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SubjectRe: [PATCH V6 4/4] firmware: ti_sci: Introduce system suspend resume support
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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@ti.com>
>>> Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
>>> Signed-off-by: Vibhore Vardhan <vibhore@ti.com>
>>> Signed-off-by: Georgi Vlaev <g-vlaev@ti.com>
>>> Signed-off-by: Dhruva Gole <d-gole@ti.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
>

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);
>

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