Regression: drm: Lobotomize set_busid nonsense for !pci drivers (a325725633c2)

[Daniel Vetter]

On Wed, Oct 05, 2016 at 08:34:57AM +0200, Gerd Hoffmann wrote:
> On Di, 2016-10-04 at 09:43 +0200, Gerd Hoffmann wrote:
> >   Hi,
> > 
> > > diff --git a/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
> > > b/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
> > > index a59d0e309bfc..1fcf739bf509 100644
> > > --- a/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
> > > +++ b/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
> > > @@ -68,6 +68,10 @@ int drm_virtio_init(struct drm_driver *driver,
> > > struct virtio_device *vdev)
> > >                 dev->pdev = pdev;
> > >                 if (vga)
> > >                         virtio_pci_kick_out_firmware_fb(pdev);
> > > +
> > > +               ret = drm_dev_set_unique(dev, dev_name(dev->pdev));
> > > +               if (ret)
> > > +                       goto err_free;
> > >         }
> > 
> > Approach looks sensible to me, I'll give it a try ...
> 
> Well, dev_name() returns a string without the "pci:" prefix, we have to
> add that to make things actually work, like this:

Hm right, I missed that in digging through the piles of layers of struct
device naming.

> 
> --- a/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_drm_bus.c
> @@ -60,13 +60,22 @@ int drm_virtio_init(struct drm_driver *driver,
> struct virtio_device *vdev)
>  
>         if (strcmp(vdev->dev.parent->bus->name, "pci") == 0) {
>                 struct pci_dev *pdev = to_pci_dev(vdev->dev.parent);
> +               const char *pname = dev_name(&pdev->dev);
>                 bool vga = (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
> +               char unique[20];

Iirc we kfree this on unload. Needs to be a kasprintf I think.
>  
> -               DRM_INFO("pci: %s detected\n",
> -                        vga ? "virtio-vga" : "virtio-gpu-pci");
> +               DRM_INFO("pci: %s detected at %s\n",
> +                        vga ? "virtio-vga" : "virtio-gpu-pci",
> +                        pname);
>                 dev->pdev = pdev;
>                 if (vga)
>                         virtio_pci_kick_out_firmware_fb(pdev);
> +
> +               snprintf(unique, sizeof(unique), "pci:%s", pname);
> +               ret = drm_dev_set_unique(dev, unique);
> +               if (ret)
> +                       goto err_free;
> +

I think once we can nuke the pci_setbusid stuff we might want a
drm_dev_pci_set_unique, which takes the struct pci_device and wraps the
above magic. But that can wait, we still have a few years on the uabi
clock for that.

Strictly speaking this is an issue for virtgpu too, but since virtgpu is
newer than the last broken libdrm release I think we'll be fine.

With the kasprintf change above:

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

>         }
>  
>         ret = drm_dev_register(dev, 0);
> 
> And a partial revert of commit a742946a1ba57e24e8be205ea87224c05b38c380
> to re-export drm_dev_set_unique().
> 
> Pushed to git://git.kraxel.org/linux drm-qemu
> 
> cheers,
>   Gerd
> 

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