Date:   Tue, 4 Dec 2018 00:34:20 +0000
From:   vitor <vitor.soares@...opsys.com>
To:     Boris Brezillon <boris.brezillon@...tlin.com>,
        vitor <vitor.soares@...opsys.com>
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Subject: Re: [PATCH] i3c: master: dw: split dw-i3c-master.c into master and
 bus specific parts

Hi Boris,


Sorry for the delayed response.


On 27/11/18 12:33, Boris Brezillon wrote:
> Hi Vitor,
>
> On Tue, 27 Nov 2018 11:50:53 +0000
> vitor<vitor.soares@...opsys.com>  wrote:
>
>
>>>> Sorry for that and don't take me wrong... maybe I should rise this
>>>> question early but this only came up now when I started splitting and
>>>> thinking where to put what is for master for slave, what is common and
>>>> the thing of putting everything of controller in a folder.
>>> So you have such a dual-role controller?
>> Yes, we already talked about secondary master support.
> There's a difference between a secondary master that waits for its time
> to become the currrent master, and a secondary master that provides I3C
> device features when it's acting as a slave (sensor, GPIO
> controller, ...). So far we focused on supporting the former. If
> there's a need for the latter, then we should start thinking about the
> slave framework...
>
>>> What I call a slave controller would be something that lets you reply to
>>> SDR/DDR transactions or fill a generic regmap that would be exposed to
>>> other masters on the bus. This way we could implement generic slave
>>> drivers in Linux (the same way we have gadget drivers). Anything else
>>> is likely to be to specific to be exposed as a generic framework.
>> I would bet to do something like in i2c, we don't need the same level of
>> complexity found in USB.
> Can you detail a bit more what you have in mind? I don't think we can
> do like I2C, simply because we need to expose a valid DCR +
> manuf-ID/PID so that other masters can bind the device to the
> appropriate driver on their side. Plus, if we're about to expose
> generic profiles, we likely don't want each I3C slave controller driver
> to do that on its own.


I think this should be discuss in another thread. Do you agree?


>>>> Taking the USB as exemple do you prefer a dwc folder on i3c root?
>>> Hm, not sure I like this idea either. So I see 2 options:
>>>
>>> 1/ put all controller drivers (both master and slave ones) in a common
>>>      directory (drivers/i3c/controllers) as you suggest, and prefix them
>>>      correctly (i3c-master-<ip>.c, i3c-slave-<ip>.c and i3c-dual-<ip>.c)
>> I agree with the controller folder but not with prefix. Please check
>> what is already in the kernel.
> If we mix everything in the same subdir, I'd like to have an easy way
> to quickly identify those that are slave controllers and those that are
> master controllers. For the dual-role thing, maybe we can consider them
> as master (ones with advances slave features).
>
> Would you be okay with drivers/i3c/controllers/{designware,dw}/..., so
> that you can have all designware drivers (for both slave and master
> blocks) in the same dir?


Yes, that was what I trying to tell you. For me this might be the best 
option.

I would like to avoid having dual role i3c driver in a master folder.


> For those that are placed directly under drivers/i3c/controllers/...
> (because they only have one .c file), I'd like to keep a standard
> prefix.


I don't disagree, and for those that have more than one file they should 
be in a folder, right?

What prefix do you have in mind for those files inside a folder?


>> To be clear, the subsystem is nice and I working with daily. As I said
>> this is something that I dealing now and I'm telling what I think that
>> is not correct.
>>
> Come on! All I've seen so far are complaints on tiny details, it
> definitely doesn't prevent you from adding new features.
>
> Regards,
>
> Boris


No, it's not. But as you can see to slipt the driver in parts this 
subject has some relevance.


Best regards,

Vitor Soares

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