linux-kernel - Re: [PATCH RFC] media: rc: OF: Add Generic bindings for remote-control

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Message-ID: <524C482E.3050003@st.com>
Date:	Wed, 02 Oct 2013 17:22:06 +0100
From:	Srinivas KANDAGATLA <srinivas.kandagatla@...com>
To:	Mauro Carvalho Chehab <m.chehab@...sung.com>
Cc:	Mark Rutland <mark.rutland@....com>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	Pawel Moll <Pawel.Moll@....com>,
	Stephen Warren <swarren@...dotorg.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Landley <rob@...dley.net>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] media: rc: OF: Add Generic bindings for remote-control

On 01/10/13 15:49, Mauro Carvalho Chehab wrote:
>>> > > 
>>> > > Btw, we're even thinking on mapping HDMI-CEC remote controller RX/TX via
>>> > > the RC subsystem. So, another L1 protocol would be "hdmi-cec".
>>> > > 
>> > Ok.
>>> > > Yet, it seems unlikely that the very same remote controller IP would use
>>> > > a different protocol for RX and TX, while sharing the same registers.
>> > 
>> > ST IRB block has one IR processor which has both TX and RX support and
>> > one UHF Processor which has RX support only. However the register map
>> > for all these support is in single IRB IP block.
>> > 
>> > So the driver can configure the IP as TX in "infrared" and RX in "uhf".
>> > This is supported in ST IRB IP.
>> > 
>> > This case can not be represented in a single device tree node with
>> > l1-protocol and direction properties.
>> > 
>> > IMHO, having tx-mode and rx-mode or tx-protocol and rx-protocol
>> > properties will give more flexibility.
>> > 
>> > What do you think?
> Yeah, if they're using the same registers, then your proposal works
> better.
> 
> I would prefer to not call it as just protocol, as IR has an
> upper layer protocol that defines how the bits are encoded, e. g.
> RC5, RC6, NEC, SONY, ..., with is what we generally call as protocol
> on rc-core. 
> 
> A proper naming for it is hard to find. Well, for IR/UHF, it is actually

Yes I agree.

> specifying the medium, but for Bluetooth, HDMI-CEC, it defines a
> protocol stack to be used, with covers not only the physical layer of
> the OSI model.
> 
> Perhaps the better would be to call it as: tx-proto-stack/rx-proto-stack.
> 
How are we going to address use case highlighted by Mark R, like N
Connections on a single IP block?

This use-case can not be addressed with tx-mode and rx-mode or
tx-proto-stack/rx-proto-stack properties.

So the idea of generic properties for tx and rx sounds incorrect.

IMHO, Best thing would be to drop the idea of using tx-mode and rx-mode
as generic properties and use "st,tx-mode" and "st,rx-mode" instead for
st-rc driver.

What do you think?

Thanks,
srini


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