linux-kernel - Re: [PATCH v2 20/28] drm/i2c: tda998x: move the TBG_CNTRL

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Message-ID: <20140112123159.GS15937@n2100.arm.linux.org.uk>
Date:	Sun, 12 Jan 2014 12:31:59 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Jean-Francois Moine <moinejf@...e.fr>
Cc:	dri-devel@...ts.freedesktop.org, Rob Clark <robdclark@...il.com>,
	Dave Airlie <airlied@...il.com>, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 20/28] drm/i2c: tda998x: move the TBG_CNTRL_0
	register setting

On Sun, Jan 12, 2014 at 01:23:21PM +0100, Jean-Francois Moine wrote:
> On Sat, 11 Jan 2014 18:36:48 +0000
> Russell King - ARM Linux <linux@....linux.org.uk> wrote:
> 
> > On Thu, Jan 09, 2014 at 12:06:07PM +0100, Jean-Francois Moine wrote:
> > > According to the comment, the TBG_CNTRL_0 register must be set at the
> > > end of the mode change sequence.
> > 
> > So you believe comments without understanding the history, and you move
> > code around due to those.
> > 
> > No, this is again wrong.  That write to REG_TBG_CNTRL_0 in the sequence
> > writing the video information to the chip.  This doesn't encompass the
> > HDMI/DVI mode setting nor the audio configuration - the audio configuration
> > can change independently of the video setting, and does not require this
> > register to be written.
> > 
> > This also brings up a bug in one of your previous patches which I now
> > must go back and comment upon.
> 
> Well, I have not the full spec of the TDA998x's, and I don't know what
> is important or not. I was hoping that Rob had a better knowledge than I.
> 
> So, in my patch 9, I was writing the REG_TBG_CNTRL_1 after writing
> REG_TBG_CNTRL_0, and you refused it. Here, I write REG_TBG_CNTRL_0
> after the write of REG_TBG_CNTRL_1 in the HDMI sequence, and you still
> don't agree.
> 
> What is the right way?

No, both NAKS are for the exact same issue.

Patch 9 inserted the write to REG_TBG_CNTRL_1 after REG_TBG_CNTRL_0.
Then in this patch you move REG_TBG_CNTRL_0 after all writes.

Had you appropriately placed the write to REG_TBG_CNTRL_1 in patch 9
in the first place, _this_ patch (patch 20) would not be required to
then move REG_TBG_CNTRL_0 after it.  So, fixing patch 9 removes the
need for patch 20.

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