Mailinglist Archive: radeonhd (699 mails)

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Re: [radeonhd] Dithering, how to disable
  • From: Pierre Ossman <drzeus-list@xxxxxxxxx>
  • Date: Fri, 2 Nov 2007 12:53:17 +0100
  • Message-id: <20071102125317.4d4931e8@xxxxxxxxxxxxxxxxxx>
On Fri, 2 Nov 2007 10:56:19 +0100
Luc Verhaegen <libv@xxxxxxxxx> wrote:

Could it be that it really is a 24bit panel and that, since we do not
know any better, we set it up as an 18bit panel and it still works?
When i'm back in the office; i should probably try to set up the hp
laptop as 24bits. This laptop is a mobility r5xx, 1680x1050, so i was
initially quite surprised to see that it was only an 18bit panel. Iirc,
i attempted to drive it differently, without success, but this was in
the hectic days right before XDS.

Great. Let me know how at goes, and if there is anything I can test here.

Please describe what you mean by grainy? Could there be something else
going on besides dithering? I hope it is not something as
straightforward as adjusting gamma.

A solid white (3 x 0xff) does not give a solid color or brightness. It looks
almost identical to a panel covered in dust.

I had a chat with Lenovo and they couldn't tell me of any known issues (despite
the fact that you can find lots of forum posts where people have experienced
recent thinkpads having this issue). They speculated that it might be a
backlight effect where it doesn't give a proper, constant light. I'm sceptical
though as the variation is on a pixel scale, and I would suspect an uneven
backlight spread would give larger fluctuations.

(They also don't consider this problem big enough to warrant a repair, so I'm
stuck with solving it myself or trying to return the machine)

-- Pierre Ossman

Linux kernel, MMC maintainer
PulseAudio, core developer
rdesktop, core developer
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