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SubjectRe: [PATCH v2] drm/qxl: get vga ioports
> 
> 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).
>
> Cc: Frediano Ziglio <fziglio@redhat.com>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Acked-by: Frediano Ziglio <fziglio@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);

Frediano

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