linux-kernel - Re: [PATCH v2 4/6] drm/meson: encoder_hdmi: switch to bridge DRM_BRIDGE_ATTACH_NO

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Date:   Sat, 16 Oct 2021 00:07:04 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     daniel@...ll.ch, Laurent.pinchart@...asonboard.com,
        sam@...nborg.org, dri-devel@...ts.freedesktop.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/6] drm/meson: encoder_hdmi: switch to bridge DRM_BRIDGE_ATTACH_NO_CONNECTOR

Hi Neil,

On Fri, Oct 15, 2021 at 4:11 PM Neil Armstrong <narmstrong@...libre.com> wrote:
>
> This implements the necessary change to no more use the embedded
> connector in dw-hdmi and use the dedicated bridge connector driver
> by passing DRM_BRIDGE_ATTACH_NO_CONNECTOR to the bridge attach call.
>
> The necessary connector properties are added to handle the same
> functionalities as the embedded dw-hdmi connector, i.e. the HDR
> metadata, the CEC notifier & other flags.
>
> The dw-hdmi output_port is set to 1 in order to look for a connector
> next bridge in order to get DRM_BRIDGE_ATTACH_NO_CONNECTOR working.
>
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> Acked-by: Sam Ravnborg <sam@...nborg.org>
another great piece which helps a lot with HDMI support for the 32-bit SoCs!
I have one question below - but regardless of the answer there this gets my:
Acked-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>

[...]
> +       pdev = of_find_device_by_node(remote);
I am wondering if we should use something like:
    encoder_hdmi->cec_notifier_pdev

> +       if (pdev) {
> +               struct cec_connector_info conn_info;
> +               struct cec_notifier *notifier;
> +
> +               cec_fill_conn_info_from_drm(&conn_info, meson_encoder_hdmi->connector);
> +
> +               notifier = cec_notifier_conn_register(&pdev->dev, NULL, &conn_info);
> +               if (!notifier)
> +                       return -ENOMEM;
> +
> +               meson_encoder_hdmi->cec_notifier = notifier;
> +       }
and then move this logic to meson_encoder_hdmi_attach()
This would be important if .detach() and .attach() can be called
multiple times (for example during suspend and resume). But I am not
sure if that's a supported use-case.


Best regards,
Martin