[PATCH v15 05/11] drm/mediatek: Add MT8195 Embedded DisplayPort driver

[CK Hu]

Hi, Bo-Chen:

On Wed, 2022-07-27 at 12:50 +0800, Bo-Chen Chen wrote:
> From: Markus Schneider-Pargmann <msp at baylibre.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 at mediatek.com>
> 
> Signed-off-by: Markus Schneider-Pargmann <msp at baylibre.com>
> Signed-off-by: Guillaume Ranquet <granquet at baylibre.com>
> Signed-off-by: Bo-Chen Chen <rex-bc.chen at mediatek.com>
> ---

[snip]

> +
> +static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
> +{
> +	struct mtk_dp *mtk_dp = dev;
> +
> +	if (mtk_dp->train_info.hpd_inerrupt) {

When the thread is running, mtk_dp->train_info.hpd_inerrupt would be
true. So this checking is redundant.

> +		dev_dbg(mtk_dp->dev, "MTK_DP_HPD_INTERRUPT\n");
> +		mtk_dp->train_info.hpd_inerrupt = false;
> +		mtk_dp_hpd_sink_event(mtk_dp);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t mtk_dp_hpd_event(int hpd, void *dev)
> +{
> +	struct mtk_dp *mtk_dp = dev;
> +	struct mtk_dp_train_info *train_info = &mtk_dp->train_info;
> +	u32 irq_status;
> +
> +	irq_status = mtk_dp_read(mtk_dp, MTK_DP_TOP_IRQ_STATUS);
> +
> +	if (!irq_status)
> +		return IRQ_HANDLED;
> +
> +	if (irq_status & RGS_IRQ_STATUS_TRANSMITTER) {

Combine this if-checking with previous if-checking, it would be:

if (!(irq_status & RGS_IRQ_STATUS_TRANSMITTER))
	return IRQ_HANDLED;

> +		irq_status = mtk_dp_swirq_get_clear(mtk_dp) |
> +			     mtk_dp_hwirq_get_clear(mtk_dp);
> +
> +		if (!irq_status)
> +			return IRQ_HANDLED;
> +
> +		if (irq_status & MTK_DP_HPD_INTERRUPT)

Does this interrupt MTK_DP_HPD_INTERRUPT have any relation with
MTK_DP_HPD_CONNECT and MTK_DP_HPD_CONNECT? From the naming, I guess
that when MTK_DP_HPD_CONNECT happen, MTK_DP_HPD_INTERRUPT would also
happen. Either for MTK_DP_HPD_DISCONNECT. When would
MTK_DP_HPD_INTERRUPT happen but MTK_DP_HPD_CONNECT or
MTK_DP_HPD_DISCONNECT does not happen.

Regards,
CK

> +			train_info->hpd_inerrupt = true;
> +
> +		if (!(irq_status & MTK_DP_HPD_CONNECT ||
> +		      irq_status & MTK_DP_HPD_DISCONNECT))
> +			return IRQ_WAKE_THREAD;
> +
> +		if (!!(mtk_dp_read(mtk_dp, MTK_DP_TRANS_P0_3414) &
> +		       HPD_DB_DP_TRANS_P0_MASK))
> +			train_info->cable_plugged_in = true;
> +		else
> +			train_info->cable_plugged_in = false;
> +
> +		mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
> +				   DP_PWR_STATE_BANDGAP_TPLL_LANE,
> +				   DP_PWR_STATE_MASK);
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +