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https://github.com/torvalds/linux
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fc8fd40eb2
So I just wanted to add a new field to struct drm_device and accidentally stumbled over something. According to comments dev->open_count is protected by dev->count_lock, but that's totally not the case. It's protected by drm_global_mutex. Unfortunately the vga switcheroo callbacks took this comment at face value. The problem is that we can't just take the drm_global_mutex because: - It would lead to a locking inversion with the driver load/unload paths. - It wouldn't actually protect anything, for that we'd need to wrap the entire vga switcheroo code in the drm_global_mutex. And I'm not sure whether that would actually solve anything. What we probably want is a try_to_grab_switcheroo reference kind of thing which is used in the driver's ->open callback. Then we could move all that ->can_switch madness into the vga switcheroo core where it really belongs. But since that would amount to real work take the easy way out and just add a comment. It's definitely not going to make anything worse since doing switcheroo state changes while restarting X just isn't recommended. Even though the delayed switching code does exactly that. v2: - Simplify the ->can_switch implementations more (Thierry) - Fix comment about the dev->open_count locking (Thierry) Cc: Thierry Reding <treding@nvidia.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> (v1) Reviewed-by: Thierry Reding <treding@nvidia.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
119 lines
3.1 KiB
C
119 lines
3.1 KiB
C
#include <linux/vgaarb.h>
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#include <linux/vga_switcheroo.h>
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#include <drm/drmP.h>
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#include <drm/drm_crtc_helper.h>
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#include "nouveau_drm.h"
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#include "nouveau_acpi.h"
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#include "nouveau_fbcon.h"
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#include "nouveau_vga.h"
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static unsigned int
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nouveau_vga_set_decode(void *priv, bool state)
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{
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struct nouveau_device *device = nouveau_dev(priv);
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if (device->card_type == NV_40 && device->chipset >= 0x4c)
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nv_wr32(device, 0x088060, state);
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else if (device->chipset >= 0x40)
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nv_wr32(device, 0x088054, state);
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else
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nv_wr32(device, 0x001854, state);
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if (state)
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return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
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VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
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else
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return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
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}
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static void
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nouveau_switcheroo_set_state(struct pci_dev *pdev,
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enum vga_switcheroo_state state)
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{
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struct drm_device *dev = pci_get_drvdata(pdev);
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if ((nouveau_is_optimus() || nouveau_is_v1_dsm()) && state == VGA_SWITCHEROO_OFF)
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return;
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if (state == VGA_SWITCHEROO_ON) {
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printk(KERN_ERR "VGA switcheroo: switched nouveau on\n");
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dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
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nouveau_pmops_resume(&pdev->dev);
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drm_kms_helper_poll_enable(dev);
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dev->switch_power_state = DRM_SWITCH_POWER_ON;
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} else {
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printk(KERN_ERR "VGA switcheroo: switched nouveau off\n");
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dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
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drm_kms_helper_poll_disable(dev);
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nouveau_switcheroo_optimus_dsm();
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nouveau_pmops_suspend(&pdev->dev);
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dev->switch_power_state = DRM_SWITCH_POWER_OFF;
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}
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}
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static void
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nouveau_switcheroo_reprobe(struct pci_dev *pdev)
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{
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struct drm_device *dev = pci_get_drvdata(pdev);
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nouveau_fbcon_output_poll_changed(dev);
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}
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static bool
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nouveau_switcheroo_can_switch(struct pci_dev *pdev)
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{
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struct drm_device *dev = pci_get_drvdata(pdev);
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/*
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* FIXME: open_count is protected by drm_global_mutex but that would lead to
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* locking inversion with the driver load path. And the access here is
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* completely racy anyway. So don't bother with locking for now.
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*/
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return dev->open_count == 0;
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}
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static const struct vga_switcheroo_client_ops
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nouveau_switcheroo_ops = {
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.set_gpu_state = nouveau_switcheroo_set_state,
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.reprobe = nouveau_switcheroo_reprobe,
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.can_switch = nouveau_switcheroo_can_switch,
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};
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void
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nouveau_vga_init(struct nouveau_drm *drm)
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{
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struct drm_device *dev = drm->dev;
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bool runtime = false;
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/* only relevant for PCI devices */
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if (!dev->pdev)
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return;
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vga_client_register(dev->pdev, dev, NULL, nouveau_vga_set_decode);
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if (nouveau_runtime_pm == 1)
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runtime = true;
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if ((nouveau_runtime_pm == -1) && (nouveau_is_optimus() || nouveau_is_v1_dsm()))
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runtime = true;
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vga_switcheroo_register_client(dev->pdev, &nouveau_switcheroo_ops, runtime);
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if (runtime && nouveau_is_v1_dsm() && !nouveau_is_optimus())
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vga_switcheroo_init_domain_pm_ops(drm->dev->dev, &drm->vga_pm_domain);
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}
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void
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nouveau_vga_fini(struct nouveau_drm *drm)
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{
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struct drm_device *dev = drm->dev;
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vga_switcheroo_unregister_client(dev->pdev);
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vga_client_register(dev->pdev, NULL, NULL, NULL);
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}
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void
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nouveau_vga_lastclose(struct drm_device *dev)
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{
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vga_switcheroo_process_delayed_switch();
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}
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