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 --- 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);