linux/drivers/gpu/drm/drm_stub.c
Mario Kleiner 27641c3f00 drm/vblank: Add support for precise vblank timestamping.
The DRI2 swap & sync implementation needs precise
vblank counts and precise timestamps corresponding
to those vblank counts. For conformance to the OpenML
OML_sync_control extension specification the DRM
timestamp associated with a vblank count should
correspond to the start of video scanout of the first
scanline of the video frame following the vblank
interval for that vblank count.

Therefore we need to carry around precise timestamps
for vblanks. Currently the DRM and KMS drivers generate
timestamps ad-hoc via do_gettimeofday() in some
places. The resulting timestamps are sometimes not
very precise due to interrupt handling delays, they
don't conform to OML_sync_control and some are wrong,
as they aren't taken synchronized to the vblank.

This patch implements support inside the drm core
for precise and robust timestamping. It consists
of the following interrelated pieces.

1. Vblank timestamp caching:

A per-crtc ringbuffer stores the most recent vblank
timestamps corresponding to vblank counts.

The ringbuffer can be read out lock-free via the
accessor function:

struct timeval timestamp;
vblankcount = drm_vblank_count_and_time(dev, crtcid, &timestamp).

The function returns the current vblank count and
the corresponding timestamp for start of video
scanout following the vblank interval. It can be
used anywhere between enclosing drm_vblank_get(dev, crtcid)
and drm_vblank_put(dev,crtcid) statements. It is used
inside the drmWaitVblank ioctl and in the vblank event
queueing and handling. It should be used by kms drivers for
timestamping of bufferswap completion.

The timestamp ringbuffer is reinitialized each time
vblank irq's get reenabled in drm_vblank_get()/
drm_update_vblank_count(). It is invalidated when
vblank irq's get disabled.

The ringbuffer is updated inside drm_handle_vblank()
at each vblank irq.

2. Calculation of precise vblank timestamps:

drm_get_last_vbltimestamp() is used to compute the
timestamp for the end of the most recent vblank (if
inside active scanout), or the expected end of the
current vblank interval (if called inside a vblank
interval). The function calls into a new optional kms
driver entry point dev->driver->get_vblank_timestamp()
which is supposed to provide the precise timestamp.
If a kms driver doesn't implement the entry point or
if the call fails, a simple do_gettimeofday() timestamp
is returned as crude approximation of the true vblank time.

A new drm module parameter drm.timestamp_precision_usec
allows to disable high precision timestamps (if set to
zero) or to specify the maximum acceptable error in
the timestamps in microseconds.

Kms drivers could implement their get_vblank_timestamp()
function in a gpu specific way, as long as returned
timestamps conform to OML_sync_control, e.g., by use
of gpu specific hardware timestamps.

Optionally, kms drivers can simply wrap and use the new
utility function drm_calc_vbltimestamp_from_scanoutpos().
This function calls a new optional kms driver function
dev->driver->get_scanout_position() which returns the
current horizontal and vertical video scanout position
of the crtc. The scanout position together with the
drm_display_timing of the current video mode is used
to calculate elapsed time relative to start of active scanout
for the current video frame. This elapsed time is subtracted
from the current do_gettimeofday() time to get the timestamp
corresponding to start of video scanout. Currently
non-interlaced, non-doublescan video modes, with or
without panel scaling are handled correctly. Interlaced/
doublescan modes are tbd in a future patch.

3. Filtering of redundant vblank irq's and removal of
some race-conditions in the vblank irq enable/disable path:

Some gpu's (e.g., Radeon R500/R600) send spurious vblank
irq's outside the vblank if vblank irq's get reenabled.
These get detected by use of the vblank timestamps and
filtered out to avoid miscounting of vblanks.

Some race-conditions between the vblank irq enable/disable
functions, the vblank irq handler and the gpu itself (updating
its hardware vblank counter in the "wrong" moment) are
fixed inside vblank_disable_and_save() and
drm_update_vblank_count() by use of the vblank timestamps and
a new spinlock dev->vblank_time_lock.

The time until vblank irq disable is now configurable via
a new drm module parameter drm.vblankoffdelay to allow
experimentation with timeouts that are much shorter than
the current 5 seconds and should allow longer vblank off
periods for better power savings.

Followup patches will use these new functions to
implement precise timestamping for the intel and radeon
kms drivers.

Signed-off-by: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2010-11-22 11:45:05 +10:00

485 lines
12 KiB
C

/**
* \file drm_stub.h
* Stub support
*
* \author Rickard E. (Rik) Faith <faith@valinux.com>
*/
/*
* Created: Fri Jan 19 10:48:35 2001 by faith@acm.org
*
* Copyright 2001 VA Linux Systems, Inc., Sunnyvale, California.
* All Rights Reserved.
*
* 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
* PRECISION INSIGHT AND/OR ITS SUPPLIERS 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.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include "drmP.h"
#include "drm_core.h"
unsigned int drm_debug = 0; /* 1 to enable debug output */
EXPORT_SYMBOL(drm_debug);
unsigned int drm_vblank_offdelay = 5000; /* Default to 5000 msecs. */
EXPORT_SYMBOL(drm_vblank_offdelay);
unsigned int drm_timestamp_precision = 20; /* Default to 20 usecs. */
EXPORT_SYMBOL(drm_timestamp_precision);
MODULE_AUTHOR(CORE_AUTHOR);
MODULE_DESCRIPTION(CORE_DESC);
MODULE_LICENSE("GPL and additional rights");
MODULE_PARM_DESC(debug, "Enable debug output");
MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]");
MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
module_param_named(debug, drm_debug, int, 0600);
module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
struct idr drm_minors_idr;
struct class *drm_class;
struct proc_dir_entry *drm_proc_root;
struct dentry *drm_debugfs_root;
void drm_ut_debug_printk(unsigned int request_level,
const char *prefix,
const char *function_name,
const char *format, ...)
{
va_list args;
if (drm_debug & request_level) {
if (function_name)
printk(KERN_DEBUG "[%s:%s], ", prefix, function_name);
va_start(args, format);
vprintk(format, args);
va_end(args);
}
}
EXPORT_SYMBOL(drm_ut_debug_printk);
static int drm_minor_get_id(struct drm_device *dev, int type)
{
int new_id;
int ret;
int base = 0, limit = 63;
if (type == DRM_MINOR_CONTROL) {
base += 64;
limit = base + 127;
} else if (type == DRM_MINOR_RENDER) {
base += 128;
limit = base + 255;
}
again:
if (idr_pre_get(&drm_minors_idr, GFP_KERNEL) == 0) {
DRM_ERROR("Out of memory expanding drawable idr\n");
return -ENOMEM;
}
mutex_lock(&dev->struct_mutex);
ret = idr_get_new_above(&drm_minors_idr, NULL,
base, &new_id);
mutex_unlock(&dev->struct_mutex);
if (ret == -EAGAIN) {
goto again;
} else if (ret) {
return ret;
}
if (new_id >= limit) {
idr_remove(&drm_minors_idr, new_id);
return -EINVAL;
}
return new_id;
}
struct drm_master *drm_master_create(struct drm_minor *minor)
{
struct drm_master *master;
master = kzalloc(sizeof(*master), GFP_KERNEL);
if (!master)
return NULL;
kref_init(&master->refcount);
spin_lock_init(&master->lock.spinlock);
init_waitqueue_head(&master->lock.lock_queue);
drm_ht_create(&master->magiclist, DRM_MAGIC_HASH_ORDER);
INIT_LIST_HEAD(&master->magicfree);
master->minor = minor;
list_add_tail(&master->head, &minor->master_list);
return master;
}
struct drm_master *drm_master_get(struct drm_master *master)
{
kref_get(&master->refcount);
return master;
}
EXPORT_SYMBOL(drm_master_get);
static void drm_master_destroy(struct kref *kref)
{
struct drm_master *master = container_of(kref, struct drm_master, refcount);
struct drm_magic_entry *pt, *next;
struct drm_device *dev = master->minor->dev;
struct drm_map_list *r_list, *list_temp;
list_del(&master->head);
if (dev->driver->master_destroy)
dev->driver->master_destroy(dev, master);
list_for_each_entry_safe(r_list, list_temp, &dev->maplist, head) {
if (r_list->master == master) {
drm_rmmap_locked(dev, r_list->map);
r_list = NULL;
}
}
if (master->unique) {
kfree(master->unique);
master->unique = NULL;
master->unique_len = 0;
}
kfree(dev->devname);
dev->devname = NULL;
list_for_each_entry_safe(pt, next, &master->magicfree, head) {
list_del(&pt->head);
drm_ht_remove_item(&master->magiclist, &pt->hash_item);
kfree(pt);
}
drm_ht_remove(&master->magiclist);
kfree(master);
}
void drm_master_put(struct drm_master **master)
{
kref_put(&(*master)->refcount, drm_master_destroy);
*master = NULL;
}
EXPORT_SYMBOL(drm_master_put);
int drm_setmaster_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
int ret = 0;
if (file_priv->is_master)
return 0;
if (file_priv->minor->master && file_priv->minor->master != file_priv->master)
return -EINVAL;
if (!file_priv->master)
return -EINVAL;
if (!file_priv->minor->master &&
file_priv->minor->master != file_priv->master) {
mutex_lock(&dev->struct_mutex);
file_priv->minor->master = drm_master_get(file_priv->master);
file_priv->is_master = 1;
if (dev->driver->master_set) {
ret = dev->driver->master_set(dev, file_priv, false);
if (unlikely(ret != 0)) {
file_priv->is_master = 0;
drm_master_put(&file_priv->minor->master);
}
}
mutex_unlock(&dev->struct_mutex);
}
return 0;
}
int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
struct drm_file *file_priv)
{
if (!file_priv->is_master)
return -EINVAL;
if (!file_priv->minor->master)
return -EINVAL;
mutex_lock(&dev->struct_mutex);
if (dev->driver->master_drop)
dev->driver->master_drop(dev, file_priv, false);
drm_master_put(&file_priv->minor->master);
file_priv->is_master = 0;
mutex_unlock(&dev->struct_mutex);
return 0;
}
int drm_fill_in_dev(struct drm_device *dev,
const struct pci_device_id *ent,
struct drm_driver *driver)
{
int retcode;
INIT_LIST_HEAD(&dev->filelist);
INIT_LIST_HEAD(&dev->ctxlist);
INIT_LIST_HEAD(&dev->vmalist);
INIT_LIST_HEAD(&dev->maplist);
INIT_LIST_HEAD(&dev->vblank_event_list);
spin_lock_init(&dev->count_lock);
spin_lock_init(&dev->event_lock);
mutex_init(&dev->struct_mutex);
mutex_init(&dev->ctxlist_mutex);
if (drm_ht_create(&dev->map_hash, 12)) {
return -ENOMEM;
}
/* the DRM has 6 basic counters */
dev->counters = 6;
dev->types[0] = _DRM_STAT_LOCK;
dev->types[1] = _DRM_STAT_OPENS;
dev->types[2] = _DRM_STAT_CLOSES;
dev->types[3] = _DRM_STAT_IOCTLS;
dev->types[4] = _DRM_STAT_LOCKS;
dev->types[5] = _DRM_STAT_UNLOCKS;
dev->driver = driver;
if (drm_core_has_AGP(dev)) {
if (drm_device_is_agp(dev))
dev->agp = drm_agp_init(dev);
if (drm_core_check_feature(dev, DRIVER_REQUIRE_AGP)
&& (dev->agp == NULL)) {
DRM_ERROR("Cannot initialize the agpgart module.\n");
retcode = -EINVAL;
goto error_out_unreg;
}
if (drm_core_has_MTRR(dev)) {
if (dev->agp)
dev->agp->agp_mtrr =
mtrr_add(dev->agp->agp_info.aper_base,
dev->agp->agp_info.aper_size *
1024 * 1024, MTRR_TYPE_WRCOMB, 1);
}
}
retcode = drm_ctxbitmap_init(dev);
if (retcode) {
DRM_ERROR("Cannot allocate memory for context bitmap.\n");
goto error_out_unreg;
}
if (driver->driver_features & DRIVER_GEM) {
retcode = drm_gem_init(dev);
if (retcode) {
DRM_ERROR("Cannot initialize graphics execution "
"manager (GEM)\n");
goto error_out_unreg;
}
}
return 0;
error_out_unreg:
drm_lastclose(dev);
return retcode;
}
/**
* Get a secondary minor number.
*
* \param dev device data structure
* \param sec-minor structure to hold the assigned minor
* \return negative number on failure.
*
* Search an empty entry and initialize it to the given parameters, and
* create the proc init entry via proc_init(). This routines assigns
* minor numbers to secondary heads of multi-headed cards
*/
int drm_get_minor(struct drm_device *dev, struct drm_minor **minor, int type)
{
struct drm_minor *new_minor;
int ret;
int minor_id;
DRM_DEBUG("\n");
minor_id = drm_minor_get_id(dev, type);
if (minor_id < 0)
return minor_id;
new_minor = kzalloc(sizeof(struct drm_minor), GFP_KERNEL);
if (!new_minor) {
ret = -ENOMEM;
goto err_idr;
}
new_minor->type = type;
new_minor->device = MKDEV(DRM_MAJOR, minor_id);
new_minor->dev = dev;
new_minor->index = minor_id;
INIT_LIST_HEAD(&new_minor->master_list);
idr_replace(&drm_minors_idr, new_minor, minor_id);
if (type == DRM_MINOR_LEGACY) {
ret = drm_proc_init(new_minor, minor_id, drm_proc_root);
if (ret) {
DRM_ERROR("DRM: Failed to initialize /proc/dri.\n");
goto err_mem;
}
} else
new_minor->proc_root = NULL;
#if defined(CONFIG_DEBUG_FS)
ret = drm_debugfs_init(new_minor, minor_id, drm_debugfs_root);
if (ret) {
DRM_ERROR("DRM: Failed to initialize /sys/kernel/debug/dri.\n");
goto err_g2;
}
#endif
ret = drm_sysfs_device_add(new_minor);
if (ret) {
printk(KERN_ERR
"DRM: Error sysfs_device_add.\n");
goto err_g2;
}
*minor = new_minor;
DRM_DEBUG("new minor assigned %d\n", minor_id);
return 0;
err_g2:
if (new_minor->type == DRM_MINOR_LEGACY)
drm_proc_cleanup(new_minor, drm_proc_root);
err_mem:
kfree(new_minor);
err_idr:
idr_remove(&drm_minors_idr, minor_id);
*minor = NULL;
return ret;
}
/**
* Put a secondary minor number.
*
* \param sec_minor - structure to be released
* \return always zero
*
* Cleans up the proc resources. Not legal for this to be the
* last minor released.
*
*/
int drm_put_minor(struct drm_minor **minor_p)
{
struct drm_minor *minor = *minor_p;
DRM_DEBUG("release secondary minor %d\n", minor->index);
if (minor->type == DRM_MINOR_LEGACY)
drm_proc_cleanup(minor, drm_proc_root);
#if defined(CONFIG_DEBUG_FS)
drm_debugfs_cleanup(minor);
#endif
drm_sysfs_device_remove(minor);
idr_remove(&drm_minors_idr, minor->index);
kfree(minor);
*minor_p = NULL;
return 0;
}
/**
* Called via drm_exit() at module unload time or when pci device is
* unplugged.
*
* Cleans up all DRM device, calling drm_lastclose().
*
* \sa drm_init
*/
void drm_put_dev(struct drm_device *dev)
{
struct drm_driver *driver;
struct drm_map_list *r_list, *list_temp;
DRM_DEBUG("\n");
if (!dev) {
DRM_ERROR("cleanup called no dev\n");
return;
}
driver = dev->driver;
drm_lastclose(dev);
if (drm_core_has_MTRR(dev) && drm_core_has_AGP(dev) &&
dev->agp && dev->agp->agp_mtrr >= 0) {
int retval;
retval = mtrr_del(dev->agp->agp_mtrr,
dev->agp->agp_info.aper_base,
dev->agp->agp_info.aper_size * 1024 * 1024);
DRM_DEBUG("mtrr_del=%d\n", retval);
}
if (dev->driver->unload)
dev->driver->unload(dev);
if (drm_core_has_AGP(dev) && dev->agp) {
kfree(dev->agp);
dev->agp = NULL;
}
drm_vblank_cleanup(dev);
list_for_each_entry_safe(r_list, list_temp, &dev->maplist, head)
drm_rmmap(dev, r_list->map);
drm_ht_remove(&dev->map_hash);
drm_ctxbitmap_cleanup(dev);
if (drm_core_check_feature(dev, DRIVER_MODESET))
drm_put_minor(&dev->control);
if (driver->driver_features & DRIVER_GEM)
drm_gem_destroy(dev);
drm_put_minor(&dev->primary);
if (dev->devname) {
kfree(dev->devname);
dev->devname = NULL;
}
kfree(dev);
}
EXPORT_SYMBOL(drm_put_dev);