From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hendricks Reply-To: khendricks@ivey.uwo.ca To: Kostas Gewrgiou , Ani Joshi Subject: Found bug in mode switching but who is at fault...XFree86 or aty128fb.c? Date: Fri, 24 Mar 2000 22:54:51 -0500 Content-Type: text/plain Cc: linuxppc-dev@lists.linuxppc.org References: <00032313263100.01328@localhost.localdomain> In-Reply-To: <00032313263100.01328@localhost.localdomain> MIME-Version: 1.0 Message-Id: <00032423100100.00584@localhost.localdomain> Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Hi, I figured since the fbdev driver showed the same problem as the r128 driver, that the mode switching problem must be in either aty128fb.c or xfree86 but not in the r128 driver. Okay so I found the bug. It seems all through the r128 driver, crtc.pitch values are set to the virtual x resolution (vxres) / 8. But in aty128fb.c in the var_to_crtc routine the crtc.pitch is set to be just the xres / 8. This is not a problem if xres == vxres. Which is what happens when the aty128fb.c starts up. So for any one mode it defaults to being okay. However, when doing mode switching via the Cntl-Alt-Keypad+- keys, xfree sets vxres and vyres to be the same as the resolution of the largest mode on that line (so 1152x870 becomes my vxres, and vyres when 1152x870, 832x624, 1024x768 are all specified on the same line. This results in a call to aty128fb_set-var which calls decode_var which calls var_to_crtc. which gets the crtc.pitch wrong. So my questions is as follows? Who is wrong? Should xfree shrink the vxres and vyres to match xres and yres before calling set_var or should aty128fb.c var_to_crtc routine be fixed to use vxres >> 3 instead of just xres >> 3? If aty128fb.c needs to be fixed, here is a patch: --- aty128fb.c.last Sat Mar 18 23:04:24 2000 +++ aty128fb.c Fri Mar 24 22:39:26 2000 @@ -794,8 +794,11 @@ crtc->v_sync_strt_wid = v_sync_strt | (v_sync_wid << 16) | (v_sync_pol << 23); +#if 0 crtc->pitch = xres >> 3; - +#else + crtc->pitch = vxres >> 3; +#endif crtc->offset = 0; crtc->offset_cntl = 0; But I am not sure if this makes sense alone. What use is it to get a nice 832x624 hole into a display that is virtually 1152x870?!? I can't get to any of the kde controls, panels, etc since they are off the screen! And it would be a pain to have to pan around looking for them (especially since the ioctl for panning is on the "to do" list!). So my feeling is that both are wrong. We should shrink the virtual resolution to match the physical resolution in xfree when mode switching and put the patch in place in aty128fb.c Comments? Thanks, Kevin -- Kevin B. Hendricks Associate Professor of Operations and Information Technology Richard Ivey School of Business, University of Western Ontario London, Ontario N6A-3K7 CANADA khendricks@ivey.uwo.ca, (519) 661-3874, fax: 519-661-3959 ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/