RE: [PATCH v1] i3c: master: Enable runtime PM for master controller

From: Joshua Yeong <joshua.yeong@starfivetech.com>
To: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>,
	"alexandre.belloni@bootlin.com" <alexandre.belloni@bootlin.com>,
	"linux-i3c@lists.infradead.org" <linux-i3c@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "andersson@kernel.org" <andersson@kernel.org>,
	"vkoul@kernel.org" <vkoul@kernel.org>,
	"manivannan.sadhasivam@linaro.org"
	<manivannan.sadhasivam@linaro.org>
Subject: RE: [PATCH v1] i3c: master: Enable runtime PM for master controller
Date: Fri, 15 Mar 2024 08:05:55 +0000	[thread overview]
Message-ID: <SH0PR01MB08419B8683E8F2DD05A791BBF928A@SH0PR01MB0841.CHNPR01.prod.partner.outlook.cn> (raw)
In-Reply-To: <b61f5f4a-7931-411d-9519-bbff1b7fd6f9@quicinc.com>

> -----Original Message-----
> From: linux-i3c <linux-i3c-bounces@lists.infradead.org> On Behalf Of Mukesh
> Kumar Savaliya
> Sent: Monday, March 11, 2024 1:30 AM
> To: alexandre.belloni@bootlin.com; linux-i3c@lists.infradead.org; linux-
> kernel@vger.kernel.org
> Cc: andersson@kernel.org; vkoul@kernel.org;
> manivannan.sadhasivam@linaro.org
> Subject: Re: [PATCH v1] i3c: master: Enable runtime PM for master controller
> 
> A Gentle reminder ! As i was not part of the linux-i3c group before raising this
> gerrit, might not went into right folder.
> 
> On 2/28/2024 3:04 PM, Mukesh Kumar Savaliya wrote:
> > Enable runtime PM for i3c master node during master registration time.
> >
> > Sometimes i3c client device driver may want to control the PM of the
> > parent (master) to perform the transactions and save the power in an
> > efficient way by controlling the session. Hence device can call PM
> > APIs by passing the parent node.
> >
> > Here, I3C target device when calls pm_runtime_get_sync(dev->parent)
> > couldn't invoke master drivers runtime PM callback registered by the
> > master driver because parent's PM status was disabled in the Master
> > node.
> >
> > Also call pm_runtime_no_callbacks() and pm_suspend_ignore_children()
> > for the master node to not have any callback addition and ignore the
> > children to have runtime PM work just locally in the driver. This
> > should be generic and common change for all i3c devices and should not
> > have any other impact.
> >
> > With these changes, I3C client device works and able to invoke master
> > driver registered runtime PM callbacks.
> >
> > Signed-off-by: Mukesh Kumar Savaliya <quic_msavaliy@quicinc.com>
> > ---
> >   drivers/i3c/master.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index
> > 3afa530c5e32..a3dc88974f92 100644
> > --- a/drivers/i3c/master.c
> > +++ b/drivers/i3c/master.c
> > @@ -13,6 +13,7 @@
> >   #include <linux/kernel.h>
> >   #include <linux/list.h>
> >   #include <linux/of.h>
> > +#include <linux/pm_runtime.h>
> >   #include <linux/slab.h>
> >   #include <linux/spinlock.h>
> >   #include <linux/workqueue.h>
> > @@ -2812,6 +2813,10 @@ int i3c_master_register(struct
> > i3c_master_controller *master,
> >
> >   	i3c_bus_notify(i3cbus, I3C_NOTIFY_BUS_ADD);
> >
> > +	pm_runtime_no_callbacks(&master->dev);
> > +	pm_suspend_ignore_children(&master->dev, true);
> > +	pm_runtime_enable(&master->dev);
> > +

Will runtime pm impact on ibi request from target?

> >   	/*
> >   	 * We're done initializing the bus and the controller, we can now
> >   	 * register I3C devices discovered during the initial DAA.
> > @@ -2849,6 +2854,7 @@ void i3c_master_unregister(struct
> i3c_master_controller *master)
> >   	i3c_master_i2c_adapter_cleanup(master);
> >   	i3c_master_unregister_i3c_devs(master);
> >   	i3c_master_bus_cleanup(master);
> > +	pm_runtime_disable(&master->dev);
> >   	device_unregister(&master->dev);
> >   }
> >   EXPORT_SYMBOL_GPL(i3c_master_unregister);
> 
> --
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> linux-i3c@lists.infradead.org
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