linux-kernel - Re: [PATCH v6 01/10] i3c: Add core I3C infrastructure

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Date:   Fri, 24 Aug 2018 18:52:52 +0100
From:   vitor <Vitor.Soares@...opsys.com>
To:     Boris Brezillon <boris.brezillon@...tlin.com>,
        vitor <Vitor.Soares@...opsys.com>, <linux-gpio@...r.kernel.org>,
        Sekhar Nori <nsekhar@...com>
CC:     Wolfram Sang <wsa@...-dreams.de>, <linux-i2c@...r.kernel.org>,
        "Jonathan Corbet" <corbet@....net>, <linux-doc@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Przemyslaw Sroka <psroka@...ence.com>,
        Arkadiusz Golec <agolec@...ence.com>,
        Alan Douglas <adouglas@...ence.com>,
        Bartosz Folta <bfolta@...ence.com>,
        Damian Kos <dkos@...ence.com>,
        Alicja Jurasik-Urbaniak <alicja@...ence.com>,
        "Cyprian Wronka" <cwronka@...ence.com>,
        Suresh Punnoose <sureshp@...ence.com>,
        "Rafal Ciepiela" <rafalc@...ence.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Nishanth Menon <nm@...com>, Rob Herring <robh+dt@...nel.org>,
        Pawel Moll <pawel.moll@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ian Campbell <ijc+devicetree@...lion.org.uk>,
        "Kumar Gala" <galak@...eaurora.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Xiang Lin <Xiang.Lin@...aptics.com>,
        Przemyslaw Gaj <pgaj@...ence.com>,
        Peter Rosin <peda@...ntia.se>
Subject: Re: [PATCH v6 01/10] i3c: Add core I3C infrastructure

Hi Boris,


On 24-08-2018 13:39, Boris Brezillon wrote:
> Hi Vitor,
>
> On Wed, 22 Aug 2018 17:43:34 +0100
> vitor <Vitor.Soares@...opsys.com> wrote:
>
>> Hi Boris,
>>
>>
>> On 19-07-2018 16:29, Boris Brezillon wrote:
>>> +int i3c_bus_register(struct i3c_bus *i3cbus)
>>> +{
>>> +	struct i2c_dev_desc *desc;
>>> +
>>> +	i3c_bus_for_each_i2cdev(i3cbus, desc) {
>>> +		switch (desc->boardinfo->lvr & I3C_LVR_I2C_INDEX_MASK) {
>>> +		case I3C_LVR_I2C_INDEX(0):
>>> +			if (i3cbus->mode < I3C_BUS_MODE_MIXED_FAST)
>>> +				i3cbus->mode = I3C_BUS_MODE_MIXED_FAST;
>>> +			break;
>>> +
>>> +		case I3C_LVR_I2C_INDEX(1):
>>> +		case I3C_LVR_I2C_INDEX(2):
>>> +			if (i3cbus->mode < I3C_BUS_MODE_MIXED_SLOW)
>>> +				i3cbus->mode = I3C_BUS_MODE_MIXED_SLOW;
>>> +			break;
>>> +
>>> +		default:
>>> +			return -EINVAL;
>>> +		}
>>> +	}
>>> +
>>> +	if (!i3cbus->scl_rate.i3c)
>>> +		i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
>>> +
>>> +	if (!i3cbus->scl_rate.i2c) {
>>> +		if (i3cbus->mode == I3C_BUS_MODE_MIXED_SLOW)
>>> +			i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_SCL_RATE;
>>> +		else
>>> +			i3cbus->scl_rate.i2c = I3C_BUS_I2C_FM_PLUS_SCL_RATE;
>>> +	}
>>> +
>>> +	/*
>>> +	 * I3C/I2C frequency may have been overridden, check that user-provided
>>> +	 * values are not exceeding max possible frequency.
>>> +	 */
>>> +	if (i3cbus->scl_rate.i3c > I3C_BUS_MAX_I3C_SCL_RATE ||
>>> +	    i3cbus->scl_rate.i2c > I3C_BUS_I2C_FM_PLUS_SCL_RATE) {
>>> +		return -EINVAL;
>>> +	}
>>> +
>>> +	dev_set_name(&i3cbus->dev, "i3c-%d", i3cbus->id);
>>> +
>>> +	return device_add(&i3cbus->dev);
>>> +}
>> During the tests of the bus with i2c devices I found the i2c_dev_desc
>> objects aren't allocated before this function. This cause i3cbus->mode =
>> I3C_BUS_MODE_PURE.
> I just checked and DT parsing (+ I2C descs creation) is done before
> i3c_bus_register() is called, so we should be good. How did you declare
> your I2C devices (right now, only DT declaration is supported).
During the DT parsing, you create the i2c_dev_boardinfo. the 
i2c_dev_desc is created in i3c_master_bus_init() which is after the 
i3c_mater_create_bus(). One possible way to fix this is to pass master 
also to i3c_bus_register and iterate over i2c_dev_board_info list.

>> I want to do something for the slave and secondary master, do you
>> already have infrastructure that you can share?
> What do you mean?
>
> Regards,
>
> Boris

I want start to add the secondary master functionality but it is also 
necessary to add the infrastructure to the subsystem.
So, to avoid duplicated work can you share your plans for the secondary 
master?

Best regards,
Vitor Soares