linux-kernel - Re: [PATCH v2 15/15] drm/mediatek: Introduce HDMI/DDC v2 for MT8195/MT8188

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Message-ID: <803bc2bd802506635dfa9ea9b26a6ca40a7f4912.camel@mediatek.com>
Date: Mon, 16 Dec 2024 08:57:24 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
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Subject: Re: [PATCH v2 15/15] drm/mediatek: Introduce HDMI/DDC v2 for
 MT8195/MT8188

Hi, Angelo:

On Thu, 2024-12-05 at 12:45 +0100, AngeloGioacchino Del Regno wrote:
> External email : Please do not click links or open attachments until you have verified the sender or the content.
> 
> 
> Add support for the newer HDMI-TX (Encoder) v2 and DDC v2 IPs
> found in MediaTek's MT8195, MT8188 SoC and their variants, and
> including support for display modes up to 4k60 and for HDMI
> Audio, as per the HDMI 2.0 spec.
> 
> HDCP and CEC functionalities are also supported by this hardware,
> but are not included in this commit and that also poses a slight
> difference between the V2 and V1 controllers in how they handle
> Hotplug Detection (HPD).
> 
> While the v1 controller was using the CEC controller to check
> HDMI cable connection and disconnection, in this driver the v2
> one does not.
> 
> This is due to the fact that on parts with v2 designs, like the
> MT8195 SoC, there is one CEC controller shared between the HDMI
> Transmitter (HDMI-TX) and Receiver (HDMI-RX): before eventually
> adding support to use the CEC HW to wake up the HDMI controllers
> it is necessary to have support for one TX, one RX *and* for both
> at the same time.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---

[snip]

> +static int mtk_hdmi_v2_bridge_atomic_check(struct drm_bridge *bridge,
> +                                          struct drm_bridge_state *bridge_state,
> +                                          struct drm_crtc_state *crtc_state,
> +                                          struct drm_connector_state *conn_state)
> +{

I would like v1 and v2 has the same behavior.
Why v2 has atomic check but v1 has no?
If this is better to have, add atomic check to v1, and this function would be common function.

Regards,
CK

> +       return drm_atomic_helper_connector_hdmi_check(conn_state->connector,
> +                                                     conn_state->state);
> +}
> +