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|
/*
* vga_switcheroo.c - Support for laptop with dual GPU using one set of outputs
*
* Copyright (c) 2010 Red Hat Inc.
* Author : Dave Airlie <airlied@redhat.com>
*
* Copyright (c) 2015 Lukas Wunner <lukas@wunner.de>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS
* IN THE SOFTWARE.
*
*/
#define pr_fmt(fmt) "vga_switcheroo: " fmt
#include <linux/apple-gmux.h>
#include <linux/console.h>
#include <linux/debugfs.h>
#include <linux/fb.h>
#include <linux/fs.h>
#include <linux/fbcon.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/pm_domain.h>
#include <linux/pm_runtime.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/vgaarb.h>
#include <linux/vga_switcheroo.h>
/**
* DOC: Overview
*
* vga_switcheroo is the Linux subsystem for laptop hybrid graphics.
* These come in two flavors:
*
* * muxed: Dual GPUs with a multiplexer chip to switch outputs between GPUs.
* * muxless: Dual GPUs but only one of them is connected to outputs.
* The other one is merely used to offload rendering, its results
* are copied over PCIe into the framebuffer. On Linux this is
* supported with DRI PRIME.
*
* Hybrid graphics started to appear in the late Naughties and were initially
* all muxed. Newer laptops moved to a muxless architecture for cost reasons.
* A notable exception is the MacBook Pro which continues to use a mux.
* Muxes come with varying capabilities: Some switch only the panel, others
* can also switch external displays. Some switch all display pins at once
* while others can switch just the DDC lines. (To allow EDID probing
* for the inactive GPU.) Also, muxes are often used to cut power to the
* discrete GPU while it is not used.
*
* DRM drivers register GPUs with vga_switcheroo, these are henceforth called
* clients. The mux is called the handler. Muxless machines also register a
* handler to control the power state of the discrete GPU, its ->switchto
* callback is a no-op for obvious reasons. The discrete GPU is often equipped
* with an HDA controller for the HDMI/DP audio signal, this will also
* register as a client so that vga_switcheroo can take care of the correct
* suspend/resume order when changing the discrete GPU's power state. In total
* there can thus be up to three clients: Two vga clients (GPUs) and one audio
* client (on the discrete GPU). The code is mostly prepared to support
* machines with more than two GPUs should they become available.
*
* The GPU to which the outputs are currently switched is called the
* active client in vga_switcheroo parlance. The GPU not in use is the
* inactive client. When the inactive client's DRM driver is loaded,
* it will be unable to probe the panel's EDID and hence depends on
* VBIOS to provide its display modes. If the VBIOS modes are bogus or
* if there is no VBIOS at all (which is common on the MacBook Pro),
* a client may alternatively request that the DDC lines are temporarily
* switched to it, provided that the handler supports this. Switching
* only the DDC lines and not the entire output avoids unnecessary
* flickering.
*/
/**
* struct vga_switcheroo_client - registered client
* @pdev: client pci device
* @fb_info: framebuffer to which console is remapped on switching
* @pwr_state: current power state if manual power control is used.
* For driver power control, call vga_switcheroo_pwr_state().
* @ops: client callbacks
* @id: client identifier. Determining the id requires the handler,
* so gpus are initially assigned VGA_SWITCHEROO_UNKNOWN_ID
* and later given their true id in vga_switcheroo_enable()
* @active: whether the outputs are currently switched to this client
* @driver_power_control: whether power state is controlled by the driver's
* runtime pm. If true, writing ON and OFF to the vga_switcheroo debugfs
* interface is a no-op so as not to interfere with runtime pm
* @list: client list
* @vga_dev: pci device, indicate which GPU is bound to current audio client
*
* Registered client. A client can be either a GPU or an audio device on a GPU.
* For audio clients, the @fb_info and @active members are bogus. For GPU
* clients, the @vga_dev is bogus.
*/
struct vga_switcheroo_client {
struct pci_dev *pdev;
struct fb_info *fb_info;
enum vga_switcheroo_state pwr_state;
const struct vga_switcheroo_client_ops *ops;
enum vga_switcheroo_client_id id;
bool active;
bool driver_power_control;
struct list_head list;
struct pci_dev *vga_dev;
};
/*
* protects access to struct vgasr_priv
*/
static DEFINE_MUTEX(vgasr_mutex);
/**
* struct vgasr_priv - vga_switcheroo private data
* @active: whether vga_switcheroo is enabled.
* Prerequisite is the registration of two GPUs and a handler
* @delayed_switch_active: whether a delayed switch is pending
* @delayed_client_id: client to which a delayed switch is pending
* @debugfs_root: directory for vga_switcheroo debugfs interface
* @registered_clients: number of registered GPUs
* (counting only vga clients, not audio clients)
* @clients: list of registered clients
* @handler: registered handler
* @handler_flags: flags of registered handler
* @mux_hw_lock: protects mux state
* (in particular while DDC lines are temporarily switched)
* @old_ddc_owner: client to which DDC lines will be switched back on unlock
*
* vga_switcheroo private data. Currently only one vga_switcheroo instance
* per system is supported.
*/
struct vgasr_priv {
bool active;
bool delayed_switch_active;
enum vga_switcheroo_client_id delayed_client_id;
struct dentry *debugfs_root;
int registered_clients;
struct list_head clients;
const struct vga_switcheroo_handler *handler;
enum vga_switcheroo_handler_flags_t handler_flags;
struct mutex mux_hw_lock;
int old_ddc_owner;
};
#define ID_BIT_AUDIO 0x100
#define client_is_audio(c) ((c)->id & ID_BIT_AUDIO)
#define client_is_vga(c) (!client_is_audio(c))
#define client_id(c) ((c)->id & ~ID_BIT_AUDIO)
static void vga_switcheroo_debugfs_init(struct vgasr_priv *priv);
static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv);
/* only one switcheroo per system */
static struct vgasr_priv vgasr_priv = {
.clients = LIST_HEAD_INIT(vgasr_priv.clients),
.mux_hw_lock = __MUTEX_INITIALIZER(vgasr_priv.mux_hw_lock),
};
static bool vga_switcheroo_ready(void)
{
/* we're ready if we get two clients + handler */
return !vgasr_priv.active &&
vgasr_priv.registered_clients == 2 && vgasr_priv.handler;
}
static void vga_switcheroo_enable(void)
{
int ret;
struct vga_switcheroo_client *client;
/* call the handler to init */
if (vgasr_priv.handler->init)
vgasr_priv.handler->init();
list_for_each_entry(client, &vgasr_priv.clients, list) {
if (!client_is_vga(client) ||
client_id(client) != VGA_SWITCHEROO_UNKNOWN_ID)
continue;
ret = vgasr_priv.handler->get_cl
|