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

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Message-ID: <20230803155541.nwsfwobfkbpefoyw@dhruva>
Date:   Thu, 3 Aug 2023 21:25:41 +0530
From:   Dhruva Gole <d-gole@...com>
To:     Andrew Davis <afd@...com>
CC:     Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
        "Santosh Shilimkar" <ssantosh@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Praneeth Bajjuri <praneeth@...com>,
        Tony Lindgren <tony@...mide.com>,
        Dave Gerlach <d-gerlach@...com>,
        Vibhore Vardhan <vibhore@...com>, Georgi Vlaev <g-vlaev@...com>
Subject: Re: [PATCH V6 4/4] firmware: ti_sci: Introduce system suspend resume
 support

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@...com>
> > Signed-off-by: Dave Gerlach <d-gerlach@...com>
> > Signed-off-by: Vibhore Vardhan <vibhore@...com>
> > Signed-off-by: Georgi Vlaev <g-vlaev@...com>
> > Signed-off-by: Dhruva Gole <d-gole@...com>
> > ---
> >   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

> 
> 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);

-- 
Best regards,
Dhruva Gole <d-gole@...com>