From: Chris Wilson <chris@chris-wilson.co.uk>
To: Ben Widawsky <ben@bwidawsk.net>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: Wait for the clocks to stabilise before updating PLLs
Date: Wed, 02 May 2012 21:26:36 +0100 [thread overview]
Message-ID: <1335990397_122527@CP5-2952> (raw)
In-Reply-To: <20120502131459.0fdbb7b5@bwidawsk.net>
On Wed, 2 May 2012 13:14:59 -0700, Ben Widawsky <ben@bwidawsk.net> wrote:
> On Wed, 2 May 2012 20:43:56 +0100
> Chris Wilson <chris@chris-wilson.co.uk> wrote:
When initialising the PLL registers we may have to clear existing state
from the BIOS - that is the PLL may already be enabled. So we need to
disable it, wait for the clocks to settle and then rewrite it.
The issue came to light when Ben tested
commit 88ca4bb7974277793e602d88739d4e8f56b89e64
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date: Fri Apr 20 17:11:53 2012 +0100
drm/i915: manage PCH PLLs separately from pipes
and found that booting into a VGA monitor was no longer working. Closer
inspection suggests that it was a pre-existing bug now being hit by the
rearranged code. Perhaps Ben was not even the first person to stumble
upon this bug, https://bugs.freedesktop.org/show_bug.cgi?id=37029.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Ben Widawsky <ben@bwidawsk.net>
> > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> Reported-and-tested-by: Ben Widawsky <ben@bwidawsk.net>
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
next prev parent reply other threads:[~2012-05-02 20:26 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-02 19:43 [PATCH] drm/i915: Wait for the clocks to stabilise before updating PLLs Chris Wilson
2012-05-02 20:14 ` Ben Widawsky
2012-05-02 20:26 ` Chris Wilson [this message]
2012-05-03 9:13 ` Daniel Vetter
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