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Author: Nikolai-L

docs/hw-reset-followup-plan.md

@@ -17,7 +17,7 @@ The `reset_issue_dmesg.txt` log shows 35 consecutive userspace-triggered HW rese
 
 ### Steps
 
-1. **Add tracking fields to `struct ds5`** (`kernel/realsense/d4xx.c`):
+1. **Add tracking fields to `struct ds5_dev`** (`kernel/realsense/d4xx.c`):
    - `int consecutive_reset_failures` — incremented when `ds5_hw_reset_with_recovery()` returns an error, reset to 0 on success
    - `unsigned long last_reset_jiffies` — timestamp of the last reset attempt
    - `int total_resets` — lifetime counter for diagnostics (never reset)
@@ -57,7 +57,7 @@ The `reset_issue_dmesg.txt` log shows 35 consecutive userspace-triggered HW rese
 
 ## Design Decisions
 
-- **Circuit-breaker is per-instance, not per-camera**: Each `struct ds5` has its own counter. Since userspace sends HW reset to one instance (typically Depth at `9-001a`), this naturally tracks per-camera. Peer instances aren't reset independently.
+- **Circuit-breaker is per-camera, shared across instances**: The tracking fields live in `struct ds5_dev`, so all `struct ds5` instances for the same physical camera share a single counter and breaker state. If any instance (typically Depth at `9-001a`) trips the breaker, further HW reset requests from any instance for that camera are rejected until the breaker auto‑clears.
 - **Return -EBUSY for tripped breaker, -EAGAIN for cooldown**: Distinct error codes let userspace distinguish "permanently failed" from "try again later".
 - **Auto-clear after 60s inactivity**: Avoids permanent lockout. If the camera recovers externally (e.g., power cycle), the driver will accept resets again.
 - **Phase 1 dual-camera is diagnostic only**: No blocking behavior added — just logging. If field data shows disruption, we can add a sibling-streaming gate in a future commit.

kernel/realsense/d4xx.c

@@ -2431,21 +2431,21 @@ static int ds5_hw_reset_serdes_recovery(struct ds5 *state, bool force_phase2)
 		 * later.  Do multiple reads with delays to catch oscillation.
 		 */
 		ret = ds5_read(state, DS5_FW_VERSION, &tmp);
-        if (ret == 0) {
-            int k;
-            bool stable = true;
-
-            for (k = 0; k < DS5_HW_RESET_STABILITY_READS; k++) {
-                msleep(DS5_HW_RESET_STABILITY_INTERVAL_MS);
-                ret = ds5_read(state, DS5_FW_VERSION, &tmp);
-                if (ret < 0) {
-                    dev_warn(&state->client->dev,
-                        "%s(): Phase 1 stability check %d/%d failed (err %d)\n",
-                        __func__, k + 1, DS5_HW_RESET_STABILITY_READS, ret);
-                    stable = false;
-                    break;
-                }
-            }
+		if (ret == 0) {
+			int k;
+			bool stable = true;
+
+			for (k = 0; k < DS5_HW_RESET_STABILITY_READS; k++) {
+				msleep(DS5_HW_RESET_STABILITY_INTERVAL_MS);
+				ret = ds5_read(state, DS5_FW_VERSION, &tmp);
+				if (ret < 0) {
+					dev_warn(&state->client->dev,
+						"%s(): Phase 1 stability check %d/%d failed (err %d)\n",
+						__func__, k + 1, DS5_HW_RESET_STABILITY_READS, ret);
+					stable = false;
+					break;
+				}
+			}
 			if (stable) {
 				dev_info(&state->client->dev,
 					"%s(): Phase 1 succeeded, I2C link stable (%d consecutive reads OK)\n",
@@ -4052,8 +4052,8 @@ static int ds5_setup_and_link(struct ds5 *state)
 	int err = 0;
 	struct device *dev = &state->client->dev;
 
-	mutex_lock(&serdes_lock__);
 	ds5_init_global_slots_once();
+	mutex_lock(&serdes_lock__);
 
 	state->ds5_dev = NULL;
 	/* Look for existing DS5 instances */
@@ -4064,8 +4064,7 @@ static int ds5_setup_and_link(struct ds5 *state)
 		match = ds5_inited[i].ds5_primary &&
 			ds5_inited[i].ds5_primary->ser_dev == state->ser_dev;
 		mutex_unlock(&ds5_inited[i].lock);
-		if (match)
-		{ /* Same camera, different stream instance. */
+		if (match) { /* Same camera, different stream instance. */
 			state->serdes_primary = false;
 			state->ds5_dev = &ds5_inited[i];
 			break;