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

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Message-ID: <088b8e5aa04c24059301a3f14a1214aa3a8865df.camel@mediatek.com>
Date: Fri, 23 Aug 2024 07:30:36 +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_read_ake_send_hprime(struct mtk_hdcp_info *hdcp_info)
> +{
> +	struct mtk_dp *mtk_dp = container_of(hdcp_info, struct mtk_dp, hdcp_info);
> +	ktime_t msg_end;
> +	bool msg_expired;
> +	u8 rx_status = 0;
> +	int timeout;
> +	ssize_t ret;
> +
> +	dev_dbg(mtk_dp->dev, "[HDCP2.X] HDCP_2_2_AKE_SEND_HPRIME\n");
> +
> +	timeout = hdcp_info->hdcp2_info.stored_km ?
> +		HDCP_2_2_HPRIME_PAIRED_TIMEOUT_MS : HDCP_2_2_HPRIME_NO_PAIRED_TIMEOUT_MS;
> +
> +	dp_tx_hdcp2x_wait_for_cp_irq(hdcp_info, timeout);
> +	hdcp_info->hdcp2_info.cp_irq_cached = atomic_read(&hdcp_info->hdcp2_info.cp_irq);

cp_irq_cached is updated always after dp_tx_hdcp2x_wait_for_cp_irq(),
and  cp_irq_cached is only used in dp_tx_hdcp2x_wait_for_cp_irq(),
so move this update into dp_tx_hdcp2x_wait_for_cp_irq().

Regards,
CK

> +
> +	ret = drm_dp_dpcd_read(&mtk_dp->aux, DP_HDCP_2_2_REG_RXSTATUS_OFFSET, &rx_status,
> +			       HDCP_2_2_DP_RXSTATUS_LEN);
> +	if (ret != HDCP_2_2_DP_RXSTATUS_LEN)
> +		return ret >= 0 ? -EIO : ret;
> +
> +	if (!HDCP_2_2_DP_RXSTATUS_H_PRIME(rx_status))
> +		return -EAGAIN;
> +
> +	msg_end = ktime_add_ms(ktime_get_raw(), HDCP_2_2_DP_HPRIME_READ_TIMEOUT_MS);
> +
> +	ret = drm_dp_dpcd_read(&mtk_dp->aux, DP_HDCP_2_2_AKE_SEND_HPRIME_OFFSET,
> +			       hdcp_info->hdcp2_info.hdcp_rx.send_hprime.h_prime,
> +		HDCP_2_2_H_PRIME_LEN);
> +	if (ret < 0)
> +		return ret;
> +
> +	msg_expired = ktime_after(ktime_get_raw(), msg_end);
> +	if (msg_expired)
> +		dev_dbg(mtk_dp->dev, "[HDCP2.X] Timeout to read AKE hprime\n");
> +
> +	return 0;
> +}
> +