From db04b56b1238755405312341055a3d64d4ea1858 Mon Sep 17 00:00:00 2001 From: Mark Weiman Date: Fri, 29 Sep 2017 17:34:27 -0400 Subject: [PATCH] i915: Add module option to support VGA arbiter on HD devices (4.13+) This is an updated version of Alex Williamson's patch from: https://lkml.org/lkml/2014/5/9/517 I don't have i915 graphics, so this is completely untested. Original commit message follows: --- Commit 81b5c7bc found that the current VGA arbiter support in i915 only works for ancient GMCH-based IGD devices and attempted to update support for newer HD devices. Unfortunately newer devices cannot completely opt-out of VGA arbitration like the old devices could. The VGA I/O space cannot be disabled internally. The only way to route VGA I/O elsewhere is by disabling I/O at the device PCI command register. This means that with commit 81b5c7bc and multiple VGA adapters, the VGA arbiter will report that multiple VGA devices are participating in arbitration, Xorg will notice this and disable DRI. Therefore, 81b5c7bc was reverted because DRI is more important than being correct. There is however an actual need for i915 to correctly participate in VGA arbitration; VGA device assignment. If we want to use VFIO to assign a VGA device to a virtual machine, we need to be able to access the VGA resources of that device. By adding an i915 module option we can allow i915 to continue with its charade by default, but also allow an easy path for users who require working VGA arbitration. Hopefully Xorg can someday be taught to behave better with multiple VGA devices. This also rolls in reverted commit 6e1b4fda, which corrected an ordering issue with 81b5c7bc by delaying the disabling of VGA memory until after vgacon->fbcon handoff. --- drivers/gpu/drm/i915/i915_drv.c | 22 +++++++++++++++++++--- drivers/gpu/drm/i915/i915_params.c | 5 +++++ drivers/gpu/drm/i915/i915_params.h | 1 + drivers/gpu/drm/i915/intel_display.c | 34 ++++++++++++++++++++++++++++++++++ drivers/gpu/drm/i915/intel_drv.h | 1 + 5 files changed, 60 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index fc307e03943c..742039c1f1c7 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -614,10 +614,20 @@ static int i915_load_modeset_init(struct drm_device *dev) * If we are a secondary display controller (!PCI_DISPLAY_CLASS_VGA), * then we do not take part in VGA arbitration and the * vga_client_register() fails with -ENODEV. + * + * NB. The set_decode callback here actually works on GMCH + * devices, on newer HD devices we can only disable VGA MMIO space. + * Disabling VGA I/O space requires disabling I/O in the PCI command + * register. Nonetheless, we like to pretend that we participate in + * VGA arbitration and can dynamically disable VGA I/O space because + * this makes X happy, even though it's a complete lie. */ - ret = vga_client_register(pdev, dev_priv, NULL, i915_vga_set_decode); - if (ret && ret != -ENODEV) - goto out; + if (!i915.enable_hd_vgaarb || !HAS_PCH_SPLIT(dev_priv)) { + ret = vga_client_register(pdev, dev, NULL, + i915_vga_set_decode); + if (ret && ret != -ENODEV) + goto out; + } intel_register_dsm_handler(); @@ -659,6 +669,12 @@ static int i915_load_modeset_init(struct drm_device *dev) if (ret) goto cleanup_gem; + /* + * Must do this after fbcon init so that + * vgacon_save_screen() works during the handover. + */ + i915_disable_vga_mem(dev_priv); + /* Only enable hotplug handling once the fbdev is fully set up. */ intel_hpd_init(dev_priv); diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c index b6a7e363d076..5883c1f98e2d 100644 --- a/drivers/gpu/drm/i915/i915_params.c +++ b/drivers/gpu/drm/i915/i915_params.c @@ -51,6 +51,7 @@ struct i915_params i915 __read_mostly = { .invert_brightness = 0, .disable_display = 0, .enable_cmd_parser = true, + .enable_hd_vgaarb = false, .use_mmio_flip = 0, .mmio_debug = 0, .verbose_state_checks = 1, @@ -194,6 +195,10 @@ module_param_named_unsafe(enable_cmd_parser, i915.enable_cmd_parser, bool, 0400) MODULE_PARM_DESC(enable_cmd_parser, "Enable command parsing (true=enabled [default], false=disabled)"); +module_param_named(enable_hd_vgaarb, i915.enable_hd_vgaarb, bool, 0444); +MODULE_PARM_DESC(enable_hd_vgaarb, + "Enable support for VGA arbitration on Intel HD IGD. (default: false)"); + module_param_named_unsafe(use_mmio_flip, i915.use_mmio_flip, int, 0600); MODULE_PARM_DESC(use_mmio_flip, "use MMIO flips (-1=never, 0=driver discretion [default], 1=always)"); diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h index 34148cc8637c..edc38206d360 100644 --- a/drivers/gpu/drm/i915/i915_params.h +++ b/drivers/gpu/drm/i915/i915_params.h @@ -63,6 +63,7 @@ func(bool, reset); \ func(bool, error_capture); \ func(bool, disable_display); \ + func(bool, enable_hd_vgaarb); \ func(bool, verbose_state_checks); \ func(bool, nuclear_pageflip); \ func(bool, enable_dp_mst); \ diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index cc484b56eeaa..1d0e504f32ee 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -14883,6 +14883,37 @@ static void i915_disable_vga(struct drm_i915_private *dev_priv) POSTING_READ(vga_reg); } +static void i915_enable_vga_mem(struct drm_i915_private *dev_priv) +{ + struct pci_dev *pdev = dev_priv->drm.pdev; + + /* Enable VGA memory on Intel HD */ + if (i915.enable_hd_vgaarb && HAS_PCH_SPLIT(dev_priv)) { + vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO); + outb(inb(VGA_MSR_READ) | VGA_MSR_MEM_EN, VGA_MSR_WRITE); + vga_set_legacy_decoding(pdev, VGA_RSRC_LEGACY_IO | + VGA_RSRC_LEGACY_MEM | + VGA_RSRC_NORMAL_IO | + VGA_RSRC_NORMAL_MEM); + vga_put(pdev, VGA_RSRC_LEGACY_IO); + } +} + +void i915_disable_vga_mem(struct drm_i915_private *dev_priv) +{ + struct pci_dev *pdev = dev_priv->drm.pdev; + + /* Disable VGA memory on Intel HD */ + if (i915.enable_hd_vgaarb && HAS_PCH_SPLIT(dev_priv)) { + vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO); + outb(inb(VGA_MSR_READ) & ~VGA_MSR_MEM_EN, VGA_MSR_WRITE); + vga_set_legacy_decoding(pdev, VGA_RSRC_LEGACY_IO | + VGA_RSRC_NORMAL_IO | + VGA_RSRC_NORMAL_MEM); + vga_put(pdev, VGA_RSRC_LEGACY_IO); + } +} + void intel_modeset_init_hw(struct drm_device *dev) { struct drm_i915_private *dev_priv = to_i915(dev); @@ -15381,6 +15412,7 @@ void i915_redisable_vga_power_on(struct drm_i915_private *dev_priv) if (!(I915_READ(vga_reg) & VGA_DISP_DISABLE)) { DRM_DEBUG_KMS("Something enabled VGA plane, disabling it\n"); i915_disable_vga(dev_priv); + i915_disable_vga_mem(dev_priv); } } @@ -15732,6 +15764,8 @@ void intel_modeset_cleanup(struct drm_device *dev) { struct drm_i915_private *dev_priv = to_i915(dev); + i915_enable_vga_mem(dev_priv); + flush_work(&dev_priv->atomic_helper.free_work); WARN_ON(!llist_empty(&dev_priv->atomic_helper.free_list)); diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index d93efb49a2e2..cdd474ba61f9 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -1336,6 +1336,7 @@ int vlv_get_cck_clock_hpll(struct drm_i915_private *dev_priv, void lpt_disable_pch_transcoder(struct drm_i915_private *dev_priv); void lpt_disable_iclkip(struct drm_i915_private *dev_priv); extern const struct drm_plane_funcs intel_plane_funcs; +extern void i915_disable_vga_mem(struct drm_i915_private *dev_priv); void intel_init_display_hooks(struct drm_i915_private *dev_priv); unsigned int intel_fb_xy_to_linear(int x, int y, const struct intel_plane_state *state, -- 2.14.2