linux/sound/hda/hdac_i915.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  hdac_i915.c - routines for sync between HD-A core and i915 display driver
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <sound/core.h>
#include <sound/hdaudio.h>
#include <sound/hda_i915.h>
#include <sound/hda_register.h>
#include <video/nomodeset.h>

static int gpu_bind = …;
module_param(gpu_bind, int, 0644);
MODULE_PARM_DESC(…) …;

/**
 * snd_hdac_i915_set_bclk - Reprogram BCLK for HSW/BDW
 * @bus: HDA core bus
 *
 * Intel HSW/BDW display HDA controller is in GPU. Both its power and link BCLK
 * depends on GPU. Two Extended Mode registers EM4 (M value) and EM5 (N Value)
 * are used to convert CDClk (Core Display Clock) to 24MHz BCLK:
 * BCLK = CDCLK * M / N
 * The values will be lost when the display power well is disabled and need to
 * be restored to avoid abnormal playback speed.
 *
 * Call this function at initializing and changing power well, as well as
 * at ELD notifier for the hotplug.
 */
void snd_hdac_i915_set_bclk(struct hdac_bus *bus)
{ … }
EXPORT_SYMBOL_GPL(…);

/* returns true if the devices can be connected for audio */
static bool connectivity_check(struct pci_dev *i915, struct pci_dev *hdac)
{ … }

static int i915_component_master_match(struct device *dev, int subcomponent,
				       void *data)
{ … }

/* check whether Intel graphics is present and reachable */
static int i915_gfx_present(struct pci_dev *hdac_pci)
{ … }

/**
 * snd_hdac_i915_init - Initialize i915 audio component
 * @bus: HDA core bus
 *
 * This function is supposed to be used only by a HD-audio controller
 * driver that needs the interaction with i915 graphics.
 *
 * This function initializes and sets up the audio component to communicate
 * with i915 graphics driver.
 *
 * Returns zero for success or a negative error code.
 */
int snd_hdac_i915_init(struct hdac_bus *bus)
{ … }
EXPORT_SYMBOL_GPL(…);