Re: [Intel-gfx] [PATCH 6/7] drm/i915: Disable FDI RX before FDI TX
From: Keith Packard
Date: Fri Aug 17 2012 - 19:10:42 EST
"Lespiau, Damien" <damien.lespiau@xxxxxxxxx> writes:
> I can't see anything in the docs about an order requirement for those.
Right, the docs don't say anything, which is a bit disconcerting.
> 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?
And here I figured disabling RX before TX made more sense -- otherwise
the receiver wouldn't be seeing anything. In other areas of the driver,
we're careful to disable receivers before senders (disable CRTC before
PLL, etc).
> 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
That ordering doesn't matter as the FDI receiver and transmitter are
both disabled by that point, so they aren't talking at all.
--
keith.packard@xxxxxxxxx
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