From: Thomas Richter <richter@rus.uni-stuttgart.de>
To: intel-gfx@lists.freedesktop.org, Martin@lichtvoll.de
Subject: Re: 3.16, i915: less colors in X?
Date: Sun, 22 Jun 2014 00:51:55 +0200 [thread overview]
Message-ID: <53A60C8B.3090106@rus.uni-stuttgart.de> (raw)
In-Reply-To: <7569_1403385738_53A5F78A_7569_14810_1_2527490.06bevSLs0l@merkaba>
Hi Martin,
>> I'm trying to figure out how to ask X what color depth it is using...?
>
> I think:
>
> martin@merkaba:~> xdpyinfo | grep -i "depth of root"
> depth of root window: 24 planes
>
> but am not completely sure.
>
>> This is thinkpad x60 with Debian 6.0.9.
AFAIK the 830GM chipset does not offer any support for hardware
dithering. Whether the panel in the x60 does I do not know, though.
However, what is remarkable is that graphics on a 16 bit(!) screen may
look more pleasing than graphics on a 24 bit screen, at least for such
ancient machines. The reason is that the panel cuts the bitdepth down
from 8 to 6 bits, without any dithering, just by cutting off the LSBs.
However, if you select a 16bpp mode to begin with, some desktop
environments (specifically gnome) apply a dithering of their own, even
though the output is only 5 bit per component.
This is at least what I see here on the IBM R31 and the Fujitsu S6010:
Gnome desktop at 16bpp looks better than the desktop at 8bpp, due to the
lack of hardware dithering.
The X11 intel driver had an option "Dac6Bit" to signal the 6 bit panel
resolution to X (even though the display pipeline operates in 8 bit
mode), but I have never seen this working in the past time. It seems not
to be supported anymore. Probably that's the culprit.
Martin, you should probably test Ville's alm_fixes5 kernel branch, its
support for the 830GM chipset of the X30 is in my experience much better
than that of the drm-intel-nightly or official kernels.
Greetings,
Thomas
next prev parent reply other threads:[~2014-06-21 22:52 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-13 16:09 3.15-rc: regression in suspend Pavel Machek
2014-05-13 16:19 ` Bjørn Mork
2014-05-13 16:50 ` Pavel Machek
2014-05-13 16:37 ` Pavel Machek
2014-05-13 21:41 ` Pavel Machek
2014-05-14 12:39 ` Jiri Kosina
2014-05-14 15:57 ` Pavel Machek
2014-05-14 16:10 ` Jiri Kosina
2014-05-14 20:31 ` Pavel Machek
2014-05-14 18:20 ` Pavel Machek
2014-05-15 15:29 ` Jiri Kosina
2014-05-15 15:31 ` Daniel Vetter
2014-05-15 15:31 ` Daniel Vetter
2014-06-07 12:05 ` Pavel Machek
2014-06-07 12:06 ` Pavel Machek
2014-06-07 23:11 ` Pavel Machek
2014-06-07 23:11 ` Pavel Machek
2014-06-09 9:25 ` Daniel Vetter
2014-06-09 9:25 ` Daniel Vetter
2014-06-09 10:23 ` Pavel Machek
2014-06-09 10:23 ` Pavel Machek
2014-06-09 11:03 ` Jiri Kosina
2014-06-09 11:03 ` Jiri Kosina
2014-06-10 11:50 ` Bisecting the heisenbugs (was Re: 3.15-rc: regression in suspend) Pavel Machek
2014-06-10 11:50 ` Pavel Machek
2014-06-21 20:29 ` 3.16, i915: less colors in X? Pavel Machek
2014-06-21 20:29 ` Pavel Machek
2014-06-21 20:35 ` Pavel Machek
2014-06-21 21:06 ` Chris Wilson
2014-06-21 21:06 ` Chris Wilson
2014-06-22 14:26 ` Pavel Machek
2014-06-22 14:26 ` Pavel Machek
2014-06-22 15:11 ` regression: 3.16, i915: less colors in X?, caused by 773875bfb6737982903c42d1ee88cf60af80089c Pavel Machek
2014-06-21 21:16 ` 3.16, i915: less colors in X? Martin Steigerwald
[not found] ` <7569_1403385738_53A5F78A_7569_14810_1_2527490.06bevSLs0l@merkaba>
2014-06-21 22:51 ` Thomas Richter [this message]
2014-06-22 10:02 ` Martin Steigerwald
2014-06-25 22:35 ` 3.15-rc: regression in suspend Pavel Machek
2014-06-25 22:35 ` Pavel Machek
2014-06-27 13:37 ` Jiri Kosina
2014-06-27 13:37 ` Jiri Kosina
2014-07-07 8:39 ` Daniel Vetter
2014-07-07 8:39 ` Daniel Vetter
2014-07-11 19:26 ` Pavel Machek
2014-07-11 23:33 ` Jiri Kosina
2014-07-11 23:33 ` Jiri Kosina
2014-08-07 12:47 ` Jiri Kosina
2014-08-07 12:47 ` Jiri Kosina
2014-08-07 12:54 ` Jiri Kosina
2014-08-07 12:54 ` Jiri Kosina
2014-08-07 14:36 ` [Intel-gfx] " Daniel Vetter
2014-08-07 14:36 ` Daniel Vetter
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