[PATCH 1/2] remoteproc: qcom: pas: Decide early_boot attach at probe time

[Shawn Guo]

For early_boot subsystems, probe unconditionally marks the rproc
RPROC_DETACHED and qcom_pas_attach() discovers from SMP2P whether the
bootloader actually started the remote. If it did not, attach sets the
state back to RPROC_OFFLINE and fails, expecting the core to boot the
firmware instead. The core does not do that: rproc_boot() treats the
attach failure as fatal and the remote is never started.

This is hit on Nord with firmware where XBL no longer brings ADSP out
of reset. The remote never publishes its inbound SMP2P entries, so the
very first state read fails (debug print below) and the ADSP stays down:

  qcom_q6v5_pas 4c00000.remoteproc: Failed to get fatal_irq state: -19
  remoteproc remoteproc0: can't attach to rproc adsp: -19

The ready, stop-ack and sysmon shutdown-ack signals cannot change while
Linux has not yet interacted with the remote, so there is no reason to
defer the decision to attach time. Check them in probe and only mark
the rproc RPROC_DETACHED when the remote is up and has not been asked
to stop; otherwise leave it RPROC_OFFLINE so the regular firmware boot
path is taken. The ready state is read first so that a missing SMP2P
entry -ENODEV is treated as "not running" before sysmon is queried.

qcom_pas_attach() keeps only the fatal check, since that is the one
signal that has to be acted upon once the rproc is attached.

Assisted-by: LLM
Signed-off-by: Shawn Guo <shengchao.guo@xxxxxxxxxxxxxxxx>
---
 drivers/remoteproc/qcom_q6v5_pas.c | 64 +++++++++++++++---------------
 1 file changed, 33 insertions(+), 31 deletions(-)

diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
index 2e1e39826ffa..8f3d45c604c9 100644
--- a/drivers/remoteproc/qcom_q6v5_pas.c
+++ b/drivers/remoteproc/qcom_q6v5_pas.c
@@ -550,9 +550,7 @@ static unsigned long qcom_pas_panic(struct rproc *rproc)
 static int qcom_pas_attach(struct rproc *rproc)
 {
 	struct qcom_pas *pas = rproc->priv;
-	bool ready_state;
 	bool crash_state;
-	bool stop_state;
 	int ret;
 
 	pas->q6v5.handover_issued = true;
@@ -570,42 +568,46 @@ static int qcom_pas_attach(struct rproc *rproc)
 		goto disable_running;
 	}
 
-	ret = irq_get_irqchip_state(pas->q6v5.stop_irq,
-				    IRQCHIP_STATE_LINE_LEVEL, &stop_state);
-	if (ret)
-		goto disable_running;
-
-	if (stop_state || qcom_sysmon_shutdown_irq_state(pas->sysmon)) {
-		dev_info(pas->dev, "Subsystem found stop state set. Falling back to start.\n");
-		goto unroll_attach;
-	}
-
-	ret = irq_get_irqchip_state(pas->q6v5.ready_irq,
-				    IRQCHIP_STATE_LINE_LEVEL, &ready_state);
-	if (ret)
-		goto disable_running;
-
-	if (unlikely(!ready_state)) {
-		/*
-		 * The bootloader may not support early boot, mark the state as
-		 * RPROC_OFFLINE so that the PAS driver can load the firmware and
-		 * start the remoteproc.
-		 */
-		dev_err(pas->dev, "Failed to get subsystem ready interrupt\n");
-		goto unroll_attach;
-	}
-
 	return 0;
 
-unroll_attach:
-	pas->rproc->state = RPROC_OFFLINE;
-	ret = -EINVAL;
 disable_running:
 	pas->q6v5.running = false;
 
 	return ret;
 }
 
+/*
+ * The bootloader may or may not have started the subsystem. Inspect the
+ * SMP2P state, which is static until Linux interacts with the remote, to
+ * decide whether to attach or to load and start the firmware.
+ */
+static bool qcom_pas_is_running(struct qcom_pas *pas)
+{
+	bool ready_state;
+	bool stop_state;
+	int ret;
+
+	/*
+	 * Check ready first: if the remote never published its SMP2P
+	 * entries the state read fails with -ENODEV.
+	 */
+	ret = irq_get_irqchip_state(pas->q6v5.ready_irq,
+				    IRQCHIP_STATE_LINE_LEVEL, &ready_state);
+	if (ret || !ready_state) {
+		dev_info(pas->dev, "Subsystem not running. Falling back to start.\n");
+		return false;
+	}
+
+	ret = irq_get_irqchip_state(pas->q6v5.stop_irq,
+				    IRQCHIP_STATE_LINE_LEVEL, &stop_state);
+	if (ret || stop_state || qcom_sysmon_shutdown_irq_state(pas->sysmon)) {
+		dev_info(pas->dev, "Subsystem found stop state set. Falling back to start.\n");
+		return false;
+	}
+
+	return true;
+}
+
 static void qcom_pas_coredump(struct rproc *rproc)
 {
 	struct qcom_pas *pas = rproc->priv;
@@ -1024,7 +1026,7 @@ static int qcom_pas_probe(struct platform_device *pdev)
 	if (pas->dtb_pas_id)
 		pas->dtb_pas_ctx->use_tzmem = desc->needs_tzmem || rproc->has_iommu;
 
-	if (desc->early_boot)
+	if (desc->early_boot && qcom_pas_is_running(pas))
 		pas->rproc->state = RPROC_DETACHED;
 
 	ret = qcom_pas_setup_tmd(pas, desc);
-- 
2.43.0