linux-kernel - Re: [PATCH 0/3] omapdss: venc: Add support for bypass and acbias.

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Date:	Mon, 11 Nov 2013 14:57:30 +0100
From:	"Dr. H. Nikolaus Schaller" <hns@...delico.com>
To:	Tomi Valkeinen <tomi.valkeinen@...com>
Cc:	Belisko Marek <marek.belisko@...il.com>,
	Tony Lindgren <tony@...mide.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	<linux-fbdev@...r.kernel.org>, NeilBrown <neilb@...e.de>,
	Marek Belisko <marek@...delico.com>
Subject: Re: [PATCH 0/3] omapdss: venc: Add support for bypass and acbias.

Hi Tomi,

Am 11.11.2013 um 14:29 schrieb Tomi Valkeinen:

> Hi,
> 
> On 2013-11-05 09:24, Belisko Marek wrote:
>> Hi,
>> 
>> ping.
>> 
>> On Mon, Oct 14, 2013 at 11:02 PM, Marek Belisko <marek@...delico.com> wrote:
>>> This patches is adding bypass and acbias functionality to omapdss venc driver.
>>> In first patch we export updatin bypass and acbias in devconf1 register. Next patch
>>> add handling for updating in venc driver and last patch add driver for opa362 which
>>> is used on gta04 board and set bypass + acbias.
>> Is there a chance to get this series to 3.13? Thanks.
> 
> Sorry, I haven't had time to do much reviewing.
> 
> The code in omap3-tvout.c should be included in the display.c file,
> which already contains some things like muxing.

Ok, that might be better - but we were not sure where to place code to
modify the DEVCONF1 registers. It is not directly DSS related but a special
control of the OMAP3 SoC. Therefore we think it is better located in omap3-tvout.c

> Also, func(bool, bool)
> style functions are rather confusing to read. Maybe an enum would be
> better, so you'd instead have something like:
> 
> func(OMAP_VENC_TVOUTBYPASS | OMAP_VENC_TVACEN)

We have no special preference on that.

> 
> But the main issue is: while this series probably works well, I really
> don't like it that the OPA driver needs to pass bypass and acbias. It
> shouldn't know anything about such things. I'm just not certain how to
> implement that with the current omapdss driver.

Well, it must know bypass and acbias because it requires the OMAP
CPU to be configured accordingly. I.e. it is the one who pushes the
button. Or we get a problem that people might misconfigure it.

I would see it similar as a driver must be able to control power. Here
it must be able to control bypass and acbias in a special way that it works.

> I'll try to find time to think about this more, but I don't think I can
> merge this for 3.13.

Please take your time.

And please also consider the approach to merge it into 3.13 as it is
and we can then fix it in the weeks while release candidates are pushed.

But that is your decision.

BR and thanks,
Nikolaus

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