linux-kernel - Re: [PATCH v14 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver

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Date:   Wed, 13 Jul 2022 16:22:15 +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>,
        <liangxu.xu@...iatek.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 v14 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort
 driver

Hi, Bo-Chen:

On Tue, 2022-07-12 at 19:12 +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>
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> ---

[snip]

> +
> +static int mtk_dp_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)
> +{
> +	struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
> +	struct drm_crtc *crtc = conn_state->crtc;
> +	unsigned int input_bus_format;
> +
> +	input_bus_format = bridge_state->input_bus_cfg.format;
> +
> +	dev_dbg(mtk_dp->dev, "input format 0x%04x, output format
> 0x%04x\n",
> +		bridge_state->input_bus_cfg.format,
> +		 bridge_state->output_bus_cfg.format);
> +
> +	if (input_bus_format == MEDIA_BUS_FMT_YUYV8_1X16)
> +		mtk_dp->info.format = DP_PIXELFORMAT_YUV422;
> +	else
> +		mtk_dp->info.format = DP_PIXELFORMAT_RGB;
> +
> +	if (!crtc) {
> +		drm_err(mtk_dp->drm_dev,
> +			"Can't enable bridge as connector state doesn't
> have a crtc\n");
> +		return -EINVAL;
> +	}
> +
> +	mtk_dp_parse_drm_mode_timings(mtk_dp, &crtc_state-
> >adjusted_mode);
> +	if (mtk_dp_parse_capabilities(mtk_dp)) {

mtk_dp_bridge_atomic_enable() would call mtk_dp_parse_capabilities(),
so this is redundant.

Regards,
CK

> +		drm_err(mtk_dp->drm_dev,
> +			"Can't enable bridge as nothing is plugged
> in\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +