Commit 729d3530 authored by Lukasz Luba's avatar Lukasz Luba Committed by Sudeep Holla
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drivers: firmware: scmi: Extend SCMI transport layer by trace events 



The SCMI transport layer communicates via mailboxes and shared memory with
firmware running on a microcontroller. It is platform specific how long it
takes to pass a SCMI message. The most sensitive requests are coming from
CPUFreq subsystem, which might be used by the scheduler.
Thus, there is a need to measure these delays and capture anomalies.
This change introduces trace events wrapped around transfer code.

According to Jim's suggestion a unique transfer_id is to distinguish
similar entries which might have the same message id, protocol id and
sequence. This is a case then there are some timeouts in transfers.

Suggested-by: default avatarJim Quinlan <james.quinlan@broadcom.com>
Signed-off-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
parent 257d0e20

drivers/firmware/arm_scmi/common.h

+2 −0
Original line number Diff line number Diff line
@@ -81,6 +81,7 @@ struct scmi_msg { 
/**

 * struct scmi_xfer - Structure representing a message flow

 *

 * @transfer_id: Unique ID for debug & profiling purpose

 * @hdr: Transmit message header

 * @tx: Transmit message

 * @rx: Receive message, the buffer should be pre-allocated to store
@@ -90,6 +91,7 @@ struct scmi_msg { 
 * @async: pointer to delayed response message received event completion

 */

struct scmi_xfer {

	int transfer_id;

	struct scmi_msg_hdr hdr;

	struct scmi_msg tx;

	struct scmi_msg rx;

drivers/firmware/arm_scmi/driver.c

+18 −0
Original line number Diff line number Diff line
@@ -29,6 +29,9 @@ 


#include "common.h"



#define CREATE_TRACE_POINTS

#include <trace/events/scmi.h>



#define MSG_ID_MASK		GENMASK(7, 0)

#define MSG_XTRACT_ID(hdr)	FIELD_GET(MSG_ID_MASK, (hdr))

#define MSG_TYPE_MASK		GENMASK(9, 8)
@@ -61,6 +64,8 @@ enum scmi_error_codes { 
static LIST_HEAD(scmi_list);

/* Protection for the entire list */

static DEFINE_MUTEX(scmi_list_mutex);

/* Track the unique id for the transfers for debug & profiling purpose */

static atomic_t transfer_last_id;



/**

 * struct scmi_xfers_info - Structure to manage transfer information
@@ -304,6 +309,7 @@ static struct scmi_xfer *scmi_xfer_get(const struct scmi_handle *handle, 
	xfer = &minfo->xfer_block[xfer_id];

	xfer->hdr.seq = xfer_id;

	reinit_completion(&xfer->done);

	xfer->transfer_id = atomic_inc_return(&transfer_last_id);



	return xfer;

}
@@ -374,6 +380,10 @@ static void scmi_rx_callback(struct mbox_client *cl, void *m) 


	scmi_fetch_response(xfer, mem);



	trace_scmi_rx_done(xfer->transfer_id, xfer->hdr.id,

			   xfer->hdr.protocol_id, xfer->hdr.seq,

			   msg_type);



	if (msg_type == MSG_TYPE_DELAYED_RESP)

		complete(xfer->async_done);

	else
@@ -439,6 +449,10 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer) 
	if (unlikely(!cinfo))

		return -EINVAL;



	trace_scmi_xfer_begin(xfer->transfer_id, xfer->hdr.id,

			      xfer->hdr.protocol_id, xfer->hdr.seq,

			      xfer->hdr.poll_completion);



	ret = mbox_send_message(cinfo->chan, xfer);

	if (ret < 0) {

		dev_dbg(dev, "mbox send fail %d\n", ret);
@@ -478,6 +492,10 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer) 
	 */

	mbox_client_txdone(cinfo->chan, ret);



	trace_scmi_xfer_end(xfer->transfer_id, xfer->hdr.id,

			    xfer->hdr.protocol_id, xfer->hdr.seq,

			    xfer->hdr.status);



	return ret;

}