should we change all DPU targets to use bw scaling to the mdp from the
> mdss nodes? The limitation to sc7180 looks artificial.

yes, we should, this keeps biting us on 845

> >
> > Reported-by: Steev Klimaszewski <steev@...i.org>

Please add Fixes: tag as well

> > Signed-off-by: Kalyan Thota <kalyan_t@...eaurora.org>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c  |  8 +++++---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h  |  9 +++++++++
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c | 11 ++++++-----
> >   3 files changed, 20 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > index cab387f..0071a4d 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > @@ -294,6 +294,9 @@ static int dpu_kms_parse_data_bus_icc_path(struct dpu_kms *dpu_kms)
> >       struct icc_path *path1;
> >       struct drm_device *dev = dpu_kms->dev;
> >
> > +     if (!dpu_supports_bw_scaling(dev))
> > +             return 0;
> > +
> >       path0 = of_icc_get(dev->dev, "mdp0-mem");
> >       path1 = of_icc_get(dev->dev, "mdp1-mem");
> >
> > @@ -934,8 +937,7 @@ static int dpu_kms_hw_init(struct msm_kms *kms)
> >               DPU_DEBUG("REG_DMA is not defined");
> >       }
> >
> > -     if (of_device_is_compatible(dev->dev->of_node, "qcom,sc7180-mdss"))
> > -             dpu_kms_parse_data_bus_icc_path(dpu_kms);
> > +     dpu_kms_parse_data_bus_icc_path(dpu_kms);
> >
> >       pm_runtime_get_sync(&dpu_kms->pdev->dev);
> >
> > @@ -1198,7 +1200,7 @@ static int __maybe_unused dpu_runtime_resume(struct device *dev)
> >
> >       ddev = dpu_kms->dev;
> >
> > -     WARN_ON(!(dpu_kms->num_paths));
> > +     WARN_ON((dpu_supports_bw_scaling(ddev) && !dpu_kms->num_paths));
> >       /* Min vote of BW is required before turning on AXI clk */
> >       for (i = 0; i < dpu_kms->num_paths; i++)
> >               icc_set_bw(dpu_kms->path[i], 0, Bps_to_icc(MIN_IB_BW));
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> > index d6717d6..f7bcc0a 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> > @@ -154,6 +154,15 @@ struct vsync_info {
> >
> >   #define to_dpu_global_state(x) container_of(x, struct dpu_global_state, base)
> >
> > +/**
> > + * dpu_supports_bw_scaling: returns true for drivers that support bw scaling.
> > + * @dev: Pointer to drm_device structure
> > + */
> > +static inline int dpu_supports_bw_scaling(struct drm_device *dev)
> > +{
> > +     return of_device_is_compatible(dev->dev->of_node, "qcom,sc7180-mdss");
> > +}
> > +
> >   /* Global private object state for tracking resources that are shared across
> >    * multiple kms objects (planes/crtcs/etc).
> >    */
> > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c
> > index cd40788..8cd712c 100644
> > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c
> > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_mdss.c
> > @@ -41,6 +41,9 @@ static int dpu_mdss_parse_data_bus_icc_path(struct drm_device *dev,
> >       struct icc_path *path0 = of_icc_get(dev->dev, "mdp0-mem");
> >       struct icc_path *path1 = of_icc_get(dev->dev, "mdp1-mem");
> >
> > +     if (dpu_supports_bw_scaling(dev))
> > +             return 0;
> > +
> >       if (IS_ERR_OR_NULL(path0))
> >               return PTR_ERR_OR_ZERO(path0);
> >
> > @@ -276,11 +279,9 @@ int dpu_mdss_init(struct drm_device *dev)
> >
> >       DRM_DEBUG("mapped mdss address space @%pK\n", dpu_mdss->mmio);
> >
> > -     if (!of_device_is_compatible(dev->dev->of_node, "qcom,sc7180-mdss")) {
> > -             ret = dpu_mdss_parse_data_bus_icc_path(dev, dpu_mdss);
> > -             if (ret)
> > -                     return ret;
> > -     }
> > +     ret = dpu_mdss_parse_data_bus_icc_path(dev, dpu_mdss);
> > +     if (ret)
> > +             return ret;
> >
> >       mp = &dpu_mdss->mp;
> >       ret = msm_dss_parse_clock(pdev, mp);
> >
>
>
> --
> With best wishes
> Dmitry