NOC (interconnect) lockup on i.MX8MP during resume

[Adam Ford]

On Thu, Mar 9, 2023 at 9:11 AM Alexander Stein
<alexander.stein at ew.tq-group.com> wrote:
>
> 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?

I haven't played with suspend-resume myself, but there was a thread
[1] with discussions about fixing a race condition on the imx8mp
interconnect.

adam

[1] - https://lore.kernel.org/lkml/20230201101559.15529-5-johan+linaro@kernel.org/



>
> 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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