This is a note to let you know that I've just added the patch titled
firmware: arm_scmi: Remove clear channel call on the TX channel
to the 5.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
firmware-arm_scmi-remove-clear-channel-call-on-the-t.patch
and it can be found in the queue-5.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cc97174874009b0dec1f068a6df162ac4d34ee52
Author: Cristian Marussi <cristian.marussi@xxxxxxx>
Date: Thu Feb 24 15:24:04 2022 +0000
firmware: arm_scmi: Remove clear channel call on the TX channel
[ Upstream commit 98f0d68f94ea21541e0050cc64fa108ade779839 ]
On SCMI transports whose channels are based on a shared resource the TX
channel area has to be acquired by the agent before placing the desired
command into the channel and it will be then relinquished by the platform
once the related reply has been made available into the channel.
On an RX channel the logic is reversed with the platform acquiring the
channel area and the agent reliquishing it once done by calling the
scmi_clear_channel() helper.
As a consequence, even in case of error, the agent must never try to clear
a TX channel from its side: restrict the existing clear channel call on the
the reply path only to delayed responses since they are indeed coming from
the RX channel.
Link: https://lore.kernel.org/r/20220224152404.12877-1-cristian.marussi@xxxxxxx
Fixes: e9b21c96181c ("firmware: arm_scmi: Make .clear_channel optional")
Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index d76bab3aaac4..e815b8f98739 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -652,7 +652,8 @@ static void scmi_handle_response(struct scmi_chan_info *cinfo,
xfer = scmi_xfer_command_acquire(cinfo, msg_hdr);
if (IS_ERR(xfer)) {
- scmi_clear_channel(info, cinfo);
+ if (MSG_XTRACT_TYPE(msg_hdr) == MSG_TYPE_DELAYED_RESP)
+ scmi_clear_channel(info, cinfo);
return;
}
