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

[Rex-BC Chen]

On Tue, 2022-06-07 at 14:21 +0800, CK Hu wrote:
> Hi, Rex:
> 
> On Mon, 2022-05-23 at 12:47 +0200, Guillaume Ranquet wrote:
> > From: Markus Schneider-Pargmann <msp@xxxxxxxxxxxx>
> > 
> > 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@xxxxxxxxxxxx>.
> > 
> > Signed-off-by: Markus Schneider-Pargmann <msp@xxxxxxxxxxxx>
> > Signed-off-by: Guillaume Ranquet <granquet@xxxxxxxxxxxx>
> > ---
> 
> [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)
> 
> event is always > 0, isn't it?
> 
Hello CK,

ok, I will move this to dp patch.

> > +		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);
> 
> I think this ISR would come once. If bridge has not attached, the drm
> core would lost this event. Maybe you should enable eDP hardware
> after
> bridge attached or send this event when attached.
> 

for edp patch, I will move it to (mtk_dp_bridge_attach).
for dp patch, I will add it back.

> > +	}
> > +
> > +	if (mtk_dp->train_info.cable_state_change) {
> 
> Executing this thread imply cable_state_change = true, so drop
> cable_state_change.
> 

In mtk_dp_hpd_isr_handler(), there is another irq
"MTK_DP_HPD_INTERRUPT" which means the sink devices give a interrupt to
source device. it's not about connected status, so I think we still
need this.

> > +		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)) {
> 
> I do not like two variable to present one thing. If
> 
> mtk_dp->train_info.cable_plugged_in = false
> and
> mtk_dp_plug_state(mtk_dp) = ture
> 
> What does this mean? I think this mean 'now' is connected because
> cable_plugged_in is old information and mtk_dp_plug_state() is
> current
> information.
> 
> But I would like to keep cable_plugged_in and drop
> mtk_dp_plug_state()
> because cable_plugged_in would be changed in isr and it would be the
> same as mtk_dp_plug_state().
> 
> Regards,
> CK
> 

ok, I will drop this.

BRs,
Rex

> > +			mtk_dp_video_mute(mtk_dp, true);
> > +
> > +			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;
> > +}
> > +
> 
>