From: Adam Jackson <ajax@redhat.com>
To: Keith Packard <keithp@keithp.com>
Cc: "drivers, Intel" <Intel-gfx@lists.freedesktop.org>
Subject: Re: Flicker-free boot in DRM
Date: Mon, 31 Oct 2011 12:56:58 -0400 [thread overview]
Message-ID: <4EAED35A.4040307@redhat.com> (raw)
In-Reply-To: <yunk47n2jjv.fsf@aiko.keithp.com>
On 10/30/11 12:24 AM, Keith Packard wrote:
> On Sat, 29 Oct 2011 00:05:22 -0700, "Keith Packard"<keithp@keithp.com> wrote:
>
>> * I've got LVDS pulling the current mode out of the hardware
>
> With a machine that has a native VBE mode for the panel, the problem is
> that clock computed from the hardware settings is not quite the same as
> the clock requested in the mode. I think the clock computation must be
> slightly off, but even with that fixed, it will probably not quite
> match. I think we'll need a magic flag in this mode telling DRM to allow
> a bit of fuzz in clock matching.
Yeah, it won't be precise. That's why there's PLL search code at all,
and why it has a fuzz factor for finding "good enough".
I ran the math for the maximum error in the PLL search back when I was
fixing a case where it fell through and failed to find timings at all.
See 6ba770dc5c334aff1c055c8728d34656e0f091e2.
- ajax
next prev parent reply other threads:[~2011-10-31 17:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-29 7:05 Flicker-free boot in DRM Keith Packard
2011-10-29 8:12 ` Chris Wilson
2011-10-29 21:54 ` Keith Packard
2011-10-30 4:24 ` Keith Packard
2011-10-31 16:56 ` Adam Jackson [this message]
2011-10-31 18:43 ` Keith Packard
2011-10-31 18:59 ` Adam Jackson
2011-10-31 16:57 ` Jesse Barnes
2011-10-31 18:45 ` Keith Packard
2011-10-31 17:00 ` Adam Jackson
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