Created attachment 18239 [details] [review] Xorg log This is tested on Ubuntu Intrepid, using the default xorg.conf which defaults to the radeon driver. This results in banding across the display.
Created attachment 18698 [details] Photo showing banding Mario sent me the hardware in question; I've taken a photo of the screen to illustrate the banding. This is with -ati version 1:6.9.0+git20080802.1f3eee36-1ubuntu1. I'll test with the a3cc1d7a once it's built.
Some additional details... This seems to only occur with gradients. I can reproduce the issue both in Inkscape and Gimp when using their gradients.
Dithering is probably enabled for that output. You'd need to fix up dfp_disable_dither() in atombios_output.c for DCE 3.0 cards.
Noticed that the log didn't specify the pci info: 01:00.0 VGA compatible controller [0300]: ATI Technologies Inc Radeon Mobility HD 3670 [1002:9593] Subsystem: Dell Device [1028:0272]
Created attachment 18990 [details] [review] rv635_dithering.patch I'm having some trouble determining what register needs to be poked. I've tried all the ones in the current code, and tried finding some docs to see if there is a new BIT_DEPTH_CONTROL register, but no luck so far. Maybe something has to be done in addition to setting the bit depth?
I've also tried each of the following without luck: OUTREG(0x6710, 0); OUTREG(0x6f10, 0);
Created attachment 19105 [details] [review] Enable dithering on rv635 hardware After a whole bunch of experimentation and advice from Alex, this patch enables dithering and greatly diminishes the banding. (The banding's still there, but you have to look close to see it.)
Alex, please let me know if there are changes you'd like to see to this patch before it can be committed to upstream git. I've incorporated it into Ubuntu's -ati package.
Is this bug supposed to be fixed with current git?
(In reply to comment #9) > Is this bug supposed to be fixed with current git? > Ajax' commit (d744dc013cf5ca3141c0fdf55e36d713fe9f53ba) should fix it I think.
I finally got a chance to re-test this. Unfortunately, it did not eliminate the banding. At least it seems to be no worse than the patch I'd posted earlier, but the banding is still present if you look closely.
Is this still an issue with ati git master?
closing due to lack of feedback.
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