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From: Wolfram Sang <wsa@the-dreams.de>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>,
	linux-media@vger.kernel.org,
	"open list:OPEN FIRMWARE AND..." <devicetree@vger.kernel.org>,
	Jacopo Mondi <jacopo+renesas@jmondi.org>,
	Hans Verkuil <hans.verkuil@cisco.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Mauro Carvalho Chehab <mchehab@s-opensource.com>
Subject: Re: [PATCH v3 02/11] media: ov772x: allow i2c controllers without I2C_FUNC_PROTOCOL_MANGLING
Date: Mon, 23 Apr 2018 22:36:16 +0200	[thread overview]
Message-ID: <20180423203615.2ntymbibkgw2aiks@ninjato> (raw)
In-Reply-To: <6809346.dy34v3ukH6@avalon>

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> SCCB helpers would work too. It would be easy to just move the functions 
> defined in this patch to helpers and be done with it. However, there are I2C 
> adapters that have native SCCB support, so to take advantage of that feature 

Ah, didn't notice that so far. Can't find it in drivers/i2c/busses.
Where are those?

> we need to forward native SCCB calls all the way down the stack in that case. 

And how is it done currently?

> That's why I thought an implementation in the I2C subsystem would be better. 
> Furthermore, as SCCB is really a slightly mangled version of I2C, I think the 
> I2C subsystem would be a natural location for the implementation. It shouldn't 

Can be argued. But it can also be argues that it sits on top of I2C and
doesn't need to live in i2c-folders itself (like PMBus). The
implementation given in this patch looks a bit like the latter. However,
this is not the main question currently.

> be too much work, it's just a matter of deciding what the call stacks should 
> be for the native vs. emulated cases.

I don't like it. We shouldn't use SMBus calls for SCCB because SMBus
will very likely never support it. Or do you know of such a case? I
think I really want sccb helpers. So, people immediately see that SCCB
is used and not SMBus or I2C. And there, we can handle native support
vs. I2C-SCCB-emulation. And maybe SMBus-SCCB emulation but I doubt we
will ever need it.


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  reply	other threads:[~2018-04-23 20:36 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-22 15:56 [PATCH v3 00/11] media: ov772x: support media controller, device tree probing, etc Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 01/11] media: dt-bindings: ov772x: add device tree binding Akinobu Mita
2018-04-23  9:17   ` Laurent Pinchart
2018-04-23 15:54     ` Akinobu Mita
2018-04-25 16:19       ` Akinobu Mita
2018-04-25 22:40         ` Laurent Pinchart
2018-04-26 16:17           ` Akinobu Mita
2018-04-26 18:11             ` jacopo mondi
2018-04-26 21:34             ` Laurent Pinchart
2018-04-27 17:15               ` Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 02/11] media: ov772x: allow i2c controllers without I2C_FUNC_PROTOCOL_MANGLING Akinobu Mita
2018-04-23  9:18   ` Laurent Pinchart
2018-04-23 15:55     ` Akinobu Mita
2018-04-23 19:41       ` Laurent Pinchart
2018-04-23 20:11         ` Wolfram Sang
2018-04-23 20:21           ` Laurent Pinchart
2018-04-23 20:36             ` Wolfram Sang [this message]
2018-04-23 20:51               ` Laurent Pinchart
2018-04-24 10:04                 ` Sakari Ailus
2018-04-26 12:32                 ` Wolfram Sang
2018-04-22 15:56 ` [PATCH v3 03/11] media: ov772x: add checks for register read errors Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 04/11] media: ov772x: add media controller support Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 05/11] media: ov772x: use generic names for reset and powerdown gpios Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 06/11] media: ov772x: support device tree probing Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 07/11] media: ov772x: handle nested s_power() calls Akinobu Mita
2018-04-23  8:35   ` jacopo mondi
2018-04-27 17:20     ` Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 08/11] media: ov772x: reconstruct s_frame_interval() Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 09/11] media: ov772x: avoid accessing registers under power saving mode Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 10/11] media: ov772x: make set_fmt() return -EBUSY while streaming Akinobu Mita
2018-04-22 15:56 ` [PATCH v3 11/11] media: ov772x: create subdevice device node Akinobu Mita

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