lkml.org 
[lkml]   [2014]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 1/1] drm/vmwgfx: correct fb_fix_screeninfo.line_length
On Mon, Jun 30, 2014 at 7:48 AM, Thomas Hellstrom <thellstrom@vmware.com> wrote:
> I don't think we can blame video-vmware for this. A kernel driver change
> that breaks existing user-space is by definition a kernel driver bug,
> regardless whether exisiting user-space is doing something horrendously
> stupid.

I wouldn't be so quick to say it's a kernel bug. The fbdev contract
hasn't changed. Also xf86-video-vmware isn't using the fbdev driver,
and the fbdev driver code is obviously correct (see screenshots in
link submitted with initial patch).

> So the fix must IMO be a kernel driver fix. My initial guess is that
> once we set the bytes per line register, it might not be automatically
> updated when the screen width is changed, but the documentation is poor.
> I see if I can shed some light over this.

Having dumped all of the svga registers while hacking on vmwgfx, I
noticed that the BYTES_PER_LINE field is initially incorrectly set to
something way off. My initial reaction is that video-vmware doesn't
properly compute the bytes-per-line register, and therefore that it is
a video-vmware bug that has always existed.

I'm reproducing the problem and providing a fix for video-vmware as I
write this.

C


\
 
 \ /
  Last update: 2014-06-30 15:21    [W:0.091 / U:0.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site