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![Lukas Wunner](/assets/img/avatar_default.png)
Back in 2013, runtime PM for GPUs with integrated HDA controller was introduced with commits0d69704ae3
("gpu/vga_switcheroo: add driver control power feature. (v3)") and246efa4a07
("snd/hda: add runtime suspend/resume on optimus support (v4)"). Briefly, the idea was that the HDA controller is forced on and off in unison with the GPU. The original code is mostly still in place even though it was never a 100% perfect solution: E.g. on access to the HDA controller, the GPU is powered up via vga_switcheroo_runtime_resume_hdmi_audio() but there are no provisions to keep it resumed until access to the HDA controller has ceased: The GPU autosuspends after 5 seconds, rendering the HDA controller inaccessible. Additionally, a kludge is required when hda_intel.c probes: It has to check whether the GPU is powered down (check_hdmi_disabled()) and defer probing if so. However in the meantime (in v4.10) the driver core has gained a feature called device links which promises to solve such issues in a clean way: It allows us to declare a dependency from the HDA controller (consumer) to the GPU (supplier). The PM core then automagically ensures that the GPU is runtime resumed as long as the HDA controller's ->probe hook is executed and whenever the HDA controller is accessed. By default, the HDA controller has a dependency on its parent, a PCIe Root Port. Adding a device link creates another dependency on its sibling: PCIe Root Port ^ ^ | | | | HDA ===> GPU The device link is not only used for runtime PM, it also guarantees that on system sleep, the HDA controller suspends before the GPU and resumes after the GPU, and on system shutdown the HDA controller's ->shutdown hook is executed before the one of the GPU. It is a complete solution. Using this functionality is as simple as calling device_link_add(), which results in a dmesg entry like this: pci 0000:01:00.1: Linked as a consumer to 0000:01:00.0 The code for the GPU-governed audio power management can thus be removed (except where it's still needed for legacy manual power control). The device link is added in a PCI quirk rather than in hda_intel.c. It is therefore legal for the GPU to runtime suspend to D3cold even if the HDA controller is not bound to a driver or if CONFIG_SND_HDA_INTEL is not enabled, for accesses to the HDA controller will cause the GPU to wake up regardless if they're occurring outside of hda_intel.c (think config space readout via sysfs). Contrary to the previous implementation, the HDA controller's power state is now self-governed, rather than GPU-governed, whereas the GPU's power state is no longer fully self-governed. (The HDA controller needs to runtime suspend before the GPU can.) It is thus crucial that runtime PM is always activated on the HDA controller even if CONFIG_SND_HDA_POWER_SAVE_DEFAULT is set to 0 (which is the default), lest the GPU stays awake. This is achieved by setting the auto_runtime_pm flag on every codec and the AZX_DCAPS_PM_RUNTIME flag on the HDA controller. A side effect is that power consumption might be reduced if the GPU is in use but the HDA controller is not, because the HDA controller is now allowed to go to D3hot. Before, it was forced to stay in D0 as long as the GPU was in use. (There is no reduction in power consumption on my Nvidia GK107, but there might be on other chips.) The code paths for legacy manual power control are adjusted such that runtime PM is disabled during power off, thereby preventing the PM core from resuming the HDA controller. Note that the device link is not only added on vga_switcheroo capable systems, but for *any* GPU with integrated HDA controller. The idea is that the HDA controller streams audio via connectors located on the GPU, so the GPU needs to be on for the HDA controller to do anything useful. This commit implicitly fixes an unbalanced runtime PM ref upon unbind of hda_intel.c: On ->probe, a runtime PM ref was previously released under the condition "azx_has_pm_runtime(chip) || hda->use_vga_switcheroo", but on ->remove a runtime PM ref was only acquired under the first of those conditions. Thus, binding and unbinding the driver twice on a vga_switcheroo capable system caused the runtime PM refcount to drop below zero. The issue is resolved because the AZX_DCAPS_PM_RUNTIME flag is now always set if use_vga_switcheroo is true. For more information on device links please refer to: https://www.kernel.org/doc/html/latest/driver-api/device_link.html Documentation/driver-api/device_link.rst Cc: Dave Airlie <airlied@redhat.com> Cc: Ben Skeggs <bskeggs@redhat.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Takashi Iwai <tiwai@suse.de> Reviewed-by: Peter Wu <peter@lekensteyn.nl> Tested-by: Kai Heng Feng <kai.heng.feng@canonical.com> # AMD PowerXpress Tested-by: Mike Lothian <mike@fireburn.co.uk> # AMD PowerXpress Tested-by: Denis Lisov <dennis.lissov@gmail.com> # Nvidia Optimus Tested-by: Peter Wu <peter@lekensteyn.nl> # Nvidia Optimus Tested-by: Lukas Wunner <lukas@wunner.de> # MacBook Pro Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: https://patchwork.freedesktop.org/patch/msgid/51bd38360ff502a8c42b1ebf4405ee1d3f27118d.1520068884.git.lukas@wunner.de
196 lines
8.4 KiB
C
196 lines
8.4 KiB
C
/*
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* vga_switcheroo.h - Support for laptop with dual GPU using one set of outputs
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*
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* Copyright (c) 2010 Red Hat Inc.
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* Author : Dave Airlie <airlied@redhat.com>
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*
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* Copyright (c) 2015 Lukas Wunner <lukas@wunner.de>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS
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* IN THE SOFTWARE.
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*
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*/
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#ifndef _LINUX_VGA_SWITCHEROO_H_
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#define _LINUX_VGA_SWITCHEROO_H_
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#include <linux/fb.h>
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struct pci_dev;
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/**
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* enum vga_switcheroo_handler_flags_t - handler flags bitmask
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* @VGA_SWITCHEROO_CAN_SWITCH_DDC: whether the handler is able to switch the
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* DDC lines separately. This signals to clients that they should call
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* drm_get_edid_switcheroo() to probe the EDID
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* @VGA_SWITCHEROO_NEEDS_EDP_CONFIG: whether the handler is unable to switch
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* the AUX channel separately. This signals to clients that the active
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* GPU needs to train the link and communicate the link parameters to the
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* inactive GPU (mediated by vga_switcheroo). The inactive GPU may then
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* skip the AUX handshake and set up its output with these pre-calibrated
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* values (DisplayPort specification v1.1a, section 2.5.3.3)
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*
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* Handler flags bitmask. Used by handlers to declare their capabilities upon
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* registering with vga_switcheroo.
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*/
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enum vga_switcheroo_handler_flags_t {
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VGA_SWITCHEROO_CAN_SWITCH_DDC = (1 << 0),
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VGA_SWITCHEROO_NEEDS_EDP_CONFIG = (1 << 1),
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};
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/**
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* enum vga_switcheroo_state - client power state
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* @VGA_SWITCHEROO_OFF: off
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* @VGA_SWITCHEROO_ON: on
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* @VGA_SWITCHEROO_NOT_FOUND: client has not registered with vga_switcheroo.
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* Only used in vga_switcheroo_get_client_state() which in turn is only
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* called from hda_intel.c
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*
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* Client power state.
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*/
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enum vga_switcheroo_state {
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VGA_SWITCHEROO_OFF,
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VGA_SWITCHEROO_ON,
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/* below are referred only from vga_switcheroo_get_client_state() */
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VGA_SWITCHEROO_NOT_FOUND,
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};
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/**
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* enum vga_switcheroo_client_id - client identifier
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* @VGA_SWITCHEROO_UNKNOWN_ID: initial identifier assigned to vga clients.
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* Determining the id requires the handler, so GPUs are given their
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* true id in a delayed fashion in vga_switcheroo_enable()
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* @VGA_SWITCHEROO_IGD: integrated graphics device
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* @VGA_SWITCHEROO_DIS: discrete graphics device
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* @VGA_SWITCHEROO_MAX_CLIENTS: currently no more than two GPUs are supported
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*
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* Client identifier. Audio clients use the same identifier & 0x100.
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*/
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enum vga_switcheroo_client_id {
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VGA_SWITCHEROO_UNKNOWN_ID = -1,
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VGA_SWITCHEROO_IGD,
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VGA_SWITCHEROO_DIS,
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VGA_SWITCHEROO_MAX_CLIENTS,
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};
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/**
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* struct vga_switcheroo_handler - handler callbacks
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* @init: initialize handler.
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* Optional. This gets called when vga_switcheroo is enabled, i.e. when
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* two vga clients have registered. It allows the handler to perform
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* some delayed initialization that depends on the existence of the
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* vga clients. Currently only the radeon and amdgpu drivers use this.
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* The return value is ignored
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* @switchto: switch outputs to given client.
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* Mandatory. For muxless machines this should be a no-op. Returning 0
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* denotes success, anything else failure (in which case the switch is
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* aborted)
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* @switch_ddc: switch DDC lines to given client.
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* Optional. Should return the previous DDC owner on success or a
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* negative int on failure
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* @power_state: cut or reinstate power of given client.
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* Optional. The return value is ignored
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* @get_client_id: determine if given pci device is integrated or discrete GPU.
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* Mandatory
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*
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* Handler callbacks. The multiplexer itself. The @switchto and @get_client_id
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* methods are mandatory, all others may be set to NULL.
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*/
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struct vga_switcheroo_handler {
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int (*init)(void);
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int (*switchto)(enum vga_switcheroo_client_id id);
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int (*switch_ddc)(enum vga_switcheroo_client_id id);
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int (*power_state)(enum vga_switcheroo_client_id id,
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enum vga_switcheroo_state state);
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enum vga_switcheroo_client_id (*get_client_id)(struct pci_dev *pdev);
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};
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/**
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* struct vga_switcheroo_client_ops - client callbacks
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* @set_gpu_state: do the equivalent of suspend/resume for the card.
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* Mandatory. This should not cut power to the discrete GPU,
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* which is the job of the handler
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* @reprobe: poll outputs.
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* Optional. This gets called after waking the GPU and switching
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* the outputs to it
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* @can_switch: check if the device is in a position to switch now.
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* Mandatory. The client should return false if a user space process
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* has one of its device files open
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*
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* Client callbacks. A client can be either a GPU or an audio device on a GPU.
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* The @set_gpu_state and @can_switch methods are mandatory, @reprobe may be
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* set to NULL. For audio clients, the @reprobe member is bogus.
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*/
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struct vga_switcheroo_client_ops {
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void (*set_gpu_state)(struct pci_dev *dev, enum vga_switcheroo_state);
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void (*reprobe)(struct pci_dev *dev);
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bool (*can_switch)(struct pci_dev *dev);
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};
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#if defined(CONFIG_VGA_SWITCHEROO)
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void vga_switcheroo_unregister_client(struct pci_dev *dev);
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int vga_switcheroo_register_client(struct pci_dev *dev,
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const struct vga_switcheroo_client_ops *ops,
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bool driver_power_control);
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int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
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const struct vga_switcheroo_client_ops *ops,
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enum vga_switcheroo_client_id id);
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void vga_switcheroo_client_fb_set(struct pci_dev *dev,
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struct fb_info *info);
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int vga_switcheroo_register_handler(const struct vga_switcheroo_handler *handler,
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enum vga_switcheroo_handler_flags_t handler_flags);
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void vga_switcheroo_unregister_handler(void);
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enum vga_switcheroo_handler_flags_t vga_switcheroo_handler_flags(void);
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int vga_switcheroo_lock_ddc(struct pci_dev *pdev);
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int vga_switcheroo_unlock_ddc(struct pci_dev *pdev);
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int vga_switcheroo_process_delayed_switch(void);
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bool vga_switcheroo_client_probe_defer(struct pci_dev *pdev);
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enum vga_switcheroo_state vga_switcheroo_get_client_state(struct pci_dev *dev);
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int vga_switcheroo_init_domain_pm_ops(struct device *dev, struct dev_pm_domain *domain);
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void vga_switcheroo_fini_domain_pm_ops(struct device *dev);
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#else
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static inline void vga_switcheroo_unregister_client(struct pci_dev *dev) {}
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static inline int vga_switcheroo_register_client(struct pci_dev *dev,
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const struct vga_switcheroo_client_ops *ops, bool driver_power_control) { return 0; }
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static inline void vga_switcheroo_client_fb_set(struct pci_dev *dev, struct fb_info *info) {}
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static inline int vga_switcheroo_register_handler(const struct vga_switcheroo_handler *handler,
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enum vga_switcheroo_handler_flags_t handler_flags) { return 0; }
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static inline int vga_switcheroo_register_audio_client(struct pci_dev *pdev,
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const struct vga_switcheroo_client_ops *ops,
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enum vga_switcheroo_client_id id) { return 0; }
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static inline void vga_switcheroo_unregister_handler(void) {}
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static inline enum vga_switcheroo_handler_flags_t vga_switcheroo_handler_flags(void) { return 0; }
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static inline int vga_switcheroo_lock_ddc(struct pci_dev *pdev) { return -ENODEV; }
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static inline int vga_switcheroo_unlock_ddc(struct pci_dev *pdev) { return -ENODEV; }
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static inline int vga_switcheroo_process_delayed_switch(void) { return 0; }
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static inline bool vga_switcheroo_client_probe_defer(struct pci_dev *pdev) { return false; }
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static inline enum vga_switcheroo_state vga_switcheroo_get_client_state(struct pci_dev *dev) { return VGA_SWITCHEROO_ON; }
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static inline int vga_switcheroo_init_domain_pm_ops(struct device *dev, struct dev_pm_domain *domain) { return -EINVAL; }
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static inline void vga_switcheroo_fini_domain_pm_ops(struct device *dev) {}
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#endif
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#endif /* _LINUX_VGA_SWITCHEROO_H_ */
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