[PATCH V4 6/6] remoteproc: imx_rproc: request mbox channel later

["Peng Fan (OSS)" <peng.fan@xxxxxxxxxxx>]

From: Peng Fan <peng.fan@xxxxxxx>

It is possible that when remote processor crash, the communication
channel will be broken with garbage value in mailbox, such as
when Linux is issuing a message through mailbox, remote processor
crashes, we need free & rebuild the mailbox channels to make sure
no garbage value in mailbox channels.

So move the request/free to start/stop for managing remote procesosr in
Linux, move to attach/detach for remote processor is out of control of
Linux.

Previous, we just request mbox when attach for CM4 boot early before
Linux, but if mbox defer probe, remoteproc core will do resource cleanup
and corrupt resource table for later probe.

So move request mbox ealier and still keep mbox request when attach
for self recovery case, but keep a check when request/free mbox.

Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
---
 drivers/remoteproc/imx_rproc.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
index f129cc840931..503435ad1f11 100644
--- a/drivers/remoteproc/imx_rproc.c
+++ b/drivers/remoteproc/imx_rproc.c
@@ -84,6 +84,8 @@ struct imx_rproc_mem {
 #define ATT_CORE_MASK   0xffff
 #define ATT_CORE(I)     BIT((I))
 
+static int imx_rproc_xtr_mbox_init(struct rproc *rproc);
+static void imx_rproc_free_mbox(struct rproc *rproc);
 static int imx_rproc_detach_pd(struct rproc *rproc);
 
 struct imx_rproc {
@@ -357,6 +359,10 @@ static int imx_rproc_start(struct rproc *rproc)
 	struct arm_smccc_res res;
 	int ret;
 
+	ret = imx_rproc_xtr_mbox_init(rproc);
+	if (ret)
+		return ret;
+
 	switch (dcfg->method) {
 	case IMX_RPROC_MMIO:
 		ret = regmap_update_bits(priv->regmap, dcfg->src_reg, dcfg->src_mask,
@@ -407,6 +413,8 @@ static int imx_rproc_stop(struct rproc *rproc)
 
 	if (ret)
 		dev_err(dev, "Failed to stop remote core\n");
+	else
+		imx_rproc_free_mbox(rproc);
 
 	return ret;
 }
@@ -592,7 +600,7 @@ static void imx_rproc_kick(struct rproc *rproc, int vqid)
 
 static int imx_rproc_attach(struct rproc *rproc)
 {
-	return 0;
+	return imx_rproc_xtr_mbox_init(rproc);
 }
 
 static struct resource_table *imx_rproc_get_loaded_rsc_table(struct rproc *rproc, size_t *table_sz)
@@ -721,6 +729,9 @@ static int imx_rproc_xtr_mbox_init(struct rproc *rproc)
 	struct mbox_client *cl;
 	int ret;
 
+	if (priv->tx_ch && priv->rx_ch)
+		return 0;
+
 	if (!of_get_property(dev->of_node, "mbox-names", NULL))
 		return 0;
 
@@ -753,8 +764,15 @@ static void imx_rproc_free_mbox(struct rproc *rproc)
 {
 	struct imx_rproc *priv = rproc->priv;
 
-	mbox_free_channel(priv->tx_ch);
-	mbox_free_channel(priv->rx_ch);
+	if (priv->tx_ch) {
+		mbox_free_channel(priv->tx_ch);
+		priv->tx_ch = NULL;
+	}
+
+	if (priv->rx_ch) {
+		mbox_free_channel(priv->rx_ch);
+		priv->rx_ch = NULL;
+	}
 }
 
 static void imx_rproc_put_scu(struct rproc *rproc)
@@ -781,6 +799,8 @@ static int imx_rproc_partition_notify(struct notifier_block *nb,
 	if (!((event & BIT(priv->rproc_pt)) && (*(u8 *)group == IMX_SC_IRQ_GROUP_REBOOTED)))
 		return 0;
 
+	imx_rproc_free_mbox(priv->rproc);
+
 	rproc_report_crash(priv->rproc, RPROC_WATCHDOG);
 
 	pr_info("Partition%d reset!\n", priv->rproc_pt);
-- 
2.25.1