linux-kernel - Re: [PATCH v3 03/11] i3c: master: Extend address status bit to 4 and add I3C_ADDR_SLOT_EXT

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Message-ID: <20240823180426.056ac093@xps-13>
Date: Fri, 23 Aug 2024 18:04:26 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Frank Li <Frank.Li@....com>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>, Boris Brezillon
 <boris.brezillon@...labora.com>, Parshuram Thombare <pthombar@...ence.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Boris Brezillon
 <bbrezillon@...nel.org>, Arnd Bergmann <arnd@...db.de>, Conor Culhane
 <conor.culhane@...vaco.com>, linux-i3c@...ts.infradead.org,
 linux-kernel@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [PATCH v3 03/11] i3c: master: Extend address status bit to 4
 and add I3C_ADDR_SLOT_EXT_INIT

Hi Frank,


>  static bool i3c_bus_dev_addr_is_avail(struct i3c_bus *bus, u8 addr)
>  {
>  	enum i3c_addr_slot_status status;
> @@ -388,6 +405,14 @@ static int i3c_bus_get_free_addr(struct i3c_bus *bus, u8 start_addr)
>  	enum i3c_addr_slot_status status;
>  	u8 addr;
>  
> +	/* try find an address, which have not pre-allocated by assigned-address */

	Try	to find			has   been

pre-allocated?

> +	for (addr = start_addr; addr < I3C_MAX_ADDR; addr++) {
> +		status = i3c_bus_get_addr_slot_status_ext(bus, addr);
> +		if (status == I3C_ADDR_SLOT_FREE)
> +			return addr;
> +	}
> +
> +	/* use pre-allocoated by assigned-address because such device was removed at bus*/

	  Use      allocated 

pre-allocated or assigned?

I guess the logic should be:
- try the assigned-address
- look for a free slot
- look for an already in use slot that must concern a disconnected
  device

But the comments are not precise enough IMHO. Can you rephrase them?

>  	for (addr = start_addr; addr < I3C_MAX_ADDR; addr++) {
>  		status = i3c_bus_get_addr_slot_status(bus, addr);
>  		if (status == I3C_ADDR_SLOT_FREE)
> @@ -1906,9 +1931,9 @@ static int i3c_master_bus_init(struct i3c_master_controller *master)
>  			goto err_rstdaa;
>  		}
>  
> -		i3c_bus_set_addr_slot_status(&master->bus,
> -					     i3cboardinfo->init_dyn_addr,
> -					     I3C_ADDR_SLOT_I3C_DEV);
> +		i3c_bus_set_addr_slot_status_ext(&master->bus,
> +						 i3cboardinfo->init_dyn_addr,
> +						 I3C_ADDR_SLOT_I3C_DEV | I3C_ADDR_SLOT_EXT_INIT);
>  
>  		/*
>  		 * Only try to create/attach devices that have a static
> diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
> index 4601b6957f799..c923b76bbc321 100644
> --- a/include/linux/i3c/master.h
> +++ b/include/linux/i3c/master.h
> @@ -284,6 +284,8 @@ enum i3c_bus_mode {
>   * @I3C_ADDR_SLOT_I2C_DEV: address is assigned to an I2C device
>   * @I3C_ADDR_SLOT_I3C_DEV: address is assigned to an I3C device
>   * @I3C_ADDR_SLOT_STATUS_MASK: address slot mask
> + * @I3C_ADDR_SLOT_EXT_INIT: the bit mask display of addresses is preferred by some devices,

I'm sorry, but I don't understand what "bit mask display of addresses"
means.

> + *			    such as the "assigned-address" in device tree source (dts).
>   *
>   * On an I3C bus, addresses are assigned dynamically, and we need to know which
>   * addresses are free to use and which ones are already assigned.
> @@ -297,9 +299,11 @@ enum i3c_addr_slot_status {
>  	I3C_ADDR_SLOT_I2C_DEV,
>  	I3C_ADDR_SLOT_I3C_DEV,
>  	I3C_ADDR_SLOT_STATUS_MASK = 3,
> +	I3C_ADDR_SLOT_EXT_STATUS_MASK = 7,
> +	I3C_ADDR_SLOT_EXT_INIT = BIT(2),
>  };
>  
> -#define I3C_ADDR_SLOT_BITS 2
> +#define I3C_ADDR_SLOT_BITS 4
>  
>  /**
>   * struct i3c_bus - I3C bus object
> 


Thanks,
Miquèl