[Intel-gfx] [PATCH] drm/i915: add missing "break"
przanoni at gmail.com
Fri Sep 23 05:06:31 PDT 2011
2011/9/23 Keith Packard <keithp at keithp.com>:
> On Fri, 23 Sep 2011 08:13:15 +0530, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
>> What I don't understand about the refclk code is that we should be able
>> to leave everything enabled and just select the right clock source in
>> the DPLL_SEL bits. But that doesn't seem to help the wavy VGA bug,
>> since in that case I think we're explicitly choosing the non-SSC clock
>> and we still get waviness.
> We don't have any hardware anywhere which exhibits this problem, do we?
> Getting hold of some would let us poke at it.
My personal laptop reproduces the "wavy output" problem.
If you look at the patch posted on comment #20 of bug #38750 ,
you'll see that it checks on the video bios for a field called
"display_clock_mode" and then uses this field in the following code:
+ if (dev_priv->display_clock_mode)
+ temp |= DREF_NONSPREAD_CK505_ENABLE;
+ temp |= DREF_NONSPREAD_SOURCE_ENABLE;
This is what fixes the wavy output problem: setting
DREF_NONSPREAD_CK505_ENABLE instead of the other bits.
And for Keith's patch:
Tested-By: Paulo Zanoni <paulo.r.zanoni at intel.com>
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