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Message-ID: <123bc9f79f60de14aad6f46e1c2268cf6f1c27a5.1722945487.git.christophe.jaillet@wanadoo.fr>
Date: Tue, 6 Aug 2024 13:59:11 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>
Cc: linux-kernel@...r.kernel.org,
kernel-janitors@...r.kernel.org,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
dri-devel@...ts.freedesktop.org
Subject: [PATCH 2/2] drm/dp_mst: Slightly optimize drm_dp_mst_i2c_write() (2/2)
'msg' is only used with drm_dp_encode_sideband_req() which takes a
"const struct drm_dp_sideband_msg_req_body *".
So some initializations can be done only once outside of the for loop.
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
In case of interest, on x86_64, with allmodconfig, sizeof(*msg) is 420
bytes.
---
drivers/gpu/drm/display/drm_dp_mst_topology.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 7bf6157eb3a3..a149ff3f70ad 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -5891,10 +5891,16 @@ static int drm_dp_mst_i2c_write(struct drm_dp_mst_branch *mstb,
ret = -ENOMEM;
goto out;
}
+
+ /*
+ * 'msg' is not modified by drm_dp_encode_sideband_req(). So
+ * some initializations can be done only once.
+ */
+ memset(&msg, 0, sizeof(msg));
+ msg.req_type = DP_REMOTE_I2C_WRITE;
+ msg.u.i2c_write.port_number = port->port_num;
+
for (i = 0; i < num; i++) {
- memset(&msg, 0, sizeof(msg));
- msg.req_type = DP_REMOTE_I2C_WRITE;
- msg.u.i2c_write.port_number = port->port_num;
msg.u.i2c_write.write_i2c_device_id = msgs[i].addr;
msg.u.i2c_write.num_bytes = msgs[i].len;
msg.u.i2c_write.bytes = msgs[i].buf;
--
2.45.2
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