Re: [PATCH v3 5/6] drm: lcdif: Add multiple encoders and first bridges support

[Alexander Stein <alexander.stein@ew.tq-group.com>]

Hi Liu,

thanks for the update.

Am Montag, 13. Februar 2023, 09:56:11 CET schrieb Liu Ying:
> The single LCDIF embedded in i.MX93 SoC may drive multiple displays
> simultaneously.  Look at LCDIF output port's remote port parents to
> find all enabled first bridges.  Add an encoder for each found bridge
> and attach the bridge to the encoder.  This is a preparation for
> adding i.MX93 LCDIF support.
> 
> Signed-off-by: Liu Ying <victor.liu@nxp.com>
> ---
> v2->v3:
> * No change.
> 
> v1->v2:
> * Split from patch 2/2 in v1. (Marek, Alexander)
> * Drop '!remote ||' from lcdif_attach_bridge(). (Lothar)
> * Drop unneeded 'bridges' member from lcdif_drm_private structure.
> 
>  drivers/gpu/drm/mxsfb/lcdif_drv.c | 68 +++++++++++++++++++++++++++----
>  drivers/gpu/drm/mxsfb/lcdif_drv.h |  4 +-
>  drivers/gpu/drm/mxsfb/lcdif_kms.c | 21 ++--------
>  3 files changed, 66 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> b/drivers/gpu/drm/mxsfb/lcdif_drv.c index b5b9a8e273c6..eb6c265fa2fe 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> @@ -9,13 +9,16 @@
>  #include <linux/dma-mapping.h>
>  #include <linux/io.h>
>  #include <linux/module.h>
> +#include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/of_graph.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> 
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
>  #include <drm/drm_drv.h>
> +#include <drm/drm_encoder.h>
>  #include <drm/drm_fbdev_generic.h>
>  #include <drm/drm_gem_dma_helper.h>
>  #include <drm/drm_gem_framebuffer_helper.h>
> @@ -38,19 +41,68 @@ static const struct drm_mode_config_helper_funcs
> lcdif_mode_config_helpers = { .atomic_commit_tail =
> drm_atomic_helper_commit_tail_rpm,
>  };
> 
> +static const struct drm_encoder_funcs lcdif_encoder_funcs = {
> +	.destroy = drm_encoder_cleanup,
> +};
> +
>  static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
>  {
> -	struct drm_device *drm = lcdif->drm;
> +	struct device *dev = lcdif->drm->dev;
> +	struct device_node *ep;
>  	struct drm_bridge *bridge;
>  	int ret;
> 
> -	bridge = devm_drm_of_get_bridge(drm->dev, drm->dev->of_node, 0, 0);
> -	if (IS_ERR(bridge))
> -		return PTR_ERR(bridge);
> -
> -	ret = drm_bridge_attach(&lcdif->encoder, bridge, NULL, 0);
> -	if (ret)
> -		return dev_err_probe(drm->dev, ret, "Failed to attach 
bridge\n");
> +	for_each_endpoint_of_node(dev->of_node, ep) {
> +		struct device_node *remote;
> +		struct of_endpoint of_ep;
> +		struct drm_encoder *encoder;
> +
> +		remote = of_graph_get_remote_port_parent(ep);

Is it possible for remote to be NULL?

> +		if (!of_device_is_available(remote)) {
> +			of_node_put(remote);
> +			continue;
> +		}
> +		of_node_put(remote);
> +
> +		ret = of_graph_parse_endpoint(ep, &of_ep);
> +		if (ret < 0) {
> +			dev_err(dev, "Failed to parse endpoint %pOF\n", 
ep);
> +			of_node_put(ep);
> +			return ret;
> +		}
> +
> +		if (of_ep.id >= MAX_DISPLAYS) {
> +			dev_warn(dev, "invalid endpoint id %u\n", 
of_ep.id);

I would write
dev_warn(dev, "ignoring invalid endpoint id %u\n", of_ep.id);
just because the parsing continues but this one is skipped.

> +			continue;
> +		}
> +
> +		bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 
of_ep.id);
> +		if (IS_ERR(bridge)) {
> +			of_node_put(ep);
> +			return dev_err_probe(dev, PTR_ERR(bridge),
> +					     "Failed to get bridge 
for endpoint%u\n",
> +					     of_ep.id);
> +		}
> +
> +		encoder = &lcdif->encoders[of_ep.id];
> +		encoder->possible_crtcs = drm_crtc_mask(&lcdif->crtc);
> +		ret = drm_encoder_init(lcdif->drm, encoder, 
&lcdif_encoder_funcs,
> +				       DRM_MODE_ENCODER_NONE, NULL);
> +		if (ret) {
> +			dev_err(dev, "Failed to initialize encoder for 
endpoint%u: %d\n",
> +				of_ep.id, ret);
> +			of_node_put(ep);
> +			return ret;
> +		}
> +
> +		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> +		if (ret) {
> +			of_node_put(ep);
> +			return dev_err_probe(dev, ret,
> +					     "Failed to attach 
bridge for endpoint%u\n",
> +					     of_ep.id);
> +		}

Admittedly I'm not used to the drm API, but do we need to some manual cleanup/
revert if some endpoints is e.g. deferred, but previous endpoints already have 
been successfully added? e.g. endpoint 0 is added, but adding endpoint 1 
fails.

Best regards,
Alexander

> +	}
> 
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.h
> b/drivers/gpu/drm/mxsfb/lcdif_drv.h index aa6d099a1897..c7400bd9bbd9 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_drv.h
> +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.h
> @@ -14,6 +14,8 @@
>  #include <drm/drm_encoder.h>
>  #include <drm/drm_plane.h>
> 
> +#define MAX_DISPLAYS	3
> +
>  struct clk;
> 
>  struct lcdif_drm_private {
> @@ -30,7 +32,7 @@ struct lcdif_drm_private {
>  		/* i.MXRT does support overlay planes, add them here. */
>  	} planes;
>  	struct drm_crtc			crtc;
> -	struct drm_encoder		encoder;
> +	struct drm_encoder		encoders[MAX_DISPLAYS];
>  };
> 
>  static inline struct lcdif_drm_private *
> diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> b/drivers/gpu/drm/mxsfb/lcdif_kms.c index 4ea3d2b2cf61..5f34d01e133e 100644
> --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> @@ -654,14 +654,6 @@ static const struct drm_crtc_funcs lcdif_crtc_funcs = {
> .disable_vblank = lcdif_crtc_disable_vblank,
>  };
> 
> -/*
> ---------------------------------------------------------------------------
> -- - * Encoder
> - */
> -
> -static const struct drm_encoder_funcs lcdif_encoder_funcs = {
> -	.destroy = drm_encoder_cleanup,
> -};
> -
>  /*
> ---------------------------------------------------------------------------
> -- * Planes
>   */
> @@ -754,7 +746,6 @@ int lcdif_kms_init(struct lcdif_drm_private *lcdif)
>  					BIT(DRM_COLOR_YCBCR_BT2020);
>  	const u32 supported_ranges = BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
>  				     BIT(DRM_COLOR_YCBCR_FULL_RANGE);
> -	struct drm_encoder *encoder = &lcdif->encoder;
>  	struct drm_crtc *crtc = &lcdif->crtc;
>  	int ret;
> 
> @@ -778,13 +769,7 @@ int lcdif_kms_init(struct lcdif_drm_private *lcdif)
>  		return ret;
> 
>  	drm_crtc_helper_add(crtc, &lcdif_crtc_helper_funcs);
> -	ret = drm_crtc_init_with_planes(lcdif->drm, crtc,
> -					&lcdif->planes.primary, 
NULL,
> -					&lcdif_crtc_funcs, NULL);
> -	if (ret)
> -		return ret;
> -
> -	encoder->possible_crtcs = drm_crtc_mask(crtc);
> -	return drm_encoder_init(lcdif->drm, encoder, &lcdif_encoder_funcs,
> -				DRM_MODE_ENCODER_NONE, NULL);
> +	return drm_crtc_init_with_planes(lcdif->drm, crtc,
> +					 &lcdif->planes.primary, 
NULL,
> +					 &lcdif_crtc_funcs, NULL);
>  }


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