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Message-ID: <84fdbdc7-7890-965a-bc6b-a19bd0ca4937@linaro.org>
Date: Wed, 31 Mar 2021 19:03:33 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Kalyan Thota <kalyan_t@...eaurora.org>, y@...lcomm.com,
dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, robdclark@...il.com,
dianders@...omium.org, mkrishn@...eaurora.org, hywu@...gle.com,
mka@...gle.com, midean@...gle.com, steev@...i.org
Subject: Re: [v1] drm/msm/disp/dpu1: fix warn stack reported during dpu resume
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.
>
> Reported-by: Steev Klimaszewski <steev@...i.org>
> 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
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