[PATCH 2/3] i3c: mipi-i3c-hci: Add optional System Suspend support

[David Nyström]

On Mon, 19 Jan 2026, Adrian Hunter wrote:

> On 19/01/2026 08:31, David Nyström wrote:
>>
>>
>> On Fri, 16 Jan 2026, Adrian Hunter wrote:
>>
>>> Add system suspend callbacks.  Implement them by forcing runtime PM.
>>> Consequently bail out if Runtime PM is not allowed.
>>>
>>> On resume from System Suspend (suspend to RAM), rerun Dynamic Address
>>> Assignment to restore addresses for devices that may have lost power.
>>>
>>> On resume from System Hibernation (suspend to disk), use the new
>>> i3c_master_restore_daa() helper which additionally handles the case where
>>> devices are assigned different dynamic addresses after a hibernation boot.
>>
>> Why do you make this distinction ?
>> RSTDAA+DAA during boot is motivated by that uboot might have assigned addresses.
>> Why would we need to behave differently in suspend and suspend-to-disk?
>
> Because, in the case of suspend-to-disk, there is a complete
> boot process in between.
>
>> Its fair to assume that I3C devices might have been powered off in suspend too, right ?
>
> Hibernation is quite different.  Briefly:
>
> Entry
> 	ops->freeze
> 	create image
> 	ops->thaw
> 	write image
> 	ops->poweroff
>
> Exit
> 	boot			<- address assignment not guaranteed to be the same as previous boot
> 	ops->freeze
> 	restore image
> 	ops->restore		<- deal with I3C devices that may have different addresses

OK, so bootloader might have messed things up for us again.
Thanks for elaborating.

>>
>>> Signed-off-by: Adrian Hunter <adrian.hunter at intel.com>
>>> ---
>>> drivers/i3c/master/mipi-i3c-hci/core.c | 53 ++++++++++++++++++++++++++
>>> 1 file changed, 53 insertions(+)
>>>
>>> diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
>>> index 02c5a133e329..b972d8bc81e6 100644
>>> --- a/drivers/i3c/master/mipi-i3c-hci/core.c
>>> +++ b/drivers/i3c/master/mipi-i3c-hci/core.c
>>> @@ -769,6 +769,53 @@ static int i3c_hci_runtime_resume(struct device *dev)
>>>     return 0;
>>> }
>>>
>>> +static int i3c_hci_suspend(struct device *dev)
>>> +{
>>> +    struct i3c_hci *hci = dev_get_drvdata(dev);
>>> +
>>> +    if (!(hci->quirks & HCI_QUIRK_RPM_ALLOWED))
>>> +        return 0;
>>> +
>>> +    return pm_runtime_force_suspend(dev);
>>> +}
>>> +
>>> +static int i3c_hci_resume_common(struct device *dev, bool restore)
>>> +{
>>> +    struct i3c_hci *hci = dev_get_drvdata(dev);
>>> +    int ret;
>>> +
>>> +    if (!(hci->quirks & HCI_QUIRK_RPM_ALLOWED))
>>> +        return 0;
>>> +
>>> +    ret = pm_runtime_force_resume(dev);
>>> +    if (ret)
>>> +        return ret;
>>> +
>>> +    if (restore)
>>> +        ret = i3c_master_restore_daa(&hci->master);
>>> +    else
>>> +        ret = i3c_master_do_daa(&hci->master);
>>> +
>>> +    if (ret)
>>> +        dev_err(dev, "Dynamic Address Assignment failed on resume, error %d\n", ret);
>>> +
>>> +    /*
>>> +     * I3C devices may have retained their dynamic address anyway. Do not
>>> +     * fail the resume because of DAA error.
>>> +     */
>>> +    return 0;
>>> +}
>>> +
>>> +static int i3c_hci_resume(struct device *dev)
>>> +{
>>> +    return i3c_hci_resume_common(dev, false);
>>> +}
>>> +
>>> +static int i3c_hci_restore(struct device *dev)
>>> +{
>>> +    return i3c_hci_resume_common(dev, true);
>>> +}
>>> +
>>> #define DEFAULT_AUTOSUSPEND_DELAY_MS 1000
>>>
>>> static void i3c_hci_rpm_enable(struct device *dev)
>>> @@ -945,6 +992,12 @@ static const struct platform_device_id i3c_hci_driver_ids[] = {
>>> MODULE_DEVICE_TABLE(platform, i3c_hci_driver_ids);
>>>
>>> static const struct dev_pm_ops i3c_hci_pm_ops = {
>>> +    .suspend  = pm_sleep_ptr(i3c_hci_suspend),
>>> +    .resume   = pm_sleep_ptr(i3c_hci_resume),
>>> +    .freeze   = pm_sleep_ptr(i3c_hci_suspend),
>>> +    .thaw     = pm_sleep_ptr(i3c_hci_resume),
>>> +    .poweroff = pm_sleep_ptr(i3c_hci_suspend),
>>> +    .restore  = pm_sleep_ptr(i3c_hci_restore),
>>>     RUNTIME_PM_OPS(i3c_hci_runtime_suspend, i3c_hci_runtime_resume, NULL)
>>> };
>>>
>>> -- 
>>> 2.51.0
>>>
>>>
>>> -- 
>>> linux-i3c mailing list
>>> linux-i3c at lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-i3c
>>>
>
>
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