Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Paul Cercueil <paul@crapouillou.net>
To:     Phong LE <ple@baylibre.com>,
        Neil Armstrong <neil.armstrong@linaro.org>,
        Andrzej Hajda <andrzej.hajda@intel.com>,
        Robert Foss <robert.foss@linaro.org>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Jonas Karlman <jonas@kwiboo.se>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>
Cc:     list@opendingux.net, dri-devel@lists.freedesktop.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Paul Cercueil <paul@crapouillou.net>
Subject: [PATCH 08/10] drm: bridge: it66121: Set DDC preamble only once before reading EDID
Date:   Wed, 14 Dec 2022 13:58:19 +0100
Message-Id: <20221214125821.12489-9-paul@crapouillou.net>
In-Reply-To: <20221214125821.12489-1-paul@crapouillou.net>
References: <20221214125821.12489-1-paul@crapouillou.net>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The DDC preamble and target address only need to be set once before
reading the EDID, even if multiple segments have to be read.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
 drivers/gpu/drm/bridge/ite-it66121.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it66121.c b/drivers/gpu/drm/bridge/ite-it66121.c
index 5335d4abd7c5..7972003d4776 100644
--- a/drivers/gpu/drm/bridge/ite-it66121.c
+++ b/drivers/gpu/drm/bridge/ite-it66121.c
@@ -506,9 +506,6 @@ static int it66121_get_edid_block(void *context, u8 *buf,
 	while (remain > 0) {
 		cnt = (remain > IT66121_EDID_FIFO_SIZE) ?
 				IT66121_EDID_FIFO_SIZE : remain;
-		ret = it66121_preamble_ddc(ctx);
-		if (ret)
-			return ret;
 
 		ret = regmap_write(ctx->regmap, IT66121_DDC_COMMAND_REG,
 				   IT66121_DDC_COMMAND_FIFO_CLR);
@@ -519,15 +516,6 @@ static int it66121_get_edid_block(void *context, u8 *buf,
 		if (ret)
 			return ret;
 
-		ret = it66121_preamble_ddc(ctx);
-		if (ret)
-			return ret;
-
-		ret = regmap_write(ctx->regmap, IT66121_DDC_HEADER_REG,
-				   IT66121_DDC_HEADER_EDID);
-		if (ret)
-			return ret;
-
 		ret = regmap_write(ctx->regmap, IT66121_DDC_OFFSET_REG, offset);
 		if (ret)
 			return ret;
@@ -842,9 +830,25 @@ static struct edid *it66121_bridge_get_edid(struct drm_bridge *bridge,
 {
 	struct it66121_ctx *ctx = container_of(bridge, struct it66121_ctx, bridge);
 	struct edid *edid;
+	int ret;
 
 	mutex_lock(&ctx->lock);
+	ret = it66121_preamble_ddc(ctx);
+	if (ret) {
+		edid = ERR_PTR(ret);
+		goto out_unlock;
+	}
+
+	ret = regmap_write(ctx->regmap, IT66121_DDC_HEADER_REG,
+			   IT66121_DDC_HEADER_EDID);
+	if (ret) {
+		edid = ERR_PTR(ret);
+		goto out_unlock;
+	}
+
 	edid = drm_do_get_edid(connector, it66121_get_edid_block, ctx);
+
+out_unlock:
 	mutex_unlock(&ctx->lock);
 
 	return edid;
-- 
2.35.1