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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7e13ad8964
Since drm_global_mutex is a true global mutex across devices, we don't want to acquire it unless absolutely necessary. For maintaining the device local open_count, we can use atomic operations on the counter itself, except when making the transition to/from 0. Here, we tackle the easy portion of delaying acquiring the drm_global_mutex for the final release by using atomic_dec_and_mutex_lock(), leaving the global serialisation across the device opens. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Thomas Hellström (VMware) <thomas_os@shipmail.org> Reviewed-by: Thomas Hellström <thellstrom@vmware.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200124130107.125404-1-chris@chris-wilson.co.uk
68 lines
1.8 KiB
C
68 lines
1.8 KiB
C
// SPDX-License-Identifier: MIT
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/*
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* Copyright © 2019 Intel Corporation
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*/
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#include <linux/vga_switcheroo.h>
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#include "i915_drv.h"
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#include "i915_switcheroo.h"
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static void i915_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_i915_private *i915 = pdev_to_i915(pdev);
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pm_message_t pmm = { .event = PM_EVENT_SUSPEND };
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if (!i915) {
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dev_err(&pdev->dev, "DRM not initialized, aborting switch.\n");
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return;
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}
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if (state == VGA_SWITCHEROO_ON) {
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pr_info("switched on\n");
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i915->drm.switch_power_state = DRM_SWITCH_POWER_CHANGING;
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/* i915 resume handler doesn't set to D0 */
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pci_set_power_state(pdev, PCI_D0);
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i915_resume_switcheroo(i915);
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i915->drm.switch_power_state = DRM_SWITCH_POWER_ON;
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} else {
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pr_info("switched off\n");
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i915->drm.switch_power_state = DRM_SWITCH_POWER_CHANGING;
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i915_suspend_switcheroo(i915, pmm);
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i915->drm.switch_power_state = DRM_SWITCH_POWER_OFF;
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}
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}
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static bool i915_switcheroo_can_switch(struct pci_dev *pdev)
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{
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struct drm_i915_private *i915 = pdev_to_i915(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 i915 && atomic_read(&i915->drm.open_count) == 0;
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}
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static const struct vga_switcheroo_client_ops i915_switcheroo_ops = {
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.set_gpu_state = i915_switcheroo_set_state,
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.reprobe = NULL,
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.can_switch = i915_switcheroo_can_switch,
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};
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int i915_switcheroo_register(struct drm_i915_private *i915)
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{
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struct pci_dev *pdev = i915->drm.pdev;
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return vga_switcheroo_register_client(pdev, &i915_switcheroo_ops, false);
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}
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void i915_switcheroo_unregister(struct drm_i915_private *i915)
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{
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struct pci_dev *pdev = i915->drm.pdev;
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vga_switcheroo_unregister_client(pdev);
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}
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