From: Adam Jackson <ajax@redhat.com>
To: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: always set FDI composite sync bit
Date: Tue, 11 Oct 2011 12:42:22 -0400 [thread overview]
Message-ID: <4E9471EE.9080201@redhat.com> (raw)
In-Reply-To: <20111011091649.784c9545@jbarnes-desktop>
On 10/11/11 12:16 PM, Jesse Barnes wrote:
> On Tue, 11 Oct 2011 10:10:24 -0400 Adam Jackson<ajax@redhat.com> wrote:
>> It still seems entirely magical and probably wrong in some situations.
>> And I'm thrilled to see that PPT is functionally different from CPT
>> (seriously, stop doing that) instead of just moving bit definitions
>> around (seriously, stop doing that). But this change is massively
>> better than before.
>
> Without composite sync, FDI needs frame/line sync (the fsync/lsync
> mentioned in the docs), which means extra wires between the CPU and
> PCH. Some boards don't have these and so we need to use composite.
> For the same reason, if FDI B and C are sharing lanes, we need to use
> composite or we won't have enough lines to go around.
>
> I've asked the hardware guys whether using composite on a board that
> supports fsync/lsync is ok generally; if so just defaulting to that
> everywhere should be fine.
Makes sense. If true this seems worth doing for CPT too. The IBX docs
don't make any mention of composite sync.
- ajax
next prev parent reply other threads:[~2011-10-11 17:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-10 21:28 [PATCH] drm/i915: always set FDI composite sync bit Jesse Barnes
2011-10-10 21:53 ` Adam Jackson
2011-10-10 22:49 ` Eugeni Dodonov
2011-10-10 23:22 ` Keith Packard
2011-10-11 14:10 ` Adam Jackson
2011-10-11 16:16 ` Jesse Barnes
2011-10-11 16:42 ` Adam Jackson [this message]
2011-10-11 17:38 ` Jesse Barnes
2011-10-11 16:40 ` Jesse Barnes
2011-10-11 17:26 ` Keith Packard
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