RE: [PATCH] mailbox: imx: Add context save/restore for suspend/resume

From: Aisheng Dong
Date: Thu Apr 23 2020 - 22:27:14 EST


> From: Anson Huang <Anson.Huang@xxxxxxx>
> Sent: Friday, April 24, 2020 7:01 AM
>
> For "mem" mode suspend on i.MX8 SoCs, MU settings could be lost because its
> power is off, so save/restore is needed for MU settings during suspend/resume.
> However, the restore can ONLY be done when MU settings are actually lost, for
> the scenario of settings NOT lost in "freeze" mode suspend, since there could be
> still IPC going on multiple CPUs, restoring the MU settings could overwrite the
> TIE by mistake and cause system freeze, so need to make sure ONLY restore the
> MU settings when it is powered off.
>
> Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>

As mentioned before, we'd better keep the original author.

> ---
> drivers/mailbox/imx-mailbox.c | 35
> +++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
>
> diff --git a/drivers/mailbox/imx-mailbox.c b/drivers/mailbox/imx-mailbox.c
> index 97bf0ac..b53cf63 100644
> --- a/drivers/mailbox/imx-mailbox.c
> +++ b/drivers/mailbox/imx-mailbox.c
> @@ -67,6 +67,8 @@ struct imx_mu_priv {
> struct clk *clk;
> int irq;
>
> + u32 xcr;
> +
> bool side_b;
> };
>
> @@ -583,12 +585,45 @@ static const struct of_device_id imx_mu_dt_ids[] =
> { }; MODULE_DEVICE_TABLE(of, imx_mu_dt_ids);
>
> +static int imx_mu_suspend_noirq(struct device *dev) {
> + struct imx_mu_priv *priv = dev_get_drvdata(dev);
> +
> + priv->xcr = imx_mu_read(priv, priv->dcfg->xCR);
> +
> + return 0;
> +}
> +
> +static int imx_mu_resume_noirq(struct device *dev) {
> + struct imx_mu_priv *priv = dev_get_drvdata(dev);
> +
> + /*
> + * ONLY restore MU when context lost, the TIE could
> + * be set during noirq resume as there is MU data
> + * communication going on, and restore the saved
> + * value will overwrite the TIE and cause MU data
> + * send failed, may lead to system freeze. This issue
> + * is observed by testing freeze mode suspend.
> + */
> + if (!imx_mu_read(priv, priv->dcfg->xCR))
> + imx_mu_write(priv, priv->xcr, priv->dcfg->xCR);

This could be separate patch if it aims to fix a specific corner case.

Regards
Aisheng

> +
> + return 0;
> +}
> +
> +static const struct dev_pm_ops imx_mu_pm_ops = {
> + SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_mu_suspend_noirq,
> + imx_mu_resume_noirq)
> +};
> +
> static struct platform_driver imx_mu_driver = {
> .probe = imx_mu_probe,
> .remove = imx_mu_remove,
> .driver = {
> .name = "imx_mu",
> .of_match_table = imx_mu_dt_ids,
> + .pm = &imx_mu_pm_ops,
> },
> };
> module_platform_driver(imx_mu_driver);
> --
> 2.7.4