Re: [PATCH v2] drm/qxl: get vga ioports

[David Airlie <airlied@redhat.com>]

Reviewed-by: Dave Airlie <airlied@redhat.com>

On Thu, Aug 22, 2019 at 4:59 PM Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> On Mon, Aug 05, 2019 at 12:54:01PM +0200, Gerd Hoffmann wrote:
> > qxl has two modes: "native" (used by the drm driver) and "vga" (vga
> > compatibility mode, typically used for boot display and firmware
> > framebuffers).
> >
> > Accessing any vga ioport will switch the qxl device into vga mode.
> > The qxl driver never does that, but other drivers accessing vga ports
> > can trigger that too and therefore disturb qxl operation.  So aquire
> > the legacy vga ioports from vgaarb to avoid that.
> >
> > Reproducer: Boot kvm guest with both qxl and i915 vgpu, with qxl being
> > first in pci scan order.
> >
> > v2: Skip this for secondary qxl cards which don't have vga mode in the
> >     first place (Frediano).
>
> Ping, any chance for an ack?
>
> thanks,
>   Gerd
>
> >
> > Cc: Frediano Ziglio <fziglio@redhat.com>
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> > ---
> >  drivers/gpu/drm/qxl/qxl_drv.c | 20 +++++++++++++++++++-
> >  1 file changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
> > index b57a37543613..fcb48ac60598 100644
> > --- a/drivers/gpu/drm/qxl/qxl_drv.c
> > +++ b/drivers/gpu/drm/qxl/qxl_drv.c
> > @@ -63,6 +63,11 @@ module_param_named(num_heads, qxl_num_crtc, int, 0400);
> >  static struct drm_driver qxl_driver;
> >  static struct pci_driver qxl_pci_driver;
> >
> > +static bool is_vga(struct pci_dev *pdev)
> > +{
> > +     return pdev->class == PCI_CLASS_DISPLAY_VGA << 8;
> > +}
> > +
> >  static int
> >  qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> >  {
> > @@ -87,9 +92,17 @@ qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> >       if (ret)
> >               goto disable_pci;
> >
> > +     if (is_vga(pdev)) {
> > +             ret = vga_get_interruptible(pdev, VGA_RSRC_LEGACY_IO);
> > +             if (ret) {
> > +                     DRM_ERROR("can't get legacy vga ioports\n");
> > +                     goto disable_pci;
> > +             }
> > +     }
> > +
> >       ret = qxl_device_init(qdev, &qxl_driver, pdev);
> >       if (ret)
> > -             goto disable_pci;
> > +             goto put_vga;
> >
> >       ret = qxl_modeset_init(qdev);
> >       if (ret)
> > @@ -109,6 +122,9 @@ qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> >       qxl_modeset_fini(qdev);
> >  unload:
> >       qxl_device_fini(qdev);
> > +put_vga:
> > +     if (is_vga(pdev))
> > +             vga_put(pdev, VGA_RSRC_LEGACY_IO);
> >  disable_pci:
> >       pci_disable_device(pdev);
> >  free_dev:
> > @@ -126,6 +142,8 @@ qxl_pci_remove(struct pci_dev *pdev)
> >
> >       qxl_modeset_fini(qdev);
> >       qxl_device_fini(qdev);
> > +     if (is_vga(pdev))
> > +             vga_put(pdev, VGA_RSRC_LEGACY_IO);
> >
> >       dev->dev_private = NULL;
> >       kfree(qdev);
> > --
> > 2.18.1
> >
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