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Date:   Sun, 23 Aug 2020 12:14:30 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     Parshuram Thombare <pthombar@...ence.com>, <bbrezillon@...nel.org>,
        mparab@...ence.com, praneeth@...com, pgaj@...ence.com
Cc:     <vitor.soares@...opsys.com>, linux-kernel@...r.kernel.org,
        linux-i3c@...ts.infradead.org
Subject: Re: [PATCH v4] i3c: master: fix for SETDASA and DAA process

On Sun, 23 Aug 2020 11:59:18 +0200
Boris Brezillon <boris.brezillon@...labora.com> wrote:


> > -static void i3c_master_pre_assign_dyn_addr(struct i3c_dev_desc *dev)
> > +static int i3c_master_early_i3c_dev_add(struct i3c_master_controller *master,
> > +					  struct i3c_dev_boardinfo *boardinfo)
> >  {
> > -	struct i3c_master_controller *master = i3c_dev_get_master(dev);
> > +	struct i3c_device_info info = {
> > +		.static_addr = boardinfo->static_addr,
> > +	};
> > +	struct i3c_dev_desc *i3cdev;
> >  	int ret;
> >  
> > -	if (!dev->boardinfo || !dev->boardinfo->init_dyn_addr ||
> > -	    !dev->boardinfo->static_addr)
> > -		return;
> > +	i3cdev = i3c_master_alloc_i3c_dev(master, &info);
> > +	if (IS_ERR(i3cdev))
> > +		return -ENOMEM;
> >  
> > -	ret = i3c_master_setdasa_locked(master, dev->info.static_addr,
> > -					dev->boardinfo->init_dyn_addr);
> > +	i3cdev->boardinfo = boardinfo;
> > +
> > +	ret = i3c_master_attach_i3c_dev(master, i3cdev);
> >  	if (ret)
> > -		return;
> > +		goto err_attach;
> > +
> > +	ret = i3c_master_setdasa_locked(master, i3cdev->info.static_addr,
> > +					i3cdev->boardinfo->init_dyn_addr);
> > +	if (ret)
> > +		goto err_setdasa;
> >  
> > -	dev->info.dyn_addr = dev->boardinfo->init_dyn_addr;
> > -	ret = i3c_master_reattach_i3c_dev(dev, 0);
> > +	i3cdev->info.dyn_addr = i3cdev->boardinfo->init_dyn_addr;
> > +	ret = i3c_master_reattach_i3c_dev(i3cdev, 0);
> >  	if (ret)
> >  		goto err_rstdaa;
> >  
> > -	ret = i3c_master_retrieve_dev_info(dev);
> > +	ret = i3c_master_retrieve_dev_info(i3cdev);
> >  	if (ret)
> >  		goto err_rstdaa;
> >  
> > -	return;
> > +	return 0;
> >  
> >  err_rstdaa:
> > -	i3c_master_rstdaa_locked(master, dev->boardinfo->init_dyn_addr);
> > +	i3c_master_rstdaa_locked(master, i3cdev->boardinfo->init_dyn_addr);
> > +err_setdasa:

Let's be consistent with the rest of the framework. Labels don't encode
what the error is but what's expected to be undone. IOW, this one
should be err_detach_dev

> > +	i3c_master_detach_i3c_dev(i3cdev);
> > +err_attach:

and this one err_free_dev.

> > +	i3c_master_free_i3c_dev(i3cdev);
> > +
> > +	return ret;
> >  }
> >  
> >  static void
> > @@ -1619,8 +1637,8 @@ static void i3c_master_detach_free_devs(struct i3c_master_controller *master)
> >   * This function is following all initialisation steps described in the I3C
> >   * specification:
> >   *
> > - * 1. Attach I2C and statically defined I3C devs to the master so that the
> > - *    master can fill its internal device table appropriately
> > + * 1. Attach I2C devs to the master so that the master can fill its internal
> > + *    device table appropriately
> >   *
> >   * 2. Call &i3c_master_controller_ops->bus_init() method to initialize
> >   *    the master controller. That's usually where the bus mode is selected
> > @@ -1633,10 +1651,14 @@ static void i3c_master_detach_free_devs(struct i3c_master_controller *master)
> >   * 4. Disable all slave events.
> >   *
> >   * 5. Pre-assign dynamic addresses requested by the FW with SETDASA for I3C
> > - *    devices that have a static address
> > + *    devices that have a static address and attach corresponding statically
> > + *    defined I3C devices to the master. If only init_dyn_addr is available
> > + *    or if SETDASA fails, reserve those init_dyn_addr to be used later to set
> > + *    address using SETNEWDA after DAA.

I'd re-order this to match what really happens: first reserve slots for
devices that have an init_dyn_addr defined, then try to create+attach
devices that also have a static address defined.

> >   *
> >   * 6. Do a DAA (Dynamic Address Assignment) to assign dynamic addresses to all
> > - *    remaining I3C devices
> > + *    remaining I3C devices and attach them to the master if the dynamic address
> > + *    assignment succeeds

Can we move that change to a separate patch?

> >   *
> >   * Once this is done, all I3C and I2C devices should be usable.
> >   *
> > @@ -1647,7 +1669,6 @@ 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 i2c_dev_desc *i2cdev;
> >  	int ret;
> >  
> > @@ -1679,34 +1700,6 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
> >  			goto err_detach_devs;
> >  		}
> >  	}
> > -	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;
> > -		}
> > -	}
> >  
> >  	/*
> >  	 * Now execute the controller specific ->bus_init() routine, which
> > @@ -1744,10 +1737,33 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
> >  
> >  	/*
> >  	 * Pre-assign dynamic address and retrieve device information if
> > -	 * needed.
> > +	 * needed. And reserve the init_dyn_addr in case of failure, to retry
> > +	 * setting the requested address after DAA is done in
> > +	 * i3c_master_add_i3c_dev_locked().

That's no longer accurate: init_dyn_addr are reserved up-front and
device creation is only attempted if the device has a static address.

> >  	 */
> > -	i3c_bus_for_each_i3cdev(&master->bus, i3cdev)
> > -		i3c_master_pre_assign_dyn_addr(i3cdev);
> > +	list_for_each_entry(i3cboardinfo, &master->boardinfo.i3c, node) {
> > +		/*
> > +		 * We don't attach devices which are not addressable
> > +		 * (no static_addr and dyn_addr) and devices with static_addr
> > +		 * but no init_dyn_addr will participate in DAA.
> > +		 */  
> 
> The above comment should be split:
> 
> 		/*
> 		 * We don't reserve a dynamic address for devices that
> 		 * don't explicitly request one.
> 		 */
> 
> > +		if (!i3cboardinfo->init_dyn_addr)
> > +			continue;
> > +
> > +		ret = i3c_bus_get_addr_slot_status(&master->bus,
> > +						   i3cboardinfo->init_dyn_addr);
> > +		if (ret != I3C_ADDR_SLOT_FREE) {
> > +			ret = -EBUSY;
> > +			goto err_rstdaa;
> > +		}
> > +
> > +		i3c_bus_set_addr_slot_status(&master->bus,
> > +					     i3cboardinfo->init_dyn_addr,
> > +					     I3C_ADDR_SLOT_I3C_DEV);
> > +  
> 		/*
> 		 * Only try to create/attach devices that have a static
> 		 * address. Other devices will be created/attached when
> 		 * DAA happens, and the requested dynamic address will
> 		 * be set using SETNEWDA once those devices become
> 		 * addressable.
> 		 */
> > +		if (i3cboardinfo->static_addr)
> > +			i3c_master_early_i3c_dev_add(master, i3cboardinfo);
> > +	}
> >  
> >  	ret = i3c_master_do_daa(master);
> >  	if (ret)  
> 

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