Re: [PATCH V6 4/4] firmware: ti_sci: Introduce system suspend resume support

[Andrew Davis]

On 8/3/23 10:55 AM, Dhruva Gole wrote:
> On Aug 03, 2023 at 10:26:32 -0500, Andrew Davis wrote:
> > On 8/3/23 1:42 AM, Dhruva Gole wrote:
> > > Introduce system suspend resume calls that will allow the ti_sci
> > > driver to support deep sleep low power mode when the user space issues a
> > > suspend to mem.
> > >
> > > Also, write a ti_sci_prepare_system_suspend call to be used in the driver
> > > suspend handler to allow the system to identify the low power mode being
> > > entered and if necessary, send TISCI_MSG_PREPARE_SLEEP with information
> > > about the mode is being entered and the address for allocated memory for
> > > storing the context during Deep Sleep.
> > >
> > > We're using "pm_suspend_target_state" to map the kernel's target suspend
> > > state to SysFW low power mode. Make sure this is available only when
> > > CONFIG_SUSPEND is enabled.
> > >
> > > Co-developed-by: Dave Gerlach <d-gerlach@xxxxxx>
> > > Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
> > > Signed-off-by: Vibhore Vardhan <vibhore@xxxxxx>
> > > Signed-off-by: Georgi Vlaev <g-vlaev@xxxxxx>
> > > Signed-off-by: Dhruva Gole <d-gole@xxxxxx>
> > > ---
> > >    drivers/firmware/ti_sci.c | 63 +++++++++++++++++++++++++++++++++++++++
> > >    1 file changed, 63 insertions(+)
> [..snip..]
> > > +static int ti_sci_suspend(struct device *dev)
> > > +{
> > > +	struct ti_sci_info *info = dev_get_drvdata(dev);
> > > +	int ret;
> > > +
> > > +	ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_ENABLE);
> >
> > After this the will the IOs be in isolation? Or does the firmware wait
> > until power down begins later?
>
>  From what I understand,
> IOs will be in isolation immediately

That is what I understand too, so then any device that may need to do some
external communication for its suspend will not function, this must be the
last driver _suspend() the system calls, how do you enforce that?

Andrew

> > Andrew
> >
> > > +	if (ret)
> > > +		return ret;
> > > +	dev_dbg(dev, "%s: set I/O isolation: %d\n", __func__, ret);
> > > +
> > > +	ret = ti_sci_prepare_system_suspend(info);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int ti_sci_resume(struct device *dev)
> > > +{
> > > +	struct ti_sci_info *info = dev_get_drvdata(dev);
> > > +	int ret;
> > > +
> > > +	ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_DISABLE);
> > > +	if (ret)
> > > +		return ret;
> > > +	dev_dbg(dev, "%s: disable I/O isolation: %d\n", __func__, ret);
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static DEFINE_SIMPLE_DEV_PM_OPS(ti_sci_pm_ops, ti_sci_suspend, ti_sci_resume);
> > > +
> > >    static int ti_sci_init_suspend(struct platform_device *pdev,
> > >    			       struct ti_sci_info *info)
> > >    {
> > > @@ -3759,6 +3821,7 @@ static struct platform_driver ti_sci_driver = {
> > >    	.driver = {
> > >    		   .name = "ti-sci",
> > >    		   .of_match_table = of_match_ptr(ti_sci_of_match),
> > > +		   .pm = &ti_sci_pm_ops,
> > >    	},
> > >    };
> > >    module_platform_driver(ti_sci_driver);