Re: [Intel-gfx] [PATCH 3/7] drm/i915: Treat PCH eDP like DP in mostplaces

From: Adam Jackson
Date: Wed Nov 02 2011 - 16:36:00 EST


On 11/2/11 4:05 PM, Keith Packard wrote:
On Wed, 02 Nov 2011 15:36:20 -0400, Adam Jackson<ajax@xxxxxxxxxx> wrote:

The VBT is going to be crap.

The only question then is what to do with hardware that doesn't have the
DPCD value -- that's "new" in revision 0x11, after all.

It is? The DP 1.1a text for lane count is "For Rev.1.1, only the following three values are supported. All other values are reserved." I don't think that implies anything about what it meant in 1.0. It does say that bits 7:5 of that register are reserved in 1.0 though; since it doesn't have any versioning on bits 4:0 I'd think that means they're interpreted the same in 1.0 as in 1.1.

Unless you have a copy of the 1.0 spec?

Again, not that it probably matters much. I think the installed base of DP 1.0 sinks is zero, I've literally never seen one.

How about this:

commit 34ebe02cc78f20ae6b7865c5087c3b5ac7810185
Author: Keith Packard<keithp@xxxxxxxxxx>
Date: Wed Nov 2 13:03:47 2011 -0700

drm/i915: Use DPCD value for max DP lanes where possible

Fall back to the VBT value for eDP monitors only when DPCD is missing
the value.

Signed-off-by: Keith Packard<keithp@xxxxxxxxxx>

Reviewed-by: Adam Jackson <ajax@xxxxxxxxxx>

- ajax
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