[PATCH 1/1] rivers: scmi: Add completion timeout handling for raw mode transfers

[Artem Shimko]

Fix race conditions in SCMI raw mode implementation by adding proper
completion timeout handling. Multiple tests in the SCMI test suite
were failing due to early clearing of SCMI_XFER_FLAG_IS_RAW flag in
scmi_xfer_raw_put() function.

The root cause:
Tests were failing on poll() system calls with this condition:
    if (!raw || (idx == SCMI_RAW_REPLY_QUEUE && !SCMI_XFER_IS_RAW(xfer)))
        return;

The SCMI_XFER_FLAG_IS_RAW flag was being cleared prematurely before
the transfer completion was properly acknowledged, causing the poll
to return on timeout and tests to fail.

Сhanges implemented:
1. Add completion wait with timeout in  scmi_xfer_raw_worker()
2. Signal completion in scmi_raw_message_report()

This ensures:
- Proper synchronization between transfer completion and flag clearing
- Prevention of indefinite blocking with timeout safety mechanism
- Stable test execution by maintaining correct flag states

arm scmi tests: https://gitlab.arm.com/tests/scmi-tests/-/releases

Signed-off-by: Artem Shimko <a.shimko.dev at gmail.com>
---
 drivers/firmware/arm_scmi/raw_mode.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/firmware/arm_scmi/raw_mode.c b/drivers/firmware/arm_scmi/raw_mode.c
index 73db5492ab44..fb83beb42e7b 100644
--- a/drivers/firmware/arm_scmi/raw_mode.c
+++ b/drivers/firmware/arm_scmi/raw_mode.c
@@ -468,6 +468,12 @@ static void scmi_xfer_raw_worker(struct work_struct *work)
 
 		ret = scmi_xfer_raw_wait_for_message_response(cinfo, xfer,
 							      timeout_ms);
+		if (!ret)
+			if (!wait_for_completion_timeout(&xfer->done, timeout_ms))
+				dev_err(dev,
+					"timed out in RAW resp - HDR:%08X\n",
+					pack_scmi_header(&xfer->hdr));
+
 		if (!ret && xfer->hdr.status)
 			ret = scmi_to_linux_errno(xfer->hdr.status);
 
@@ -1381,6 +1387,8 @@ void scmi_raw_message_report(void *r, struct scmi_xfer *xfer,
 	if (!raw || (idx == SCMI_RAW_REPLY_QUEUE && !SCMI_XFER_IS_RAW(xfer)))
 		return;
 
+	complete(&xfer->done);
+
 	dev = raw->handle->dev;
 	q = scmi_raw_queue_select(raw, idx,
 				  SCMI_XFER_IS_CHAN_SET(xfer) ? chan_id : 0);
-- 
2.43.0