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

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Date:   Thu, 9 Jun 2022 16:00:21 +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 17:04 +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 irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
> > +{
> > +	struct mtk_dp *mtk_dp = dev;
> > +	int event;
> > +	u8 buf[DP_RECEIVER_CAP_SIZE] = {};
> > +
> > +	event = mtk_dp_plug_state(mtk_dp) ? connector_status_connected
> > :
> > +						  connector_status_disc
> > onnected;
> > +
> > +	if (event < 0)
> > +		return IRQ_HANDLED;
> > +
> > +	if (mtk_dp->drm_dev) {
> > +		dev_info(mtk_dp->dev, "drm_helper_hpd_irq_event\n");
> > +		drm_helper_hpd_irq_event(mtk_dp->bridge.dev);
> > +	}
> > +
> > +	if (mtk_dp->train_info.cable_state_change) {
> > +		mtk_dp->train_info.cable_state_change = false;
> > +
> > +		mtk_dp->train_state = MTK_DP_TRAIN_STATE_STARTUP;
> > +
> > +		if (!mtk_dp->train_info.cable_plugged_in ||
> > +		    !mtk_dp_plug_state(mtk_dp)) {
> > +			mtk_dp_video_mute(mtk_dp, true);
> 
> For eDP, when does 'unplug' happen? Explain this or move unplug
> processing to DP patch.
> 
> Regards,
> CK
> 

Hello CK,

ok, I move them to dp patch.

BRs,
Bo-Chen

> > +
> > +			mtk_dp_initialize_priv_data(mtk_dp);
> > +			mtk_dp_set_idle_pattern(mtk_dp, true);
> > +			if (mtk_dp->has_fec)
> > +				mtk_dp_fec_enable(mtk_dp, false);
> > +
> > +			mtk_dp_update_bits(mtk_dp,
> > MTK_DP_TOP_PWR_STATE,
> > +					   DP_PWR_STATE_BANDGAP_TPLL,
> > +					   DP_PWR_STATE_MASK);
> > +		} else {
> > +			mtk_dp_update_bits(mtk_dp,
> > MTK_DP_TOP_PWR_STATE,
> > +					   DP_PWR_STATE_BANDGAP_TPLL_LA
> > NE,
> > +					   DP_PWR_STATE_MASK);
> > +			drm_dp_read_dpcd_caps(&mtk_dp->aux, buf);
> > +			mtk_dp->train_info.link_rate =
> > +				min_t(int, mtk_dp->max_linkrate,
> > +				      buf[mtk_dp->max_linkrate]);
> > +			mtk_dp->train_info.lane_count =
> > +				min_t(int, mtk_dp->max_lanes,
> > +				      drm_dp_max_lane_count(buf));
> > +		}
> > +	}
> > +
> > +	if (mtk_dp->train_info.irq_status & MTK_DP_HPD_INTERRUPT) {
> > +		dev_dbg(mtk_dp->dev, "MTK_DP_HPD_INTERRUPT\n");
> > +		mtk_dp->train_info.irq_status &= ~MTK_DP_HPD_INTERRUPT;
> > +		mtk_dp_hpd_sink_event(mtk_dp);
> > +	}
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> 
>