linux-kernel - RE: [PATCH 1/4] i3c: master: detach and free device if pre_assign_dyn

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Message-ID: <SN6PR12MB26551F172804D039F3EAA991AEA20@SN6PR12MB2655.namprd12.prod.outlook.com>
Date:   Thu, 29 Aug 2019 13:53:24 +0000
From:   Vitor Soares <Vitor.Soares@...opsys.com>
To:     Boris Brezillon <boris.brezillon@...labora.com>,
        Vitor Soares <Vitor.Soares@...opsys.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-i3c@...ts.infradead.org" <linux-i3c@...ts.infradead.org>,
        "bbrezillon@...nel.org" <bbrezillon@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "Joao.Pinto@...opsys.com" <Joao.Pinto@...opsys.com>,
        Przemyslaw Gaj <pgaj@...ence.com>
Subject: RE: [PATCH 1/4] i3c: master: detach and free device if
 pre_assign_dyn_addr() fails

Hi Boris,

From: Boris Brezillon <boris.brezillon@...labora.com>
Date: Thu, Aug 29, 2019 at 11:41:15

> +Przemek
> 
> Please try to Cc active I3C contributors so they get a chance to
> comment on your patches.

I can do that next time.

> 
> On Thu, 29 Aug 2019 12:19:32 +0200
> Vitor Soares <Vitor.Soares@...opsys.com> wrote:
> 
> > On pre_assing_dyn_addr() the devices that fail:
> >   i3c_master_setdasa_locked()
> >   i3c_master_reattach_i3c_dev()
> >   i3c_master_retrieve_dev_info()
> > 
> > are kept in memory and master->bus.devs list. This makes the i3c devices
> > without a dynamic address are sent on DEFSLVS CCC command. Fix this by
> > detaching and freeing the devices that fail on pre_assign_dyn_addr().
> 
> I don't think removing those entries is a good strategy, as one might
> want to try to use a different dynamic address if the requested one
> is not available.

Do you mean same 'assigned-address' attribute in DT?

If so, it is checked here:

static int i3c_master_bus_init(struct i3c_master_controller *master)
...
	list_for_each_entry(i3cboardinfo, &master->boardinfo.i3c, node) {
		struct i3c_device_info info = {
			.static_addr = i3cboardinfo->static_addr,
		};

		if (i3cboardinfo->init_dyn_addr) {
			status = i3c_bus_get_addr_slot_status(&master->bus,
			^
						i3cboardinfo->init_dyn_addr);
			if (status != I3C_ADDR_SLOT_FREE) {
				ret = -EBUSY;
				goto err_detach_devs;
			}
		}

		i3cdev = i3c_master_alloc_i3c_dev(master, &info);
		if (IS_ERR(i3cdev)) {
			ret = PTR_ERR(i3cdev);
			goto err_detach_devs;
		}

		i3cdev->boardinfo = i3cboardinfo;

		ret = i3c_master_attach_i3c_dev(master, i3cdev);
		if (ret) {
			i3c_master_free_i3c_dev(i3cdev);
			goto err_detach_devs;
		}
	}
...

and later if it fails i3c_master_pre_assign_dyn_addr(), the device can 
participate in Enter Dynamic Address Assignment process.
I may need to check the boardinfo->init_dyn_addr status on 
i3c_master_add_i3c_dev_locked before i3c_master_setnewda_locked().

> Why not simply skipping entries that have ->dyn_addr
> set to 0 when preparing a DEFSLVS frame

I considered that solution too but if the device isn't enumerated why 
should it be attached and kept in memory? Anyway we have i3c_boardinfo 
with DT information.

> 
> > 
> > Signed-off-by: Vitor Soares <vitor.soares@...opsys.com>
> > ---
> >  drivers/i3c/master.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> > index 5f4bd52..4d29e1f 100644
> > --- a/drivers/i3c/master.c
> > +++ b/drivers/i3c/master.c
> > @@ -1438,7 +1438,7 @@ static void i3c_master_pre_assign_dyn_addr(struct i3c_dev_desc *dev)
> >  	ret = i3c_master_setdasa_locked(master, dev->info.static_addr,
> >  					dev->boardinfo->init_dyn_addr);
> >  	if (ret)
> > -		return;
> > +		goto err_detach_dev;
> >  
> >  	dev->info.dyn_addr = dev->boardinfo->init_dyn_addr;
> >  	ret = i3c_master_reattach_i3c_dev(dev, 0);
> > @@ -1453,6 +1453,10 @@ static void i3c_master_pre_assign_dyn_addr(struct i3c_dev_desc *dev)
> >  
> >  err_rstdaa:
> >  	i3c_master_rstdaa_locked(master, dev->boardinfo->init_dyn_addr);
> > +
> > +err_detach_dev:
> > +	i3c_master_detach_i3c_dev(dev);
> > +	i3c_master_free_i3c_dev(dev);
> 
> We certainly shouldn't detach/free the i3c_dev_desc from here. If it
> has to be done somewhere (which I'd like to avoid), it should be done
> in i3c_master_bus_init() (i3c_master_pre_assign_dyn_addr() should be
> converted to return an int in that case).

I can change it to return an error. 

> 
> >  }
> >  
> >  static void
> > @@ -1647,7 +1651,7 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
> >  	enum i3c_addr_slot_status status;
> >  	struct i2c_dev_boardinfo *i2cboardinfo;
> >  	struct i3c_dev_boardinfo *i3cboardinfo;
> > -	struct i3c_dev_desc *i3cdev;
> > +	struct i3c_dev_desc *i3cdev, *i3ctmp;
> >  	struct i2c_dev_desc *i2cdev;
> >  	int ret;
> >  
> > @@ -1746,7 +1750,8 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
> >  	 * Pre-assign dynamic address and retrieve device information if
> >  	 * needed.
> >  	 */
> > -	i3c_bus_for_each_i3cdev(&master->bus, i3cdev)
> > +	list_for_each_entry_safe(i3cdev, i3ctmp, &master->bus.devs.i3c,
> > +				 common.node)
> >  		i3c_master_pre_assign_dyn_addr(i3cdev);
> >  
> >  	ret = i3c_master_do_daa(master);

Thank for your feedback.

Best regards,
Vitor Soares