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

From: Alexander Stein
Date: Wed Feb 15 2023 - 02:54:59 EST


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@xxxxxxx>
> ---
> 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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