linux-kernel - Re: [PATCH v11 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver

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Message-ID: <602191e9a61687a8ed05b216d0faad0092b05168.camel@mediatek.com>
Date:   Mon, 20 Jun 2022 11:45:56 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     Bo-Chen Chen <rex-bc.chen@...iatek.com>, <chunkuang.hu@...nel.org>,
        <p.zabel@...gutronix.de>, <daniel@...ll.ch>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <mripard@...nel.org>,
        <tzimmermann@...e.de>, <matthias.bgg@...il.com>, <deller@....de>,
        <airlied@...ux.ie>
CC:     <msp@...libre.com>, <granquet@...libre.com>,
        <jitao.shi@...iatek.com>, <wenst@...omium.org>,
        <angelogioacchino.delregno@...labora.com>,
        <dri-devel@...ts.freedesktop.org>,
        <linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-fbdev@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v11 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort
 driver

Hi, Rex:

On Fri, 2022-06-10 at 18:55 +0800, Bo-Chen Chen wrote:
> From: Markus Schneider-Pargmann <msp@...libre.com>
> 
> This patch adds a embedded displayport driver for the MediaTek mt8195
> SoC.
> 
> It supports the MT8195, the embedded DisplayPort units. It offers
> DisplayPort 1.4 with up to 4 lanes.
> 
> The driver creates a child device for the phy. The child device will
> never exist without the parent being active. As they are sharing a
> register range, the parent passes a regmap pointer to the child so
> that
> both can work with the same register range. The phy driver sets
> device
> data that is read by the parent to get the phy device that can be
> used
> to control the phy properties.
> 
> This driver is based on an initial version by
> Jitao shi <jitao.shi@...iatek.com>
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
> [Bo-Chen: Cleanup the drivers and modify comments from reviewers]
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> ---

[snip]

> +
> +static void mtk_dp_poweroff(struct mtk_dp *mtk_dp)
> +{
> +	mutex_lock(&mtk_dp->dp_lock);
> +
> +	mtk_dp_hwirq_enable(mtk_dp, false);
> +	mtk_dp_power_disable(mtk_dp);
> +	phy_exit(mtk_dp->phy);
> +
> +	mutex_unlock(&mtk_dp->dp_lock);
> +}
> +
> +static int mtk_dp_poweron(struct mtk_dp *mtk_dp)
> +{
> +	int ret = 0;
> +
> +	mutex_lock(&mtk_dp->dp_lock);

The dp_poweron/off is only called by bridge_attach/detach, and I think
drm core would not call attach/detach concurrently, so this mutex is
redundant. Remove it.

Regards,
CK

> +
> +	ret = phy_init(mtk_dp->phy);
> +	if (ret) {
> +		dev_err(mtk_dp->dev, "Failed to initialize phy: %d\n",
> ret);
> +		goto err_phy_init;
> +	}
> +	ret = mtk_dp_phy_configure(mtk_dp, MTK_DP_LINKRATE_RBR, 1);
> +	if (ret) {
> +		dev_err(mtk_dp->dev, "Failed to configure phy: %d\n",
> ret);
> +		goto err_phy_config;
> +	}
> +
> +	mtk_dp_init_port(mtk_dp);
> +	mtk_dp_power_enable(mtk_dp);
> +
> +err_phy_config:
> +	phy_exit(mtk_dp->phy);
> +err_phy_init:
> +	mutex_unlock(&mtk_dp->dp_lock);
> +	return ret;
> +}