Re: [PATCH] drm/i915: Properly track domain of the fbcon fb

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jun 18, 2014 at 03:57:49PM +0100, Chris Wilson wrote:
> On Wed, Jun 18, 2014 at 03:05:19PM +0200, Daniel Vetter wrote:
> > X could end up putting the fbcon fb into other domains, e.g.
> > for smooth take-overs. Also we want this for accurate frontbuffer
> > tracking: The set_config is an implicit flush and will re-enable
> > psr and similar features, so we need to bring the bo back into
> > the gtt domain.
> > 
> > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > ---
> >  drivers/gpu/drm/i915/intel_fbdev.c | 21 ++++++++++++++++++++-
> >  1 file changed, 20 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> > index 27975c3e21c5..53c50240d1c2 100644
> > --- a/drivers/gpu/drm/i915/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> > @@ -43,10 +43,29 @@
> >  #include <drm/i915_drm.h>
> >  #include "i915_drv.h"
> >  
> > +static int intel_fbdev_set_par(struct fb_info *info)
> > +{
> > +	struct drm_fb_helper *fb_helper = info->par;
> > +	struct intel_fbdev *ifbdev =
> > +		container_of(fb_helper, struct intel_fbdev, helper);
> > +	int ret;
> > +
> > +	ret = drm_fb_helper_set_par(info);
> > +
> > +	if (ret == 0) {
> 
> Add a comment here saying you are happy with the potential deadlock,
> double-fault and what not, and I'll accept it with provisons that I'll
> still worry that this will explode in our faces.

/*
 * FIXME: fbdev presumes that all callbacks also work from atomic contexts
 * and relies on that for emergency oops printing. KMS totally doesn't do
 * that and the locking here is by far not the only place this goes wrong.
 * Ignore this for now until we solve this for real.
 */

Like this?
-Daniel
> 
> > +		mutex_lock(&fb_helper->dev->struct_mutex);
> > +		ret = i915_gem_object_set_to_gtt_domain(ifbdev->fb->obj,
> > +							true);
> > +		mutex_unlock(&fb_helper->dev->struct_mutex);
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> >  static struct fb_ops intelfb_ops = {
> >  	.owner = THIS_MODULE,
> >  	.fb_check_var = drm_fb_helper_check_var,
> > -	.fb_set_par = drm_fb_helper_set_par,
> > +	.fb_set_par = intel_fbdev_set_par,
> >  	.fb_fillrect = cfb_fillrect,
> >  	.fb_copyarea = cfb_copyarea,
> >  	.fb_imageblit = cfb_imageblit,
> > -- 
> > 2.0.0
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > 
> 
> -- 
> Chris Wilson, Intel Open Source Technology Centre
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch