Re: [PATCH v2 2/2] remoteproc: imx_rproc: handle system off for i.MX7ULP

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Fri, Jul 19, 2024 at 04:49:04PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
> 
> The i.MX7ULP Cortex-A7 is under control of Cortex-M4. The i.MX7ULP Linux
> poweroff and restart rely on rpmsg driver to send a message to Cortex-M4
> firmware. Then Cortex-A7 could poweroff or restart by Cortex-M4 to
> configure the i.MX7ULP power controller properly.
> 
> However the reboot and restart kernel common code use atomic notifier,
> so with blocking tx mailbox will trigger kernel dump, because of
> blocking mailbox will use wait_for_completion_timeout. In such case,
> linux no need to wait for completion.
> 
> Current patch is to use non-blocking tx mailbox channel when system
> is going to poweroff or restart.
> 
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---
>  drivers/remoteproc/imx_rproc.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index 01cf1dfb2e87..e1abf110abc9 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -18,6 +18,7 @@
>  #include <linux/of_reserved_mem.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_domain.h>
> +#include <linux/reboot.h>
>  #include <linux/regmap.h>
>  #include <linux/remoteproc.h>
>  #include <linux/workqueue.h>
> @@ -114,6 +115,7 @@ struct imx_rproc {
>  	u32				entry;		/* cpu start address */
>  	u32				core_index;
>  	struct dev_pm_domain_list	*pd_list;
> +	struct sys_off_data		data;

What is this for?  I don't see it used in this patch.

>  };
>  
>  static const struct imx_rproc_att imx_rproc_att_imx93[] = {
> @@ -1050,6 +1052,22 @@ static int imx_rproc_clk_enable(struct imx_rproc *priv)
>  	return 0;
>  }
>  
> +static int imx_rproc_sys_off_handler(struct sys_off_data *data)
> +{
> +	struct rproc *rproc = data->cb_data;
> +	int ret;
> +
> +	imx_rproc_free_mbox(rproc);
> +
> +	ret = imx_rproc_xtr_mbox_init(rproc, false);
> +	if (ret) {
> +		dev_err(&rproc->dev, "Failed to request non-blocking mbox\n");
> +		return NOTIFY_BAD;
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
>  static int imx_rproc_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -1104,6 +1122,24 @@ static int imx_rproc_probe(struct platform_device *pdev)
>  	if (rproc->state != RPROC_DETACHED)
>  		rproc->auto_boot = of_property_read_bool(np, "fsl,auto-boot");
>  
> +	if (of_device_is_compatible(dev->of_node, "fsl,imx7ulp-cm4")) {
> +		ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_POWER_OFF_PREPARE,
> +						    SYS_OFF_PRIO_DEFAULT,
> +						    imx_rproc_sys_off_handler, rproc);

Why does the mailbox needs to be set up again when the system is going down...

> +		if (ret) {
> +			dev_err(dev, "register power off handler failure\n");
> +			goto err_put_clk;
> +		}
> +
> +		ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_RESTART_PREPARE,
> +						    SYS_OFF_PRIO_DEFAULT,
> +						    imx_rproc_sys_off_handler, rproc);

... and why does it need to be free'd when the system is going up?

> +		if (ret) {
> +			dev_err(dev, "register restart handler failure\n");
> +			goto err_put_clk;
> +		}
> +	}
> +
>  	ret = rproc_add(rproc);
>  	if (ret) {
>  		dev_err(dev, "rproc_add failed\n");
> 
> -- 
> 2.37.1
> 
>