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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Gwendal Grignou <gwendal@chromium.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.9 561/757] platform/chrome: cros_ec_lightbar: Reduce ligthbar get version command
Date:   Tue, 27 Oct 2020 14:53:31 +0100
Message-Id: <20201027135516.815959536@linuxfoundation.org>
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From: Gwendal Grignou <gwendal@chromium.org>

[ Upstream commit 1e7913ff5f9f1b73146ad8522958bd266f22a510 ]

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.

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

Fixes: a841178445bb7 ("mfd: cros_ec: Use a zero-length array for command data")
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Sasha Levin <sashal@kernel.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;
-- 
2.25.1