NVIDIA: VR: SAUCE: firmware: smccc: lfa: handle LFA_BUSY in PRIME and ACTIVATE

DEN0147 §2.6: LFA_ACTIVATE can return LFA_BUSY when the firmware
postpones the activation. Although the rwsem in this driver prevents
concurrent ACTIVATE calls from kernel space, an external agent or
internal firmware state may still produce LFA_BUSY. Add an explicit
retry loop (same budget and delay as CALL_AGAIN) so the code does not
silently treat a retriable condition as a terminal failure. Catching
LFA_BUSY explicitly also surfaces potential firmware or driver bugs.

DEN0147 §2.5: LFA_PRIME returning LFA_BUSY means another CPU is
running LFA_PRIME concurrently. This driver never issues parallel PRIME,
so this is unexpected; log pr_warn and return so the caller can surface
the anomaly rather than swallowing it in the generic error path.

Signed-off-by: Vedashree Vidwans <vvidwans@nvidia.com>
Signed-off-by: Nirmoy Das <nirmoyd@nvidia.com>

Author: nirmoy

drivers/firmware/smccc/lfa_fw.c

@@ -371,6 +371,23 @@ static int activate_fw_image(struct fw_image *image)
 		ret = -LFA_TIMED_OUT;
 	}
 
+	/*
+	 * DEN0147 §2.6: LFA_BUSY means activation was postponed by firmware
+	 * and must be retried. Although the rwsem prevents concurrent ACTIVATE
+	 * from this driver, an external agent or firmware-internal state may
+	 * still return LFA_BUSY. Handle it explicitly so it is not silently
+	 * treated as a terminal failure — catching it here may also indicate a
+	 * bug in the driver or firmware.
+	 */
+	if (ret == -LFA_BUSY) {
+		if (ktime_before(ktime_get(), end)) {
+			msleep_interruptible(LFA_ACTIVATE_DELAY_MS);
+			goto retry;
+		}
+
+		ret = -LFA_TIMED_OUT;
+	}
+
 	lfa_cancel(image);
 
 	pr_err("LFA_ACTIVATE for image %s failed: %s\n",
@@ -406,6 +423,17 @@ static int prime_fw_image(struct fw_image *image)
 	arm_smccc_1_2_invoke(&reg, &res);
 	up_read(&smc_lock);
 
+	/*
+	 * DEN0147 §2.5: LFA_BUSY from PRIME means another CPU is concurrently
+	 * running LFA_PRIME. This driver never issues parallel PRIME, so this
+	 * is unexpected and likely indicates a firmware or driver bug.
+	 */
+	if ((long)res.a0 == -LFA_BUSY) {
+		pr_warn("LFA_PRIME for image %s returned LFA_BUSY (concurrent PRIME unexpected; possible firmware or driver bug)\n",
+			get_image_name(image));
+		return res.a0;
+	}
+
 	if ((long)res.a0 < 0) {
 		pr_err("LFA_PRIME for image %s failed: %s\n",
 		       get_image_name(image),