linux-kernel - Re: [PATCH v7 0/7] i2c-atr and FPDLink

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Message-ID: <Y8q6ggmOsygyVdTT@smile.fi.intel.com>
Date:   Fri, 20 Jan 2023 18:00:02 +0200
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Luca Ceresoli <luca.ceresoli@...tlin.com>
Cc:     Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Wolfram Sang <wsa@...nel.org>,
        Matti Vaittinen <Matti.Vaittinen@...rohmeurope.com>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Peter Rosin <peda@...ntia.se>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Michael Tretter <m.tretter@...gutronix.de>,
        Shawn Tu <shawnx.tu@...el.com>,
        Hans Verkuil <hverkuil@...all.nl>,
        Mike Pagano <mpagano@...too.org>,
        Krzysztof Hałasa <khalasa@...p.pl>,
        Marek Vasut <marex@...x.de>
Subject: Re: [PATCH v7 0/7] i2c-atr and FPDLink

On Thu, Jan 19, 2023 at 09:43:58AM +0100, Luca Ceresoli wrote:
> On Wed, 18 Jan 2023 19:43:23 +0200
> Andy Shevchenko <andriy.shevchenko@...el.com> wrote:
> > On Wed, Jan 18, 2023 at 07:28:20PM +0200, Tomi Valkeinen wrote:
> > > On 18/01/2023 18:01, Andy Shevchenko wrote:  
> > > > On Wed, Jan 18, 2023 at 02:40:24PM +0200, Tomi Valkeinen wrote:  

...

> > > Can you clarify what you mean here?
> > > 
> > > The i2c_clients are not aware of the i2c-atr. They are normal i2c clients.
> > > The FPD-Link drivers are aware of the ATR, as the FPD-Link hardware contains
> > > the ATR support.  
> > 
> > Can't that hardware be represented as I2C adapter? In such case the ATR specifics
> > can be hidden from the client (drivers).
> > 
> > I'm worrying about code duplication and other things that leak into drivers as
> > ATR callbacks.
> 
> Which callbacks do you refer to? i2c_atr_ops? I don't think we can do
> without the attach/detach_client ones, it's where the driver-specific
> implementation is hooked for the generic ATR infra to call it.
> 
> However now I noticed the select/deselect ops are still there. IIRC
> they are not used by any driver and in the past the plan was to just
> remove them. Tomi, do you think there is a good reason to keep them?
> 
> > It might be that I didn't get how hw exactly functioning on this
> > level and why we need those callbacks.
> 
> As far as "how hw exactly works", in case you haven't seen that, the
> best explanation I was able to give is in my ELCE 2019 talk, at minute
> ~22. It's a 2-3 minute watch. The slides have pointers to other talks
> and discussion.

Probably I have missed the URL in the discussion, care to resend?

-- 
With Best Regards,
Andy Shevchenko