Re: [PATCH v5 5/6] drm: lcdif: Add multiple encoders and first bridges support

[Marek Vasut <marex@denx.de>]

On 5/8/23 07:57, Liu Ying wrote:
> 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.
> 
> Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> Acked-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> Signed-off-by: Liu Ying <victor.liu@nxp.com>
> ---
> v4->v5:
> * Rebase upon v6.4-rc1 and resolve a trivial conflict.
> * Add Alexander's A-b and T-b tags.
> 
> v3->v4:
> * Improve warning message when ignoring invalid LCDIF OF endpoint ids.
>    (Alexander)
> 
> 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 e816f87828fb..cf27b63b1899 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_dma.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);
> +		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) {

Can we make the maximum number of displays, or really bridge, specific 
to IP instance instead (1 for mx8mp, 3 for mx93) ? If so, then I think 
we need to track a list of bridges in some linked list or some such 
dynamic structure, which would allow us to get rid of MAX_DISPLAYS macro.

> +			dev_warn(dev, "ingoring invalid endpoint id %u\n", of_ep.id);

s@ingoring@ignoring@

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