Re: [PATCH 5/5] drm/bridge: simple-bridge: Add next panel support

Maxime Ripard
2025-03-04T10:41:47Z

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On Tue, Mar 04, 2025 at 06:15:30PM +0800, Liu Ying wrote:
> The next bridge connected to a simple bridge could be a panel, e.g.,
> a DPI panel connected to a DPI color encoder. Add the next panel support,
> instead of supporting non-panel next bridge only.
>
> Signed-off-by: Liu Ying <victor.liu@nxp.com>
> ---
> drivers/gpu/drm/bridge/Kconfig | 1 +
> drivers/gpu/drm/bridge/simple-bridge.c | 32 ++++++++++++++++----------
> 2 files changed, 21 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index d20f1646dac2..92187dbdd32b 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -310,6 +310,7 @@ config DRM_SIMPLE_BRIDGE
> tristate "Simple DRM bridge support"
> depends on OF
> select DRM_KMS_HELPER
> + select DRM_PANEL_BRIDGE
> help
> Support for non-programmable DRM bridges, such as ADI ADV7123, TI
> THS8134 and THS8135 or passive resistor ladder DACs.
> diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c
> index c0445bd20e07..4c585e5583ca 100644
> --- a/drivers/gpu/drm/bridge/simple-bridge.c
> +++ b/drivers/gpu/drm/bridge/simple-bridge.c
> @@ -19,6 +19,7 @@
> #include <drm/drm_crtc.h>
> #include <drm/drm_edid.h>
> #include <drm/drm_of.h>
> +#include <drm/drm_panel.h>
> #include <drm/drm_print.h>
> #include <drm/drm_probe_helper.h>
>
> @@ -35,6 +36,7 @@ struct simple_bridge {
> const struct simple_bridge_info *info;
>
> struct drm_bridge *next_bridge;
> + struct drm_panel *next_panel;
> struct regulator *vdd;
> struct gpio_desc *enable;
>
> @@ -114,6 +116,10 @@ static int simple_bridge_attach(struct drm_bridge *bridge,
> struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
> int ret;
>
> + if (sbridge->next_panel)
> + return drm_bridge_attach(bridge->encoder, sbridge->next_bridge,
> + bridge, flags);
> +
> ret = drm_bridge_attach(bridge->encoder, sbridge->next_bridge, bridge,
> DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> if (ret < 0)
> @@ -247,7 +253,6 @@ static int simple_bridge_get_dpi_color_coding(struct simple_bridge *sbridge,
> static int simple_bridge_probe(struct platform_device *pdev)
> {
> struct simple_bridge *sbridge;
> - struct device_node *remote;
> int ret;
>
> sbridge = devm_kzalloc(&pdev->dev, sizeof(*sbridge), GFP_KERNEL);
> @@ -257,17 +262,20 @@ static int simple_bridge_probe(struct platform_device *pdev)
> sbridge->info = of_device_get_match_data(&pdev->dev);
>
> /* Get the next bridge in the pipeline. */
> - remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
> - if (!remote)
> - return -EINVAL;
> -
> - sbridge->next_bridge = of_drm_find_bridge(remote);
> - of_node_put(remote);
> -
> - if (!sbridge->next_bridge) {
> - dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
> - return -EPROBE_DEFER;
> - }
> + ret = drm_of_find_panel_or_bridge(pdev->dev.of_node, 1, -1,
> + &sbridge->next_panel,
> + &sbridge->next_bridge);
> + if (ret)
> + return dev_err_probe(&pdev->dev, ret,
> + "Next panel or bridge not found\n");
> +
> + if (sbridge->next_panel)
> + sbridge->next_bridge = devm_drm_panel_bridge_add(&pdev->dev,
> + sbridge->next_panel);
> +
> + if (IS_ERR(sbridge->next_bridge))
> + return dev_err_probe(&pdev->dev, PTR_ERR(sbridge->next_bridge),
> + "Next bridge not found\n");

This makes sense in general, but I think a better approach would be to
use devm/drmm_of_get_bridge here.

Maxime

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