NOC (interconnect) lockup on i.MX8MP during resume

From: Alexander Stein <alexander.stein@ew.tq-group.com>
To: linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Subject: NOC (interconnect) lockup on i.MX8MP during resume
Date: Thu, 09 Mar 2023 15:57:50 +0100	[thread overview]
Message-ID: <2176690.usQuhbGJ8B@steina-w> (raw)

Hi,

while debugging another issue regarding suspend/resume I noticed that the imx
interconnect driver locks up the system when writing into registers. This
happens during resume of the 'g2' power domain. imx8m_blk_ctrl_power_on()
will eventually call down to imx_icc_node_set(). Using the debug diff furthe
down I get this output:

[   71.493062] imx_icc_node_set: node: VPU G2
[   71.497163] imx_icc_node_set: peak_bw: 1
[   71.501091] imx_icc_node_set: prio: 0x80000303
<freeze here>

Unfortunately there is absolutely no documentation regarding NOC in the
reference manual, so no idea whats happening here.
This is on next-20230309 using imx8mp-tqma8mpql-mba8mpxl.dts with USB
disabled (prevents suspend) and Ethernet-PHY-IRQ disabled (the issue I'm
tackling).
Is there some idea what do in order to support resume on i.MX8MP?

Best regards,
Alexander

---8<---

diff --git a/drivers/interconnect/imx/imx.c b/drivers/interconnect/imx/imx.c
index 979ed610f704..93ec79cc7c06 100644
--- a/drivers/interconnect/imx/imx.c
+++ b/drivers/interconnect/imx/imx.c
@@ -44,13 +44,18 @@ static int imx_icc_node_set(struct icc_node *node)
        u32 prio;
        u64 freq;
 
+       pr_info("%s: node: %s\n", __func__, node->name);
+       pr_info("%s: peak_bw: %u\n", __func__, node->peak_bw);
        if (node_data->setting && node->peak_bw) {
                base = node_data->setting->reg + node_data->imx_provider->noc_base;
                if (node_data->setting->mode == IMX_NOC_MODE_FIXED) {
                        prio = node_data->setting->prio_level;
                        prio = PRIORITY_COMP_MARK | (prio << 8) | prio;
+                       pr_info("%s: prio: %#x\n", __func__, prio);
                        writel(prio, base + IMX_NOC_PRIO_REG);
+                       pr_info("%s: mode: %#x\n", __func__, node_data->setting->mode);
                        writel(node_data->setting->mode, base + IMX_NOC_MODE_REG);
+                       pr_info("%s: ext_control: #%x\n", __func__, node_data->setting->ext_control);
                        writel(node_data->setting->ext_control, base + IMX_NOC_EXT_CTL_REG);
                        dev_dbg(dev, "%s: mode: 0x%x, prio: 0x%x, ext_control: 0x%x\n",
                                node_data->desc->name, node_data->setting->mode, prio,
---8<---

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