linux-kernel - Re: [PATCH v10 18/21] drm/mediatek: Add mt8195 Embedded DisplayPort driver

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Message-ID: <dda245fbb0dd0d98dff4a332c311db5f588594a2.camel@mediatek.com>
Date:   Thu, 9 Jun 2022 15:18:49 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     CK Hu <ck.hu@...iatek.com>,
        Guillaume Ranquet <granquet@...libre.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Chunfeng Yun (云春峰) 
        <Chunfeng.Yun@...iatek.com>,
        Kishon Vijay Abraham I <kishon@...com>,
        Vinod Koul <vkoul@...nel.org>, Helge Deller <deller@....de>,
        Jitao Shi (石记涛) 
        <jitao.shi@...iatek.com>
CC:     Markus Schneider-Pargmann <msp@...libre.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>,
        "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>
Subject: Re: [PATCH v10 18/21] drm/mediatek: Add mt8195 Embedded DisplayPort
 driver

On Tue, 2022-06-07 at 16:01 +0800, CK Hu wrote:
> Hi, Rex:
> 
> On Mon, 2022-05-23 at 12:47 +0200, Guillaume Ranquet wrote:
> > From: Markus Schneider-Pargmann <msp@...libre.com>
> > 
> > This patch adds a 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
> > Jason-JH.Lin <jason-jh.lin@...iatek.com>.
> > 
> > Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
> > Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
> > ---
> 
> [snip]
> 
> > +
> > +static void mtk_dp_state_handler(struct mtk_dp *mtk_dp)
> > +{
> > +	switch (mtk_dp->state) {
> 
> Does mtk_dp->state has any relation with mtk_dp->train_state. If yes,
> mix mtk_dp->state and mtk_dp->train_state into one state. If no, move
> calling mtk_dp_state_handler() out of mtk_dp_train_handler().
> 
> Regards,
> CK
> 

Hello CK,

OK, I will refine this flow.
About the state machine of traning flow, we can review in v11.

BRs,
Bo-Chen

> > +	case MTK_DP_STATE_INITIAL:
> > +		mtk_dp_video_mute(mtk_dp, true);
> > +		mtk_dp->state = MTK_DP_STATE_IDLE;
> > +		break;
> > +
> > +	case MTK_DP_STATE_IDLE:
> > +		if (mtk_dp->train_state == MTK_DP_TRAIN_STATE_NORMAL)
> > +			mtk_dp->state = MTK_DP_STATE_PREPARE;
> > +		break;
> > +
> > +	case MTK_DP_STATE_PREPARE:
> > +		mtk_dp_video_config(mtk_dp);
> > +		mtk_dp_video_enable(mtk_dp, true);
> > +
> > +		mtk_dp->state = MTK_DP_STATE_NORMAL;
> > +		break;
> > +
> > +	case MTK_DP_STATE_NORMAL:
> > +		if (mtk_dp->train_state != MTK_DP_TRAIN_STATE_NORMAL) {
> > +			mtk_dp_video_mute(mtk_dp, true);
> > +			mtk_dp->state = MTK_DP_STATE_IDLE;
> > +		}
> > +		break;
> > +
> > +	default:
> > +		break;
> > +	}
> > +}
> 
>