Bug 7691

Summary: xf86-video-fbdev doesn't work with imacfb driver from linux-2.6.18-rcX
Product: xorg Reporter: Thomas Meyer <thomas.mey>
Component: Driver/fbdevAssignee: Xorg Project Team <xorg-team>
Status: RESOLVED FIXED QA Contact:
Severity: normal    
Priority: high CC: vincent.rubiolo
Version: 7.1 (2006.05)   
Hardware: x86 (IA32)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:

Description Thomas Meyer 2006-07-30 04:46:28 UTC 
The imacfb driver from linux-2.6.16-rcX only works with the xf86-video-fbdev
driver with the option "ShadowFB "0". Without this option the display is kaputt.

See also http://bugs.gentoo.org/show_bug.cgi?id=140008.

This is maybe a problem in the imacfb driver, because it's to new?!
Comment 1 Thomas Meyer 2006-09-10 09:53:43 UTC 
when i comment this in fbdev.c. the fbdev drvier is working with the shadow fb:
//      if (fPtr->shadowFB)
//              pScrn->displayWidth = pScrn->virtualX;  /* ShadowFB handles this
correctly */
//      else
        {
                int fbbpp;
                /* FIXME: this doesn't work for all cases, e.g. when each scanline
                        has a padding which is independent from the depth
(controlfb) */
                fbdevHWGetDepth(pScrn,&fbbpp);
                pScrn->displayWidth = fbdevHWGetLineLength(pScrn)/(fbbpp >> 3);
        }

So the value of pScrn->virtualX seems to be incorrect for a color depth of 24
bit and a bitsPerPixel = 32 bit.
and the comment "[..] handles this correclty" is obvious wrong.
Comment 2 Michel Dänzer 2006-09-10 14:20:07 UTC 
The comment is correct. The fbdev driver can use whatever pitch it likes for the
shadow framebuffer. If ShadowFB doesn't work, that indicates a bug in either of

* the fbdev driver's use of the shadow module
* the shadow module
* the fbdevhw module
* imacfb

but not in this particular part of the fbdev driver code.
Comment 3 Vincent Rubiolo 2006-10-29 03:46:49 UTC 
Hello,

I can confirm I also have this bug on my Mactel 20' (I come from the
mactel-linux-devel ML). This is xorg 7.1.1 (Debian testing) w/ 2.6.18.

Is there anything we can do to help you diagnose the bug and find a fix?

Thanks for your guidance,

Vincent
Comment 5 Thomas Meyer 2006-12-28 07:00:41 UTC 
Excellent! Now the fbdev driver works correctly with the shadow framebuffer 
option. Many thanks for this fix.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.