linux-kernel - [PATCH v2] drm/bridge: ps8640: Add software to support aux defer

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Date:   Fri, 30 Sep 2022 12:25:06 +0800
From:   Jason Yen <jason.yen@...adetech.corp-partner.google.com>
To:     LKML <linux-kernel@...r.kernel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org
Cc:     treapking@...gle.com,
        Jason Yen <jason.yen@...adetech.corp-partner.google.com>
Subject: [PATCH v2] drm/bridge: ps8640: Add software to support aux defer

This chip can not handle aux defer if the host directly program
its aux registers to access edid/dpcd. So we need let software
to handle the aux defer situation.

Signed-off-by: Jason Yen <jason.yen@...adetech.corp-partner.google.com>
---

Changes in v2:
- Add aux defer handler
- Remove incorrect statements

 drivers/gpu/drm/bridge/parade-ps8640.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c
index 31e88cb39f8a..76ada237096d 100644
--- a/drivers/gpu/drm/bridge/parade-ps8640.c
+++ b/drivers/gpu/drm/bridge/parade-ps8640.c
@@ -286,7 +286,6 @@ static ssize_t ps8640_aux_transfer_msg(struct drm_dp_aux *aux,
 	}
 
 	switch (data & SWAUX_STATUS_MASK) {
-	/* Ignore the DEFER cases as they are already handled in hardware */
 	case SWAUX_STATUS_NACK:
 	case SWAUX_STATUS_I2C_NACK:
 		/*
@@ -303,6 +302,14 @@ static ssize_t ps8640_aux_transfer_msg(struct drm_dp_aux *aux,
 	case SWAUX_STATUS_ACKM:
 		len = data & SWAUX_M_MASK;
 		break;
+	case SWAUX_STATUS_DEFER:
+	case SWAUX_STATUS_I2C_DEFER:
+		if (is_native_aux)
+			msg->reply |= DP_AUX_NATIVE_REPLY_DEFER;
+		else
+			msg->reply |= DP_AUX_I2C_REPLY_DEFER;
+		len = data & SWAUX_M_MASK;
+		break;
 	case SWAUX_STATUS_INVALID:
 		return -EOPNOTSUPP;
 	case SWAUX_STATUS_TIMEOUT:
-- 
2.34.1