Re: radeonfb broken

[Timothy Miller <miller@techsource.com>]

Andrew Morton asked me to repost the patch for the Radeon FB off-by-one 
bug.  I'll see about making a proper patch when I get home, but if you 
want to fix it quicker, I'll just tell you what to change.


In the druvers/video/radeonfb.c, there is a function called 
fbcon_radeon_bmove.  In there, you'll see this code:

	if (srcy < dsty) {
                 srcy += height;
                 dsty += height;
         } else
                 dp_cntl |= DST_Y_TOP_TO_BOTTOM;

         if (srcx < dstx) {
                 srcx += width;
                 dstx += width;
         } else
                 dp_cntl |= DST_X_LEFT_TO_RIGHT;


Those adds need to be reduced by one.  The code should look like this:


	if (srcy < dsty) {
                 srcy += height - 1;
                 dsty += height - 1;
         } else
                 dp_cntl |= DST_Y_TOP_TO_BOTTOM;

         if (srcx < dstx) {
                 srcx += width - 1;
                 dstx += width - 1;
         } else
                 dp_cntl |= DST_X_LEFT_TO_RIGHT;



This bug is in the mainline kernel, and since I have direct experience 
programming for the Radeon, I knew how to fix it, but I also noticed 
that the Red Hat kernel "2.4.18-27.7.x" has the proper fix in it.


Whenever I download a new 2.4 kernel for gentoo, I have to manually make 
that fix.  I'm also disappointed that acceleration for Radeon has 
disappeared completely from 2.6.