Re: [PATCH] drm: set DRM_RENDER_ALLOW flag on DRM_IOCTL_MODE_CREATE/DESTROY_DUMB ioctls

[Dongwon Kim <dongwon.kim@intel.com>]

Understood. I saw weston client apps were failing to create render buffers
from kmsro driver and found it was because they were not allowed to
create and destroy dumb objects then I came up with this patch. I just thought
it's the simplest solution. I didn't know it violates the rule. I think I should
look into kmsro to make the client app to get the render buffer from
ro-device instead. Thanks

On Fri, Jun 11, 2021 at 11:39:46AM +0100, Emil Velikov wrote:
> On Fri, 11 Jun 2021 at 10:47, Daniel Vetter <daniel@ffwll.ch> wrote:
> >
> > On Thu, Jun 10, 2021 at 02:36:59PM -0700, Dongwon Kim wrote:
> > > Render clients should be able to create/destroy dumb object to import
> > > and use it as render buffer in case the default DRM device is different
> > > from the render device (i.e. kmsro).
> > >
> > > Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
> >
> > Uh no.
> >
> > Well I know everyone just hacks around this, but the idea behind dumb
> > buffer objects is that they're for kms scanout only. Furthermore on many
> > drivers they allocate a limited resource like CMA memory. Handing that out
> > like candy isn't a great idea.
> >
> > And it's exactly those drivers that kmsro currently is used for where the
> > display driver needs special memory.
> 
> Couldn't agree more. Perhaps we should add an inline comment and/or
> reference to a thread why?
> 
> -Emil