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From:   Prashant Malani <pmalani@chromium.org>
To:     linux-kernel@vger.kernel.org, chrome-platform@lists.linux.dev
Cc:     bleung@chromium.org, Prashant Malani <pmalani@chromium.org>
Subject: [PATCH] platform/chrome: cros_typec_vdm: Fix VDO copy
Date:   Fri, 13 Jan 2023 18:26:26 +0000
Message-Id: <20230113182626.1149539-1-pmalani@chromium.org>
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The usage of memcpy() affects the representation of the VDOs as they are
copied to the EC Host Command buffer. Specifically, all higher order
bits get dropped (for example: a VDO of 0x406 just gets copied as 0x6).

Avoid this by explicitly copying each VDO in the array. The number of
VDOs generated by alternate mode drivers in their VDMs is almost always
just 1 (apart from the header) so this doesn't affect performance in a
meaningful way).

Fixes: 40a9b13a09ef ("platform/chrome: cros_typec_vdm: Add VDM send support")
Signed-off-by: Prashant Malani <pmalani@chromium.org>
---
 drivers/platform/chrome/cros_typec_vdm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/chrome/cros_typec_vdm.c b/drivers/platform/chrome/cros_typec_vdm.c
index aca9d337118e..06f4a55999c5 100644
--- a/drivers/platform/chrome/cros_typec_vdm.c
+++ b/drivers/platform/chrome/cros_typec_vdm.c
@@ -86,10 +86,12 @@ static int cros_typec_port_amode_vdm(struct typec_altmode *amode, const u32 hdr,
 		.command = TYPEC_CONTROL_COMMAND_SEND_VDM_REQ,
 	};
 	struct typec_vdm_req vdm_req = {};
+	int i;
 
 	vdm_req.vdm_data[0] = hdr;
 	vdm_req.vdm_data_objects = cnt;
-	memcpy(&vdm_req.vdm_data[1], vdo, cnt - 1);
+	for (i = 1; i < cnt; i++)
+		vdm_req.vdm_data[i] = vdo[i-1];
 	vdm_req.partner_type = TYPEC_PARTNER_SOP;
 	req.vdm_req_params = vdm_req;
 
-- 
2.39.0.314.g84b9a713c41-goog