linux-kernel - Re: [PATCH v3 14/17] drm/mediatek: add OUTPROC support for MT8196

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Message-ID: <778e9796ed50d8f9aaf11b6f1fa1f19386eb71d6.camel@mediatek.com>
Date: Wed, 18 Jun 2025 08:23:38 +0000
From: CK Hu (胡俊光) <ck.hu@...iatek.com>
To: "robh@...nel.org" <robh@...nel.org>, "krzk+dt@...nel.org"
	<krzk+dt@...nel.org>, Paul-pl Chen (陳柏霖)
	<Paul-pl.Chen@...iatek.com>, "conor+dt@...nel.org" <conor+dt@...nel.org>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	"chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>
CC: Sunny Shen (沈姍姍) <Sunny.Shen@...iatek.com>,
	Sirius Wang (王皓昱) <Sirius.Wang@...iatek.com>,
	Nancy Lin (林欣螢) <Nancy.Lin@...iatek.com>,
	Xiandong Wang (王先冬)
	<Xiandong.Wang@...iatek.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "dri-devel@...ts.freedesktop.org"
	<dri-devel@...ts.freedesktop.org>, Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	Jason-JH Lin (林睿祥) <Jason-JH.Lin@...iatek.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"fshao@...omium.org" <fshao@...omium.org>, "p.zabel@...gutronix.de"
	<p.zabel@...gutronix.de>, Singo Chang (張興國)
	<Singo.Chang@...iatek.com>, "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>, "treapking@...omium.org" <treapking@...omium.org>
Subject: Re: [PATCH v3 14/17] drm/mediatek: add OUTPROC support for MT8196

On Thu, 2025-05-15 at 17:34 +0800, paul-pl.chen wrote:
> From: Nancy Lin <nancy.lin@...iatek.com>
> 
> OUTPROC handles the post-stage of pixel processing in
> the overlapping procedure.OUTPROC manages pixels for
> gamma correction and ensures that pixel values are
> within the correct range.
> 
> Signed-off-by: Nancy Lin <nancy.lin@...iatek.com>
> Signed-off-by: Paul-pl Chen <paul-pl.chen@...iatek.com>
> ---

[snip]

> +void mtk_disp_outproc_config(struct device *dev, unsigned int w,
> +			     unsigned int h, unsigned int vrefresh,
> +			     unsigned int bpc, struct cmdq_pkt *cmdq_pkt)
> +{
> +	struct mtk_disp_outproc *priv = dev_get_drvdata(dev);
> +	u32 tmp;
> +
> +	dev_dbg(dev, "%s-w:%d, h:%d\n", __func__, w, h);
> +
> +	writel((h << 16) | w, priv->regs + DISP_REG_OVL_OUTPROC_ROI_SIZE);
> +
> +	tmp = readl(priv->regs + DISP_REG_OVL_OUTPROC_DATAPATH_CON);
> +	tmp = (tmp & ~OVL_OUTPROC_DATAPATH_CON_OUTPUT_CLAMP) |
> +		  (OVL_OUTPROC_DATAPATH_CON_OUTPUT_CLAMP & OVL_OUTPROC_DATAPATH_CON_OUTPUT_CLAMP);

This would simplified as

tmp |= OVL_OUTPROC_DATAPATH_CON_OUTPUT_CLAMP;

> +	writel(tmp, priv->regs + DISP_REG_OVL_OUTPROC_DATAPATH_CON);
> +}
> +
> +void mtk_disp_outproc_start(struct device *dev)
> +{
> +	struct mtk_disp_outproc *priv = dev_get_drvdata(dev);
> +	unsigned int tmp;
> +
> +	tmp = readl(priv->regs + DISP_REG_OVL_OUTPROC_SHADOW_CTRL);
> +	tmp = tmp | OVL_OUTPROC_BYPASS_SHADOW;

tmp |= OVL_OUTPROC_BYPASS_SHADOW;

> +	writel(tmp, priv->regs + DISP_REG_OVL_OUTPROC_SHADOW_CTRL);
> +
> +	writel(0, priv->regs + DISP_REG_OVL_OUTPROC_INTSTA);

To align OVL driver, clear interrupt status in enable_vblank() function.

> +
> +	tmp = readl(priv->regs + DISP_REG_OVL_OUTPROC_EN);
> +	tmp = (tmp & ~OVL_OUTPROC_OVL_EN) | (OVL_OUTPROC_OVL_EN & OVL_OUTPROC_OVL_EN);

This would be simplified as

tmp |= OVL_OUTPROC_OVL_EN;

One question. In mtk_disp_outproc_stop(), you overwrite the whole register of  DISP_REG_OVL_OUTPROC_EN.
Why here not overwrite the whole register?

Regards,
CK

> +	writel(tmp, priv->regs + DISP_REG_OVL_OUTPROC_EN);
> +}
> +
> +void mtk_disp_outproc_stop(struct device *dev)
> +{
> +	struct mtk_disp_outproc *priv = dev_get_drvdata(dev);
> +
> +	writel(0, priv->regs + DISP_REG_OVL_OUTPROC_EN);
> +	writel(OVL_OUTPROC_RST, priv->regs + DISP_REG_OVL_OUTPROC_RST);
> +	writel(0, priv->regs + DISP_REG_OVL_OUTPROC_RST);
> +}
> +