linux-kernel - [PATCH v6 02/10] drm/bridge: it6505: improve AUX operation for edid read

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Message-Id: <20241016-upstream-v6-v6-2-4d93a0c46de1@ite.com.tw>
Date: Wed, 16 Oct 2024 15:54:14 +0800
From: Hermes Wu via B4 Relay <devnull+Hermes.wu.ite.com.tw@...nel.org>
To: Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Pin-yen Lin <treapking@...omium.org>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Kenneth Hung <Kenneth.hung@....com.tw>, Pet Weng <Pet.Weng@....com.tw>, 
 Hermes Wu <Hermes.wu@....com.tw>
Subject: [PATCH v6 02/10] drm/bridge: it6505: improve AUX operation for
 edid read

From: Hermes Wu <Hermes.wu@....com.tw>

The original AUX operation using data registers is limited to 4 bytes.
The AUX operation command CMD_AUX_I2C_EDID_READ uses AUX FIFO and
is capable of reading 16 bytes.
This improves the speed of EDID read.

Signed-off-by: Hermes Wu <Hermes.wu@....com.tw>
---
 drivers/gpu/drm/bridge/ite-it6505.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index 3272ca6951f2585f9592834869de23ac50ce41a4..9747d7ccf435d536da55c6a3ff79e504b7c724f0 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -1076,10 +1076,13 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
 				      size_t size, enum aux_cmd_reply *reply)
 {
 	int i, ret_size, ret = 0, request_size;
+	int fifo_max_size = (cmd == CMD_AUX_I2C_EDID_READ) ? AUX_FIFO_MAX_SIZE : 4;
 
 	mutex_lock(&it6505->aux_lock);
-	for (i = 0; i < size; i += 4) {
-		request_size = min((int)size - i, 4);
+	i = 0;
+	do {
+		request_size = min_t(int, (int)size - i, fifo_max_size);
+
 		ret_size = it6505_aux_operation(it6505, cmd, address + i,
 						buffer + i, request_size,
 						reply);
@@ -1088,8 +1091,9 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
 			goto aux_op_err;
 		}
 
+		i += request_size;
 		ret += ret_size;
-	}
+	} while (i < size);
 
 aux_op_err:
 	mutex_unlock(&it6505->aux_lock);

-- 
2.34.1