linux-kernel - [PATCH] platform: cros_ec: Reduce ligthbar get version command

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Message-Id: <20200815034229.3109182-1-gwendal@chromium.org>
Date:   Fri, 14 Aug 2020 20:42:29 -0700
From:   Gwendal Grignou <gwendal@...omium.org>
To:     ejcaruso@...omium.org, drinkcat@...omium.org,
        enric.balletbo@...labora.com, groeck@...omium.org
Cc:     linux-kernel@...r.kernel.org,
        Gwendal Grignou <gwendal@...omium.org>
Subject: [PATCH] platform: cros_ec: Reduce ligthbar get version command

By default, the lightbar commands are set to the
biggest lightbar command and response. That length is greater than 128
bytes and may not work on all machines.
But all EC are probed for lightbar by sending a get version request.
Set that request size precisely.

BUG=chromium:160662061
TEST=Before the command would be:
cros_ec_cmd: version: 0, command: EC_CMD_LIGHTBAR_CMD, outsize: 194, insize: 128, result: 0
Afer:
cros_ec_cmd: version: 0, command: EC_CMD_LIGHTBAR_CMD, outsize: 1, insize: 8, result: 0

Signed-off-by: Gwendal Grignou <gwendal@...omium.org>
---
 drivers/platform/chrome/cros_ec_lightbar.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/platform/chrome/cros_ec_lightbar.c b/drivers/platform/chrome/cros_ec_lightbar.c
index b59180bff5a3e..ef61298c30bdd 100644
--- a/drivers/platform/chrome/cros_ec_lightbar.c
+++ b/drivers/platform/chrome/cros_ec_lightbar.c
@@ -116,6 +116,8 @@ static int get_lightbar_version(struct cros_ec_dev *ec,
 
 	param = (struct ec_params_lightbar *)msg->data;
 	param->cmd = LIGHTBAR_CMD_VERSION;
+	msg->outsize = sizeof(param->cmd);
+	msg->result = sizeof(resp->version);
 	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
 	if (ret < 0) {
 		ret = 0;
-- 
2.28.0.220.ged08abb693-goog