linux-kernel - Re: [PATCH v3 2/3] Subject: [PATCH] drm/mediatek/dp: Add HDCP2.x feature for DisplayPort

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Message-ID: <c72c1114514452450c8248f894bc332ce2778477.camel@mediatek.com>
Date: Fri, 19 Jul 2024 04:05:13 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: Mac Shen (沈俊) <Mac.Shen@...iatek.com>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
	Jitao Shi (石记涛) <jitao.shi@...iatek.com>,
	"daniel@...ll.ch" <daniel@...ll.ch>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>, "airlied@...il.com" <airlied@...il.com>,
	"matthias.bgg@...il.com" <matthias.bgg@...il.com>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>
CC: "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>,
	Shuijing Li (李水静) <Shuijing.Li@...iatek.com>
Subject: Re: [PATCH v3 2/3] Subject: [PATCH] drm/mediatek/dp: Add HDCP2.x
 feature for DisplayPort

Hi, Mac:

On Sat, 2024-06-08 at 20:01 +0800, mac.shen wrote:
> Changes in v3:
> - refine the function to get system time
> - refine the flow to do HDCP with content type and
>   protection value which set by user space
> - refine the flow to update content protection
> - refine the flow to do HDCP2.x authentication
> per suggestion from the previous thread:
> https://urldefense.com/v3/__https://patchwork.kernel.org/project/linux-mediatek__;!!CTRNKA9wMg0ARbw!md6xUiYN88D2YmETs8FQgaExM2zH8S1SmAEU9GRchwpNsXOyDFul3ziVKhRpCJaj8Rcn-gvM-801runjwA$ 
> /patch/20240205055055.25340-3-mac.shen@...iatek.com/
> 
> Signed-off-by: mac.shen <mac.shen@...iatek.com>
> ---

[snip]

> +static int dp_tx_hdcp2x_enable_auth(struct mtk_hdcp_info *hdcp_info, bool enable)
> +{
> +	struct mtk_dp *mtk_dp = container_of(hdcp_info, struct mtk_dp, hdcp_info);
> +	u32 version;
> +	int ret;
> +
> +	dp_tx_hdcp2x_set_auth_pass(hdcp_info, enable);
> +	if (!enable) {
> +		ret = tee_hdcp_enable_encrypt(hdcp_info, enable, HDCP_NONE);
> +		if (ret)
> +			return ret;
> +		mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3000, 0, HDCP_FRAME_EN_DP_ENC0_P0);
> +
> +		return 0;
> +	}
> +
> +	if (HDCP_2_2_HDCP1_DEVICE_CONNECTED(hdcp_info->hdcp2_info.hdcp_rx.recvid_list.rx_info[1]))
> +		version = HDCP_V1;

dp_tx_hdcp2x_enable_auth() is called only when HDCP 2.x, but here detect that version is 1.
I don't know the specification of HDCP, is this is an error case?
Or if this is a normal case, please add some comment here to explain for someone who don't know HDCP specification.

Regards,
CK

> +	else if (HDCP_2_2_HDCP_2_0_REP_CONNECTED
> +		(hdcp_info->hdcp2_info.hdcp_rx.recvid_list.rx_info[1]))
> +		version = HDCP_V2;
> +	else
> +		version = HDCP_V2_3;
> +
> +	ret = tee_hdcp_enable_encrypt(hdcp_info, enable, version);
> +	if (ret)
> +		return ret;
> +	mtk_dp_update_bits(mtk_dp, MTK_DP_ENC0_P0_3000,
> +			   HDCP_FRAME_EN_DP_ENC0_P0, HDCP_FRAME_EN_DP_ENC0_P0);
> +
> +	return 0;
> +}
> +