Re: [PATCH v2 2/3] drm/bridge: simple-bridge: Support data-enable-active endpoint property

[Frank Li]

On Mon, Oct 19, 2026 at 07:17:15AM -0300, Leonardo Costa wrote:
> From: Leonardo Costa <leonardo.costa@xxxxxxxxxxx>
>
> Some simple bridges, such as a resistor ladder DAC, may include a
> data-enable input that must be driven at a specific polarity.
>
> Read the data-enable-active property from the input endpoint and fill
> the bridge's input bus flags accordingly, so the upstream encoder drives
> DE with the required polarity. The property is applied only if the
> bridge doesn't provide its own timings struct.
>
> Signed-off-by: Leonardo Costa <leonardo.costa@xxxxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/gpu/drm/bridge/simple-bridge.c | 21 ++++++++++++++++++++-
>  1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/simple-bridge.c b/drivers/gpu/drm/bridge/simple-bridge.c
> index 848c2df2a276..c5301295658a 100644
> --- a/drivers/gpu/drm/bridge/simple-bridge.c
> +++ b/drivers/gpu/drm/bridge/simple-bridge.c
> @@ -183,6 +183,9 @@ static int simple_bridge_probe(struct platform_device *pdev)
>  {
>  	struct simple_bridge *sbridge;
>  	struct device_node *remote;
> +	struct device_node *ep;
> +	bool de_present;
> +	u32 de;
>
>  	sbridge = devm_drm_bridge_alloc(&pdev->dev, struct simple_bridge,
>  					bridge, &simple_bridge_bridge_funcs);
> @@ -220,10 +223,26 @@ static int simple_bridge_probe(struct platform_device *pdev)
>  		return dev_err_probe(&pdev->dev, PTR_ERR(sbridge->enable),
>  				     "Unable to retrieve enable GPIO\n");
>
> -	/* Register the bridge. */
>  	sbridge->bridge.of_node = pdev->dev.of_node;
>  	sbridge->bridge.timings = sbridge->info->timings;
>
> +	ep = of_graph_get_endpoint_by_regs(pdev->dev.of_node, 0, -1);
> +	de_present = !of_property_read_u32(ep, "data-enable-active", &de);
> +	of_node_put(ep);
> +
> +	if (de_present && !sbridge->bridge.timings) {
> +		struct drm_bridge_timings *timings;
> +
> +		timings = devm_kzalloc(&pdev->dev, sizeof(*timings), GFP_KERNEL);
> +		if (!timings)
> +			return -ENOMEM;
> +
> +		timings->input_bus_flags = de ? DRM_BUS_FLAG_DE_HIGH :
> +						DRM_BUS_FLAG_DE_LOW;
> +		sbridge->bridge.timings = timings;
> +	}
> +
> +	/* Register the bridge. */
>  	return devm_drm_bridge_add(&pdev->dev, &sbridge->bridge);
>  }
>
>
> --
> 2.43.0
>
>