linux-kernel - Re: [PATCH v12 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver

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Date:   Thu, 30 Jun 2022 10:29:27 +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 v12 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort
 driver

Hi, Bo-Chen:

On Mon, 2022-06-27 at 16:03 +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 int mtk_dp_dt_parse(struct mtk_dp *mtk_dp,
> +			   struct platform_device *pdev)
> +{
> +	struct device_node *of_node = pdev->dev.of_node;
> +	struct device *dev = &pdev->dev;
> +	int ret = 0;
> +	void __iomem *base;
> +	u32 linkrate;
> +	int len;
> +
> +	base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	mtk_dp->regs = devm_regmap_init_mmio(dev, base,
> &mtk_dp_regmap_config);
> +	if (IS_ERR(mtk_dp->regs))
> +		return PTR_ERR(mtk_dp->regs);
> +
> +	len = of_property_count_elems_of_size(of_node,
> +					      "data-lanes",
> sizeof(u32));
> +	if (len < 0 || len > 4 || len == 3) {
> +		dev_err(dev, "invalid data lane size: %d\n", len);
> +		return -EINVAL;
> +	}
> +
> +	mtk_dp->max_lanes = len;
> +
> +	ret = device_property_read_u32(dev, "max-linkrate-mhz",
> &linkrate);
> +	if (ret) {
> +		dev_err(dev, "failed to read max linkrate: %d\n", ret);
> +		return ret;
> +	}
> +
> +	switch (linkrate) {
> +	case 8100: /* 8.1G */
> +		mtk_dp->max_linkrate = DP_LINK_BW_8_1;
> +		break;
> +	case 5400: /* 5.4G */
> +		mtk_dp->max_linkrate = DP_LINK_BW_5_4;
> +		break;
> +	case 2700: /* 2.7G */
> +		mtk_dp->max_linkrate = DP_LINK_BW_2_7;
> +		break;
> +	case 1620: /* 1.62G */
> +		mtk_dp->max_linkrate = DP_LINK_BW_1_62;
> +		break;
> +	default:
> +		dev_err(dev, "invalid linkrate: %d\n", linkrate);
> +		return -EINVAL;
> +	}

Use drm_dp_link_rate_to_bw_code() instead of self-implementation.

Regards,
CK

> +
> +	return 0;
> +}
> +