Re: [PATCH 4/6] drm/i915: don't memset the fb buffer if preallocated

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Sat, 14 Dec 2013 12:28:49 +0100
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Thu, Dec 12, 2013 at 12:41:55PM -0800, Jesse Barnes wrote:
> > We want to preserve the BIOS/bootloader contents for later.
> > 
> > Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> > ---
> >  drivers/gpu/drm/i915/intel_fbdev.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
> > index db75f22..53675d2 100644
> > --- a/drivers/gpu/drm/i915/intel_fbdev.c
> > +++ b/drivers/gpu/drm/i915/intel_fbdev.c
> > @@ -132,6 +132,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
> >  	struct drm_framebuffer *fb;
> >  	struct drm_i915_gem_object *obj;
> >  	int size, ret;
> > +	bool prealloc = false;
> >  
> >  	mutex_lock(&dev->struct_mutex);
> >  
> > @@ -142,6 +143,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
> >  			goto out_unlock;
> >  	} else {
> >  		DRM_DEBUG_KMS("re-using BIOS fb\n");
> > +		prealloc = true;
> >  		sizes->fb_width = intel_fb->base.width;
> >  		sizes->fb_height = intel_fb->base.height;
> >  	}
> > @@ -203,7 +205,7 @@ static int intelfb_create(struct drm_fb_helper *helper,
> >  	 * If the object is stolen however, it will be full of whatever
> >  	 * garbage was left in there.
> >  	 */
> > -	if (ifbdev->fb->obj->stolen)
> > +	if (ifbdev->fb->obj->stolen && !prealloc)
> >  		memset_io(info->screen_base, 0, info->screen_size);
> 
> Shouldn't we just move this into intelfb_alloc? Now that allocating our
> own fb isn't the only way any more to get at one this code + comment above
> looks a bit misplaced.

We can't since we haven't ioremapped the buffer and such until after
the alloc or reuse.  It's a little awkward, I agree, but we need more
refactoring on the fbdev code to make it look nice.

-- 
Jesse Barnes, Intel Open Source Technology Center