[git pull] drm udl fixes

[Mikulas Patocka]

On Tue, 4 Sep 2018, Daniel Vetter wrote:

> On Tue, Sep 4, 2018 at 1:41 AM, Dave Airlie <airlied at gmail.com> wrote:
> >>
> >> I've seen that you dropped this patch:
> >> https://patchwork.kernel.org/patch/10445393/
> >>
> >> Is that patch correct or incorrect? In case it is incorrect, do you have
> >> an idea how should fbdefio be used properly on KMS drivers?
> >
> > I suppose I was wondering what use fbdefio really has, modern code
> > should be using KMS interface and the KMS dirty handling should be
> > able to cover those cases.

I use fbdefio with the links 2 web browser and with fbi and fbgs image
viewers.

I tried to look into modifying the links browser to work without fbdefio - 
but the DRM_IOCTL_MODE_DIRTYFB ioctl requires master mode, which means 
that it is unuseable by an unprivileged process. If you suggest how should 
console applications use the framebuffer without fbdefio, I can implement 
it.

> > I don't really like the maintainability decrease moving to in-driver 
> > page handling causes vs using shmem.
> 
> I think tinydrm has the same problem of shmem+fbdefio, could be worth
> it to chat with Noralf. Adding him.

Perhaps we could allocate tiny structures that point to pages and 
construct the list from them - but it would require rewriting all the 
fbdefio drivers, and I wonder if anyone has all the hardware that uses 
fbdefio to test it.

Mikulas