Re: [PATCH v4 3/3] drm/mediatek: Implement OF graphs support for display paths

Michael Walle
2024-05-17T09:50:01Z

[-- Attachment #1.1: Type: text/plain, Size: 6378 bytes --]

Hi Angelo,

On Thu May 16, 2024 at 10:11 AM CEST, AngeloGioacchino Del Regno wrote:
> Implement OF graphs support to the mediatek-drm drivers, allowing to
> stop hardcoding the paths, and preventing this driver to get a huge
> amount of arrays for each board and SoC combination, also paving the
> way to share the same mtk_mmsys_driver_data between multiple SoCs,
> making it more straightforward to add support for new chips.

paths might be optional, see comment in mtk_drm_kms_init(). But with
this patch, you'll get an -EINVAL with a disabled path. See my
proposals how to fix that below.

With these changes and the following two patches I was able to get
DisplayPort working on vdosys1. vdosys0 wasn't used at all.
https://lore.kernel.org/r/20240516145824.1669263-1-mwalle@kernel.org/
https://lore.kernel.org/r/20240517093024.1702750-1-mwalle@kernel.org/

I've already successfully tested a former version with DSI output on
vdosys0.

Thanks for working on this!

> +/**
> + * mtk_drm_of_ddp_path_build_one - Build a Display HW Pipeline for a CRTC Path
> + * @dev: The mediatek-drm device
> + * @cpath: CRTC Path relative to a VDO or MMSYS
> + * @out_path: Pointer to an array that will contain the new pipeline
> + * @out_path_len: Number of entries in the pipeline array
> + *
> + * MediaTek SoCs can use different DDP hardware pipelines (or paths) depending
> + * on the board-specific desired display configuration; this function walks
> + * through all of the output endpoints starting from a VDO or MMSYS hardware
> + * instance and builds the right pipeline as specified in device trees.
> + *
> + * Return:
> + * * %0 - Display HW Pipeline successfully built and validated
> + * * %-ENOENT - Display pipeline was not specified in device tree
> + * * %-EINVAL - Display pipeline built but validation failed
> + * * %-ENOMEM - Failure to allocate pipeline array to pass to the caller
> + */
> +static int mtk_drm_of_ddp_path_build_one(struct device *dev, enum mtk_crtc_path cpath,
> + const unsigned int **out_path,
> + unsigned int *out_path_len)
> +{
> + struct device_node *next, *prev, *vdo = dev->parent->of_node;
> + unsigned int temp_path[DDP_COMPONENT_DRM_ID_MAX] = { 0 };
> + unsigned int *final_ddp_path;
> + unsigned short int idx = 0;
> + bool ovl_adaptor_comp_added = false;
> + int ret;
> +
> + /* Get the first entry for the temp_path array */
> + ret = mtk_drm_of_get_ddp_ep_cid(vdo, 0, cpath, &next, &temp_path[idx]);
> + if (ret) {
> + if (next && temp_path[idx] == DDP_COMPONENT_DRM_OVL_ADAPTOR) {
> + dev_err(dev, "Adding OVL Adaptor for %pOF\n", next);
> + ovl_adaptor_comp_added = true;
> + } else {
> + if (next)
> + dev_err(dev, "Invalid component %pOF\n", next);
> + else
> + dev_err(dev, "Cannot find first endpoint for path %d\n", cpath);
> +
> + return ret;
> + }
> + }
> + idx++;
> +
> + /*
> + * Walk through port outputs until we reach the last valid mediatek-drm component.
> + * To be valid, this must end with an "invalid" component that is a display node.
> + */
> + do {
> + prev = next;
> + ret = mtk_drm_of_get_ddp_ep_cid(next, 1, cpath, &next, &temp_path[idx]);
> + of_node_put(prev);
> + if (ret) {
> + of_node_put(next);
> + break;
> + }
> +
> + /*
> + * If this is an OVL adaptor exclusive component and one of those
> + * was already added, don't add another instance of the generic
> + * DDP_COMPONENT_OVL_ADAPTOR, as this is used only to decide whether
> + * to probe that component master driver of which only one instance
> + * is needed and possible.
> + */
> + if (temp_path[idx] == DDP_COMPONENT_DRM_OVL_ADAPTOR) {
> + if (!ovl_adaptor_comp_added)
> + ovl_adaptor_comp_added = true;
> + else
> + idx--;
> + }
> + } while (++idx < DDP_COMPONENT_DRM_ID_MAX);

/* The device might not be disabled. In that case, don't check the last
* entry but just report the missing device. */
if (ret == -ENODEV)
return ret;

> +
> + /* If the last entry is not a final display output, the configuration is wrong */
> + switch (temp_path[idx - 1]) {
> + case DDP_COMPONENT_DP_INTF0:
> + case DDP_COMPONENT_DP_INTF1:
> + case DDP_COMPONENT_DPI0:
> + case DDP_COMPONENT_DPI1:
> + case DDP_COMPONENT_DSI0:
> + case DDP_COMPONENT_DSI1:
> + case DDP_COMPONENT_DSI2:
> + case DDP_COMPONENT_DSI3:
> + break;
> + default:
> + dev_err(dev, "Invalid display hw pipeline. Last component: %d (ret=%d)\n",
> + temp_path[idx - 1], ret);
> + return -EINVAL;
> + }
> +
> + final_ddp_path = devm_kmemdup(dev, temp_path, idx * sizeof(temp_path[0]), GFP_KERNEL);
> + if (!final_ddp_path)
> + return -ENOMEM;
> +
> + dev_dbg(dev, "Display HW Pipeline built with %d components.\n", idx);
> +
> + /* Pipeline built! */
> + *out_path = final_ddp_path;
> + *out_path_len = idx;
> +
> + return 0;
> +}
> +
> +static int mtk_drm_of_ddp_path_build(struct device *dev, struct device_node *node,
> + struct mtk_mmsys_driver_data *data)
> +{
> + struct device_node *ep_node;
> + struct of_endpoint of_ep;
> + bool output_present[MAX_CRTC] = { false };
> + int ret;
> +
> + for_each_endpoint_of_node(node, ep_node) {
> + ret = of_graph_parse_endpoint(ep_node, &of_ep);
> + of_node_put(ep_node);
> + if (ret) {
> + dev_err_probe(dev, ret, "Cannot parse endpoint\n");
> + break;
> + }
> +
> + if (of_ep.id >= MAX_CRTC) {
> + ret = dev_err_probe(dev, -EINVAL,
> + "Invalid endpoint%u number\n", of_ep.port);
> + break;
> + }
> +
> + output_present[of_ep.id] = true;
> + }
> +
> + if (ret)
> + return ret;
> +
> + if (output_present[CRTC_MAIN]) {
> + ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_MAIN,
> + &data->main_path, &data->main_len);
> + if (ret)
if (ret && ret != -ENODEV)

> + return ret;
> + }
> +
> + if (output_present[CRTC_EXT]) {
> + ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_EXT,
> + &data->ext_path, &data->ext_len);
> + if (ret)
likewise

> + return ret;
> + }
> +
> + if (output_present[CRTC_THIRD]) {
> + ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_THIRD,
> + &data->third_path, &data->third_len);
> + if (ret)
likewise

> + return ret;
> + }
> +
> + return 0;
> +}

-michael

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 297 bytes --]

[-- Attachment #2: Type: text/plain, Size: 176 bytes --]