[PATCH 2/3] drm: Make drm_gem_fb_alloc available for drivers to use

[Daniel Vetter]

On Wed, Aug 15, 2018 at 12:08:38PM +0100, Liviu Dudau wrote:
> On Thu, Jul 26, 2018 at 03:10:04PM +0100, Alexandru Gheorghe wrote:
> > Some drivers can't use drm_gem_fb_create, so instead of copying the
> > logic that does the framebuffer allocation allow them to use core
> > drm_gem_fb_alloc.
> > 
> > Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe at arm.com>
> 
> To me it looks like an useful thing to have exported, so for what is worth:
> 
> Acked-by: Liviu Dudau <liviu.dudau at arm.com>
> 
> Sean, Maarten, Laurent, Gustavo, Daniel(s), do you have any objections?

In general please add meaningful kernel-doc for exported functions,
explaing what's different and how it works together.

Wrt the specific issue, I think we should teach drm core and helpers how
to allocate formats with tiled blocks. Means we need to extend
drm_format_info a bit. Your YUV formats won't be the only ones where the
format itself arranges pixels in blocks, and hence has format-based
alignment criteria for pitch and size (due to line rounding).

I think this would also fit better into the overall design where drivers
can overwrite the drm_format_info for specific (fourcc, modifier)
combinations.
-Daniel


> 
> Best regards,
> Liviu
> 
> > ---
> >  drivers/gpu/drm/drm_gem_framebuffer_helper.c | 3 ++-
> >  include/drm/drm_gem_framebuffer_helper.h     | 5 +++++
> >  2 files changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> > index 2810d4131411..64eddf5a1bd9 100644
> > --- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> > +++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
> > @@ -57,7 +57,7 @@ struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
> >  }
> >  EXPORT_SYMBOL_GPL(drm_gem_fb_get_obj);
> >  
> > -static struct drm_framebuffer *
> > +struct drm_framebuffer *
> >  drm_gem_fb_alloc(struct drm_device *dev,
> >  		 const struct drm_mode_fb_cmd2 *mode_cmd,
> >  		 struct drm_gem_object **obj, unsigned int num_planes,
> > @@ -85,6 +85,7 @@ drm_gem_fb_alloc(struct drm_device *dev,
> >  
> >  	return fb;
> >  }
> > +EXPORT_SYMBOL_GPL(drm_gem_fb_alloc);
> >  
> >  /**
> >   * drm_gem_fb_destroy - Free GEM backed framebuffer
> > diff --git a/include/drm/drm_gem_framebuffer_helper.h b/include/drm/drm_gem_framebuffer_helper.h
> > index a38de7eb55b4..d20c1356000a 100644
> > --- a/include/drm/drm_gem_framebuffer_helper.h
> > +++ b/include/drm/drm_gem_framebuffer_helper.h
> > @@ -14,6 +14,11 @@ struct drm_simple_display_pipe;
> >  
> >  struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
> >  					  unsigned int plane);
> > +struct drm_framebuffer *
> > +drm_gem_fb_alloc(struct drm_device *dev,
> > +		 const struct drm_mode_fb_cmd2 *mode_cmd,
> > +		 struct drm_gem_object **obj, unsigned int num_planes,
> > +		 const struct drm_framebuffer_funcs *funcs);
> >  void drm_gem_fb_destroy(struct drm_framebuffer *fb);
> >  int drm_gem_fb_create_handle(struct drm_framebuffer *fb, struct drm_file *file,
> >  			     unsigned int *handle);
> > -- 
> > 2.18.0
> > 
> 
> -- 
> ====================
> | I would like to |
> | fix the world,  |
> | but they're not |
> | giving me the   |
>  \ source code!  /
>   ---------------
>     ¯\_(ツ)_/¯

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch