linux_dsm_epyc7002/sound/hda/hdac_bus.c
Takashi Iwai 88452da92b ALSA: hda: Use standard waitqueue for RIRB wakeup
The HD-audio CORB/RIRB communication was programmed in a way that was
documented in the reference in decades ago, which is essentially a
polling in the waiter side.  It's working fine but costs CPU cycles on
some platforms that support only slow communications.  Also, for some
platforms that had unreliable communications, we put longer wait time
(2 ms), which accumulate quite long time if you execute many verbs in
a shot (e.g. at the initialization or resume phase).

This patch attempts to improve the situation by introducing the
standard waitqueue in the RIRB waiter side instead of polling.  The
test results on my machine show significant improvements.  The time
spent for "cat /proc/asound/card*/codec#*" were changed like:

* Intel SKL + Realtek codec
  before the patch:
   0.00user 0.04system 0:00.10elapsed 40.0%CPU
  after the patch:
   0.00user 0.01system 0:00.10elapsed 10.0%CPU

* Nvidia GP107GL + Nvidia HDMI codec
  before the patch:
   0.00user 0.00system 0:02.76elapsed 0.0%CPU
  after the patch:
   0.00user 0.00system 0:00.01elapsed 17.0%CPU

So, for Intel chips, the total time is same, while the total time is
greatly reduced (from 2.76 to 0.01s) for Nvidia chips.
The only negative data here is the increase of CPU time for Nvidia,
but this is the unavoidable cost for faster wakeups, supposedly.

Link: https://lore.kernel.org/r/20191210145727.22054-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2019-12-10 18:22:46 +01:00

250 lines
6.4 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* HD-audio core bus driver
*/
#include <linux/init.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/export.h>
#include <sound/hdaudio.h>
#include "local.h"
#include "trace.h"
static void snd_hdac_bus_process_unsol_events(struct work_struct *work);
static const struct hdac_bus_ops default_ops = {
.command = snd_hdac_bus_send_cmd,
.get_response = snd_hdac_bus_get_response,
};
/**
* snd_hdac_bus_init - initialize a HD-audio bas bus
* @bus: the pointer to bus object
* @ops: bus verb operators
*
* Returns 0 if successful, or a negative error code.
*/
int snd_hdac_bus_init(struct hdac_bus *bus, struct device *dev,
const struct hdac_bus_ops *ops)
{
memset(bus, 0, sizeof(*bus));
bus->dev = dev;
if (ops)
bus->ops = ops;
else
bus->ops = &default_ops;
bus->dma_type = SNDRV_DMA_TYPE_DEV;
INIT_LIST_HEAD(&bus->stream_list);
INIT_LIST_HEAD(&bus->codec_list);
INIT_WORK(&bus->unsol_work, snd_hdac_bus_process_unsol_events);
spin_lock_init(&bus->reg_lock);
mutex_init(&bus->cmd_mutex);
mutex_init(&bus->lock);
INIT_LIST_HEAD(&bus->hlink_list);
init_waitqueue_head(&bus->rirb_wq);
bus->irq = -1;
return 0;
}
EXPORT_SYMBOL_GPL(snd_hdac_bus_init);
/**
* snd_hdac_bus_exit - clean up a HD-audio bas bus
* @bus: the pointer to bus object
*/
void snd_hdac_bus_exit(struct hdac_bus *bus)
{
WARN_ON(!list_empty(&bus->stream_list));
WARN_ON(!list_empty(&bus->codec_list));
cancel_work_sync(&bus->unsol_work);
}
EXPORT_SYMBOL_GPL(snd_hdac_bus_exit);
/**
* snd_hdac_bus_exec_verb - execute a HD-audio verb on the given bus
* @bus: bus object
* @cmd: HD-audio encoded verb
* @res: pointer to store the response, NULL if performing asynchronously
*
* Returns 0 if successful, or a negative error code.
*/
int snd_hdac_bus_exec_verb(struct hdac_bus *bus, unsigned int addr,
unsigned int cmd, unsigned int *res)
{
int err;
mutex_lock(&bus->cmd_mutex);
err = snd_hdac_bus_exec_verb_unlocked(bus, addr, cmd, res);
mutex_unlock(&bus->cmd_mutex);
return err;
}
EXPORT_SYMBOL_GPL(snd_hdac_bus_exec_verb);
/**
* snd_hdac_bus_exec_verb_unlocked - unlocked version
* @bus: bus object
* @cmd: HD-audio encoded verb
* @res: pointer to store the response, NULL if performing asynchronously
*
* Returns 0 if successful, or a negative error code.
*/
int snd_hdac_bus_exec_verb_unlocked(struct hdac_bus *bus, unsigned int addr,
unsigned int cmd, unsigned int *res)
{
unsigned int tmp;
int err;
if (cmd == ~0)
return -EINVAL;
if (res)
*res = -1;
else if (bus->sync_write)
res = &tmp;
for (;;) {
trace_hda_send_cmd(bus, cmd);
err = bus->ops->command(bus, cmd);
if (err != -EAGAIN)
break;
/* process pending verbs */
err = bus->ops->get_response(bus, addr, &tmp);
if (err)
break;
}
if (!err && res) {
err = bus->ops->get_response(bus, addr, res);
trace_hda_get_response(bus, addr, *res);
}
return err;
}
EXPORT_SYMBOL_GPL(snd_hdac_bus_exec_verb_unlocked);
/**
* snd_hdac_bus_queue_event - add an unsolicited event to queue
* @bus: the BUS
* @res: unsolicited event (lower 32bit of RIRB entry)
* @res_ex: codec addr and flags (upper 32bit or RIRB entry)
*
* Adds the given event to the queue. The events are processed in
* the workqueue asynchronously. Call this function in the interrupt
* hanlder when RIRB receives an unsolicited event.
*/
void snd_hdac_bus_queue_event(struct hdac_bus *bus, u32 res, u32 res_ex)
{
unsigned int wp;
if (!bus)
return;
trace_hda_unsol_event(bus, res, res_ex);
wp = (bus->unsol_wp + 1) % HDA_UNSOL_QUEUE_SIZE;
bus->unsol_wp = wp;
wp <<= 1;
bus->unsol_queue[wp] = res;
bus->unsol_queue[wp + 1] = res_ex;
schedule_work(&bus->unsol_work);
}
EXPORT_SYMBOL_GPL(snd_hdac_bus_queue_event);
/*
* process queued unsolicited events
*/
static void snd_hdac_bus_process_unsol_events(struct work_struct *work)
{
struct hdac_bus *bus = container_of(work, struct hdac_bus, unsol_work);
struct hdac_device *codec;
struct hdac_driver *drv;
unsigned int rp, caddr, res;
while (bus->unsol_rp != bus->unsol_wp) {
rp = (bus->unsol_rp + 1) % HDA_UNSOL_QUEUE_SIZE;
bus->unsol_rp = rp;
rp <<= 1;
res = bus->unsol_queue[rp];
caddr = bus->unsol_queue[rp + 1];
if (!(caddr & (1 << 4))) /* no unsolicited event? */
continue;
codec = bus->caddr_tbl[caddr & 0x0f];
if (!codec || !codec->dev.driver)
continue;
drv = drv_to_hdac_driver(codec->dev.driver);
if (drv->unsol_event)
drv->unsol_event(codec, res);
}
}
/**
* snd_hdac_bus_add_device - Add a codec to bus
* @bus: HDA core bus
* @codec: HDA core device to add
*
* Adds the given codec to the list in the bus. The caddr_tbl array
* and codec_powered bits are updated, as well.
* Returns zero if success, or a negative error code.
*/
int snd_hdac_bus_add_device(struct hdac_bus *bus, struct hdac_device *codec)
{
if (bus->caddr_tbl[codec->addr]) {
dev_err(bus->dev, "address 0x%x is already occupied\n",
codec->addr);
return -EBUSY;
}
list_add_tail(&codec->list, &bus->codec_list);
bus->caddr_tbl[codec->addr] = codec;
set_bit(codec->addr, &bus->codec_powered);
bus->num_codecs++;
return 0;
}
/**
* snd_hdac_bus_remove_device - Remove a codec from bus
* @bus: HDA core bus
* @codec: HDA core device to remove
*/
void snd_hdac_bus_remove_device(struct hdac_bus *bus,
struct hdac_device *codec)
{
WARN_ON(bus != codec->bus);
if (list_empty(&codec->list))
return;
list_del_init(&codec->list);
bus->caddr_tbl[codec->addr] = NULL;
clear_bit(codec->addr, &bus->codec_powered);
bus->num_codecs--;
flush_work(&bus->unsol_work);
}
#ifdef CONFIG_SND_HDA_ALIGNED_MMIO
/* Helpers for aligned read/write of mmio space, for Tegra */
unsigned int snd_hdac_aligned_read(void __iomem *addr, unsigned int mask)
{
void __iomem *aligned_addr =
(void __iomem *)((unsigned long)(addr) & ~0x3);
unsigned int shift = ((unsigned long)(addr) & 0x3) << 3;
unsigned int v;
v = readl(aligned_addr);
return (v >> shift) & mask;
}
EXPORT_SYMBOL_GPL(snd_hdac_aligned_read);
void snd_hdac_aligned_write(unsigned int val, void __iomem *addr,
unsigned int mask)
{
void __iomem *aligned_addr =
(void __iomem *)((unsigned long)(addr) & ~0x3);
unsigned int shift = ((unsigned long)(addr) & 0x3) << 3;
unsigned int v;
v = readl(aligned_addr);
v &= ~(mask << shift);
v |= val << shift;
writel(v, aligned_addr);
}
EXPORT_SYMBOL_GPL(snd_hdac_aligned_write);
#endif /* CONFIG_SND_HDA_ALIGNED_MMIO */