> Subject: Re: [PATCH v2 2/2] remoteproc: imx_rproc: handle system off
> for i.MX7ULP
>
> On Tue, Jul 30, 2024 at 08:06:22AM +0000, Peng Fan wrote:
> > > Subject: Re: [PATCH v2 2/2] remoteproc: imx_rproc: handle system
> off
> > > for i.MX7ULP
> > >
> > > On Fri, Jul 19, 2024 at 04:49:04PM +0800, Peng Fan (OSS) wrote:
> > > > From: Peng Fan <peng.fan@xxxxxxx>
> > > >
> > > > 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@xxxxxxx>
> > > > ---
> > > > 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.
> >
> > Oh, it was added when I was developing this feature, but in the end
> > this seems not needed.
> >
> > >
> > > > };
> > > >
> > > > 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...
> >
> > As wrote in commit message:
> > "i.MX7ULP Linux poweroff and restart rely on rpmsg driver to send a
> > message," so need to set up mailbox in non-blocking way to send a
> > message to M4 side.
> >
> > >
> > > > + 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?
> >
> >
> > Sorry, I not get your point. The free is in imx_rproc_sys_off_handler.
> > During system booting, the mailbox is not freed.
>
> Why is the same operation done at both startup and shutdown - that is
> not clear.
The below commit shows request/free done in startup and shutdown.
Hope this explains what you ask.
commit 99b142cf7191b08adcd23f700ea0a3d7dffdd0c1
Author: Peng Fan <peng.fan@xxxxxxx>
Date: Fri Oct 21 12:15:25 2022 +0800
remoteproc: imx_rproc: Request mbox channel later
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.
>
> I am currently away from the office, returning on August 12th. As such
> I will not be following up on this thread until then.
sure. Thanks for letting me know.
Thanks,
Peng.
>
> >
> > Thanks,
> > Peng.
> >
> > >
> > > > + 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
> > > >
> > > >
