Re: [DPU PATCH 1/4] drm/msm/dpu: add atomic private object to dpu kms

[Jordan Crouse <jcrouse-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

On Tue, Jun 12, 2018 at 06:17:44PM -0700, Jeykumar Sankaran wrote:
> Subclass drm private state for DPU for handling driver
> specific data. Adds atomic private object and private object
> lock to dpu kms. Provides helper function to retrieve DPU
> private data from current atomic state.
> 
> Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 66 +++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h | 15 ++++++++
>  2 files changed, 81 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> index fe614c0..a4ab783 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> @@ -1076,6 +1076,10 @@ static void dpu_kms_destroy(struct msm_kms *kms)
>  
>  	dpu_kms = to_dpu_kms(kms);
>  	_dpu_kms_hw_destroy(dpu_kms);
> +
> +	drm_atomic_private_obj_fini(&dpu_kms->priv_obj);
> +	drm_modeset_lock_fini(&dpu_kms->priv_obj_lock);
> +
>  }
>  
>  static void dpu_kms_preclose(struct msm_kms *kms, struct drm_file *file)
> @@ -1618,10 +1622,59 @@ static int dpu_kms_hw_init(struct msm_kms *kms)
>  	return rc;
>  }
>  
> +struct dpu_private_state *dpu_get_private_state(struct drm_atomic_state *state)
> +{
> +	struct msm_drm_private *priv = state->dev->dev_private;
> +	struct dpu_kms *dpu_kms = to_dpu_kms(priv->kms);
> +	struct drm_private_state *priv_state;
> +	int rc = 0;
> +
> +	rc = drm_modeset_lock(&dpu_kms->priv_obj_lock, state->acquire_ctx);
> +	if (rc)
> +		return ERR_PTR(rc);
> +
> +	priv_state = drm_atomic_get_private_obj_state(state,
> +			&dpu_kms->priv_obj);
> +	if (!priv_state)
> +		return NULL;

I'll have to see later when this function is used, but I generally don't like it
when functions return both ERR_PTR and NULL on error but I'm leaving open the
possibility that this could NULL for legitimate reasons. If not, please convert
to a ERR_PTR.

> +	return to_dpu_private_state(priv_state);
> +}
> +
> +static struct drm_private_state *
> +dpu_private_obj_duplicate_state(struct drm_private_obj *obj)
> +{
> +	struct dpu_private_state *dpu_priv_state;
> +
> +	dpu_priv_state = kmemdup(obj->state,
> +			sizeof(*dpu_priv_state), GFP_KERNEL);
> +	if (!dpu_priv_state)
> +		return NULL;
> +
> +	__drm_atomic_helper_private_obj_duplicate_state(obj,
> +			&dpu_priv_state->base);
> +
> +	return &dpu_priv_state->base;
> +}
> +
> +static void dpu_private_obj_destroy_state(struct drm_private_obj *obj,
> +				      struct drm_private_state *state)
> +{
> +	struct dpu_private_state *dpu_priv_state = to_dpu_private_state(state);
> +
> +	kfree(dpu_priv_state);
> +}
> +
> +static const struct drm_private_state_funcs priv_obj_funcs = {
> +	.atomic_duplicate_state = dpu_private_obj_duplicate_state,
> +	.atomic_destroy_state = dpu_private_obj_destroy_state,
> +};
> +
>  struct msm_kms *dpu_kms_init(struct drm_device *dev)
>  {
>  	struct msm_drm_private *priv;
>  	struct dpu_kms *dpu_kms;
> +	struct dpu_private_state *dpu_priv_state;
>  	int irq;
>  
>  	if (!dev || !dev->dev_private) {
> @@ -1639,6 +1692,19 @@ struct msm_kms *dpu_kms_init(struct drm_device *dev)
>  	}
>  	dpu_kms->base.irq = irq;
>  
> +	/* Initialize private obj's */
> +	drm_modeset_lock_init(&dpu_kms->priv_obj_lock);
> +
> +	dpu_priv_state = kzalloc(sizeof(*dpu_priv_state), GFP_KERNEL);
> +	if (!dpu_priv_state) {
> +		DPU_ERROR("failed to allocate dpu priv obj\n");

We don't need an error message on memory failure - you will have no problem
identifying when this went boom if it goes boom.

> +		return ERR_PTR(-ENOMEM);
> +	}
> +
> +	drm_atomic_private_obj_init(&dpu_kms->priv_obj,
> +				    &dpu_priv_state->base,
> +				    &priv_obj_funcs);
> +
>  	return &dpu_kms->base;
>  }
>  
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> index 046e6f7..924d8967 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
> @@ -190,6 +190,9 @@ struct dpu_kms {
>  	struct dpu_hw_vbif *hw_vbif[VBIF_MAX];
>  	struct dpu_hw_mdp *hw_mdp;
>  
> +	struct drm_modeset_lock priv_obj_lock;
> +	struct drm_private_obj priv_obj;
> +
>  	bool has_danger_ctrl;
>  
>  	struct platform_device *pdev;
> @@ -197,12 +200,24 @@ struct dpu_kms {
>  	struct dss_module_power mp;
>  };
>  
> +struct dpu_private_state {
> +	struct drm_private_state base;
> +};
> +
>  struct vsync_info {
>  	u32 frame_count;
>  	u32 line_count;
>  };
>  
>  #define to_dpu_kms(x) container_of(x, struct dpu_kms, base)
> +#define to_dpu_private_state(x) container_of(x, struct dpu_private_state, base)
> +
> +/**
> + * dpu_get_private_state - get dpu private state from atomic state
> + * @state: drm atomic state
> + * Return: pointer to dpu private state object
> + */
> +struct dpu_private_state *dpu_get_private_state(struct drm_atomic_state *state);
>  
>  /**
>   * dpu_is_custom_client - whether or not to enable non-standard customizations
> -- 

-- 
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