net: wwan: iosm: allow trace port be uninitialized

Collecting modem firmware traces is optional for the regular modem use.
There are not many reasons for aborting device initialization due to an
inability to initialize the trace port and (or) its debugfs interface.
So, demote the initialization failure erro message into a warning and do
not break the initialization sequence in this case. Rework packet
processing and deinitialization so that they do not crash in case of
uninitialized trace port.

This change is mainly a preparation for an upcoming configuration option
introduction that will help disable driver debugfs functionality.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Acked-by: M Chetan Kumar <m.chetan.kumar@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/wwan/iosm/iosm_ipc_imem.c

@@ -272,7 +272,7 @@ static void ipc_imem_dl_skb_process(struct iosm_imem *ipc_imem,
 		if (port_id == IPC_MEM_CTRL_CHL_ID_7)
 			ipc_imem_sys_devlink_notify_rx(ipc_imem->ipc_devlink,
 						       skb);
-		else if (port_id == ipc_imem->trace->chl_id)
+		else if (ipc_is_trace_channel(ipc_imem, port_id))
 			ipc_trace_port_rx(ipc_imem->trace, skb);
 		else
 			wwan_port_rx(ipc_imem->ipc_port[port_id]->iosm_port,
@@ -555,10 +555,8 @@ static void ipc_imem_run_state_worker(struct work_struct *instance)
 	}
 
 	ipc_imem->trace = ipc_trace_init(ipc_imem);
-	if (!ipc_imem->trace) {
-		dev_err(ipc_imem->dev, "trace channel init failed");
-		return;
-	}
+	if (!ipc_imem->trace)
+		dev_warn(ipc_imem->dev, "trace channel init failed");
 
 	ipc_task_queue_send_task(ipc_imem, ipc_imem_send_mdm_rdy_cb, 0, NULL, 0,
 				 false);

drivers/net/wwan/iosm/iosm_ipc_trace.c

@@ -172,6 +172,9 @@ struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem)
  */
 void ipc_trace_deinit(struct iosm_trace *ipc_trace)
 {
+	if (!ipc_trace)
+		return;
+
 	debugfs_remove(ipc_trace->ctrl_file);
 	relay_close(ipc_trace->ipc_rchan);
 	mutex_destroy(&ipc_trace->trc_mutex);

drivers/net/wwan/iosm/iosm_ipc_trace.h

@@ -45,6 +45,11 @@ struct iosm_trace {
 	enum trace_ctrl_mode mode;
 };
 
+static inline bool ipc_is_trace_channel(struct iosm_imem *ipc_mem, u16 chl_id)
+{
+	return ipc_mem->trace && ipc_mem->trace->chl_id == chl_id;
+}
+
 struct iosm_trace *ipc_trace_init(struct iosm_imem *ipc_imem);
 void ipc_trace_deinit(struct iosm_trace *ipc_trace);
 void ipc_trace_port_rx(struct iosm_trace *ipc_trace, struct sk_buff *skb);