linux-kernel - Re: [Intel-gfx] [PATCH 6/7] drm/i915: Disable FDI RX before FDI TX

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Message-ID: <CAPX-8+_bZNyXL0b8nBkN97sj-KnT_eZXZ-5Hp5R6P-L-D-QAKg@mail.gmail.com>
Date:	Fri, 17 Aug 2012 17:43:22 +0100
From:	"Lespiau, Damien" <damien.lespiau@...el.com>
To:	Keith Packard <keithp@...thp.com>
Cc:	intel-gfx@...ts.freedesktop.org,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 6/7] drm/i915: Disable FDI RX before FDI TX

On Tue, Aug 14, 2012 at 5:34 AM, Keith Packard <keithp@...thp.com> wrote:
> Doesn't make sense to disable in the other order.
>
> Signed-off-by: Keith Packard <keithp@...thp.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

I can't see anything in the docs about an order requirement for those.
Not sure why the other way does not make sense. Somehow disabling TX
before RX makes some sense to me (TX enabled without a ready RX looks
weird?, no data should flow as the pipe is shutdown at that point
anyway). Maybe it just does not matter?

Another detail is that disabling the PLLs seem to have an order in the
disabling sequence, TX, then RX.

I.  Disable CPU FDI Transmitter PLL
II. Disable PCH FDI Receiver PLL

-- 
Damien
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