linux/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
Nirmoy Das 0b17fc08e3 drm/vmwgfx: don't use ttm bo->offset
Calculate GPU offset within vmwgfx driver itself without depending on
bo->offset.

Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/372933/
Signed-off-by: Christian König <christian.koenig@amd.com>
2020-06-26 14:00:41 +02:00

692 lines
19 KiB
C

// SPDX-License-Identifier: GPL-2.0 OR MIT
/**************************************************************************
*
* Copyright 2009-2015 VMware, Inc., Palo Alto, CA., USA
*
* 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS, AUTHORS 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/sched/signal.h>
#include <drm/ttm/ttm_placement.h>
#include "vmwgfx_drv.h"
struct vmw_temp_set_context {
SVGA3dCmdHeader header;
SVGA3dCmdDXTempSetContext body;
};
bool vmw_fifo_have_3d(struct vmw_private *dev_priv)
{
u32 *fifo_mem = dev_priv->mmio_virt;
uint32_t fifo_min, hwversion;
const struct vmw_fifo_state *fifo = &dev_priv->fifo;
if (!(dev_priv->capabilities & SVGA_CAP_3D))
return false;
if (dev_priv->capabilities & SVGA_CAP_GBOBJECTS) {
uint32_t result;
if (!dev_priv->has_mob)
return false;
spin_lock(&dev_priv->cap_lock);
vmw_write(dev_priv, SVGA_REG_DEV_CAP, SVGA3D_DEVCAP_3D);
result = vmw_read(dev_priv, SVGA_REG_DEV_CAP);
spin_unlock(&dev_priv->cap_lock);
return (result != 0);
}
if (!(dev_priv->capabilities & SVGA_CAP_EXTENDED_FIFO))
return false;
fifo_min = vmw_mmio_read(fifo_mem + SVGA_FIFO_MIN);
if (fifo_min <= SVGA_FIFO_3D_HWVERSION * sizeof(unsigned int))
return false;
hwversion = vmw_mmio_read(fifo_mem +
((fifo->capabilities &
SVGA_FIFO_CAP_3D_HWVERSION_REVISED) ?
SVGA_FIFO_3D_HWVERSION_REVISED :
SVGA_FIFO_3D_HWVERSION));
if (hwversion == 0)
return false;
if (hwversion < SVGA3D_HWVERSION_WS8_B1)
return false;
/* Legacy Display Unit does not support surfaces */
if (dev_priv->active_display_unit == vmw_du_legacy)
return false;
return true;
}
bool vmw_fifo_have_pitchlock(struct vmw_private *dev_priv)
{
u32 *fifo_mem = dev_priv->mmio_virt;
uint32_t caps;
if (!(dev_priv->capabilities & SVGA_CAP_EXTENDED_FIFO))
return false;
caps = vmw_mmio_read(fifo_mem + SVGA_FIFO_CAPABILITIES);
if (caps & SVGA_FIFO_CAP_PITCHLOCK)
return true;
return false;
}
int vmw_fifo_init(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
{
u32 *fifo_mem = dev_priv->mmio_virt;
uint32_t max;
uint32_t min;
fifo->dx = false;
fifo->static_buffer_size = VMWGFX_FIFO_STATIC_SIZE;
fifo->static_buffer = vmalloc(fifo->static_buffer_size);
if (unlikely(fifo->static_buffer == NULL))
return -ENOMEM;
fifo->dynamic_buffer = NULL;
fifo->reserved_size = 0;
fifo->using_bounce_buffer = false;
mutex_init(&fifo->fifo_mutex);
init_rwsem(&fifo->rwsem);
DRM_INFO("width %d\n", vmw_read(dev_priv, SVGA_REG_WIDTH));
DRM_INFO("height %d\n", vmw_read(dev_priv, SVGA_REG_HEIGHT));
DRM_INFO("bpp %d\n", vmw_read(dev_priv, SVGA_REG_BITS_PER_PIXEL));
dev_priv->enable_state = vmw_read(dev_priv, SVGA_REG_ENABLE);
dev_priv->config_done_state = vmw_read(dev_priv, SVGA_REG_CONFIG_DONE);
dev_priv->traces_state = vmw_read(dev_priv, SVGA_REG_TRACES);
vmw_write(dev_priv, SVGA_REG_ENABLE, SVGA_REG_ENABLE_ENABLE |
SVGA_REG_ENABLE_HIDE);
vmw_write(dev_priv, SVGA_REG_TRACES, 0);
min = 4;
if (dev_priv->capabilities & SVGA_CAP_EXTENDED_FIFO)
min = vmw_read(dev_priv, SVGA_REG_MEM_REGS);
min <<= 2;
if (min < PAGE_SIZE)
min = PAGE_SIZE;
vmw_mmio_write(min, fifo_mem + SVGA_FIFO_MIN);
vmw_mmio_write(dev_priv->mmio_size, fifo_mem + SVGA_FIFO_MAX);
wmb();
vmw_mmio_write(min, fifo_mem + SVGA_FIFO_NEXT_CMD);
vmw_mmio_write(min, fifo_mem + SVGA_FIFO_STOP);
vmw_mmio_write(0, fifo_mem + SVGA_FIFO_BUSY);
mb();
vmw_write(dev_priv, SVGA_REG_CONFIG_DONE, 1);
max = vmw_mmio_read(fifo_mem + SVGA_FIFO_MAX);
min = vmw_mmio_read(fifo_mem + SVGA_FIFO_MIN);
fifo->capabilities = vmw_mmio_read(fifo_mem + SVGA_FIFO_CAPABILITIES);
DRM_INFO("Fifo max 0x%08x min 0x%08x cap 0x%08x\n",
(unsigned int) max,
(unsigned int) min,
(unsigned int) fifo->capabilities);
atomic_set(&dev_priv->marker_seq, dev_priv->last_read_seqno);
vmw_mmio_write(dev_priv->last_read_seqno, fifo_mem + SVGA_FIFO_FENCE);
vmw_marker_queue_init(&fifo->marker_queue);
return 0;
}
void vmw_fifo_ping_host(struct vmw_private *dev_priv, uint32_t reason)
{
u32 *fifo_mem = dev_priv->mmio_virt;
if (cmpxchg(fifo_mem + SVGA_FIFO_BUSY, 0, 1) == 0)
vmw_write(dev_priv, SVGA_REG_SYNC, reason);
}
void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
{
u32 *fifo_mem = dev_priv->mmio_virt;
vmw_write(dev_priv, SVGA_REG_SYNC, SVGA_SYNC_GENERIC);
while (vmw_read(dev_priv, SVGA_REG_BUSY) != 0)
;
dev_priv->last_read_seqno = vmw_mmio_read(fifo_mem + SVGA_FIFO_FENCE);
vmw_write(dev_priv, SVGA_REG_CONFIG_DONE,
dev_priv->config_done_state);
vmw_write(dev_priv, SVGA_REG_ENABLE,
dev_priv->enable_state);
vmw_write(dev_priv, SVGA_REG_TRACES,
dev_priv->traces_state);
vmw_marker_queue_takedown(&fifo->marker_queue);
if (likely(fifo->static_buffer != NULL)) {
vfree(fifo->static_buffer);
fifo->static_buffer = NULL;
}
if (likely(fifo->dynamic_buffer != NULL)) {
vfree(fifo->dynamic_buffer);
fifo->dynamic_buffer = NULL;
}
}
static bool vmw_fifo_is_full(struct vmw_private *dev_priv, uint32_t bytes)
{
u32 *fifo_mem = dev_priv->mmio_virt;
uint32_t max = vmw_mmio_read(fifo_mem + SVGA_FIFO_MAX);
uint32_t next_cmd = vmw_mmio_read(fifo_mem + SVGA_FIFO_NEXT_CMD);
uint32_t min = vmw_mmio_read(fifo_mem + SVGA_FIFO_MIN);
uint32_t stop = vmw_mmio_read(fifo_mem + SVGA_FIFO_STOP);
return ((max - next_cmd) + (stop - min) <= bytes);
}
static int vmw_fifo_wait_noirq(struct vmw_private *dev_priv,
uint32_t bytes, bool interruptible,
unsigned long timeout)
{
int ret = 0;
unsigned long end_jiffies = jiffies + timeout;
DEFINE_WAIT(__wait);
DRM_INFO("Fifo wait noirq.\n");
for (;;) {
prepare_to_wait(&dev_priv->fifo_queue, &__wait,
(interruptible) ?
TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
if (!vmw_fifo_is_full(dev_priv, bytes))
break;
if (time_after_eq(jiffies, end_jiffies)) {
ret = -EBUSY;
DRM_ERROR("SVGA device lockup.\n");
break;
}
schedule_timeout(1);
if (interruptible && signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
}
finish_wait(&dev_priv->fifo_queue, &__wait);
wake_up_all(&dev_priv->fifo_queue);
DRM_INFO("Fifo noirq exit.\n");
return ret;
}
static int vmw_fifo_wait(struct vmw_private *dev_priv,
uint32_t bytes, bool interruptible,
unsigned long timeout)
{
long ret = 1L;
if (likely(!vmw_fifo_is_full(dev_priv, bytes)))
return 0;
vmw_fifo_ping_host(dev_priv, SVGA_SYNC_FIFOFULL);
if (!(dev_priv->capabilities & SVGA_CAP_IRQMASK))
return vmw_fifo_wait_noirq(dev_priv, bytes,
interruptible, timeout);
vmw_generic_waiter_add(dev_priv, SVGA_IRQFLAG_FIFO_PROGRESS,
&dev_priv->fifo_queue_waiters);
if (interruptible)
ret = wait_event_interruptible_timeout
(dev_priv->fifo_queue,
!vmw_fifo_is_full(dev_priv, bytes), timeout);
else
ret = wait_event_timeout
(dev_priv->fifo_queue,
!vmw_fifo_is_full(dev_priv, bytes), timeout);
if (unlikely(ret == 0))
ret = -EBUSY;
else if (likely(ret > 0))
ret = 0;
vmw_generic_waiter_remove(dev_priv, SVGA_IRQFLAG_FIFO_PROGRESS,
&dev_priv->fifo_queue_waiters);
return ret;
}
/**
* Reserve @bytes number of bytes in the fifo.
*
* This function will return NULL (error) on two conditions:
* If it timeouts waiting for fifo space, or if @bytes is larger than the
* available fifo space.
*
* Returns:
* Pointer to the fifo, or null on error (possible hardware hang).
*/
static void *vmw_local_fifo_reserve(struct vmw_private *dev_priv,
uint32_t bytes)
{
struct vmw_fifo_state *fifo_state = &dev_priv->fifo;
u32 *fifo_mem = dev_priv->mmio_virt;
uint32_t max;
uint32_t min;
uint32_t next_cmd;
uint32_t reserveable = fifo_state->capabilities & SVGA_FIFO_CAP_RESERVE;
int ret;
mutex_lock(&fifo_state->fifo_mutex);
max = vmw_mmio_read(fifo_mem + SVGA_FIFO_MAX);
min = vmw_mmio_read(fifo_mem + SVGA_FIFO_MIN);
next_cmd = vmw_mmio_read(fifo_mem + SVGA_FIFO_NEXT_CMD);
if (unlikely(bytes >= (max - min)))
goto out_err;
BUG_ON(fifo_state->reserved_size != 0);
BUG_ON(fifo_state->dynamic_buffer != NULL);
fifo_state->reserved_size = bytes;
while (1) {
uint32_t stop = vmw_mmio_read(fifo_mem + SVGA_FIFO_STOP);
bool need_bounce = false;
bool reserve_in_place = false;
if (next_cmd >= stop) {
if (likely((next_cmd + bytes < max ||
(next_cmd + bytes == max && stop > min))))
reserve_in_place = true;
else if (vmw_fifo_is_full(dev_priv, bytes)) {
ret = vmw_fifo_wait(dev_priv, bytes,
false, 3 * HZ);
if (unlikely(ret != 0))
goto out_err;
} else
need_bounce = true;
} else {
if (likely((next_cmd + bytes < stop)))
reserve_in_place = true;
else {
ret = vmw_fifo_wait(dev_priv, bytes,
false, 3 * HZ);
if (unlikely(ret != 0))
goto out_err;
}
}
if (reserve_in_place) {
if (reserveable || bytes <= sizeof(uint32_t)) {
fifo_state->using_bounce_buffer = false;
if (reserveable)
vmw_mmio_write(bytes, fifo_mem +
SVGA_FIFO_RESERVED);
return (void __force *) (fifo_mem +
(next_cmd >> 2));
} else {
need_bounce = true;
}
}
if (need_bounce) {
fifo_state->using_bounce_buffer = true;
if (bytes < fifo_state->static_buffer_size)
return fifo_state->static_buffer;
else {
fifo_state->dynamic_buffer = vmalloc(bytes);
if (!fifo_state->dynamic_buffer)
goto out_err;
return fifo_state->dynamic_buffer;
}
}
}
out_err:
fifo_state->reserved_size = 0;
mutex_unlock(&fifo_state->fifo_mutex);
return NULL;
}
void *vmw_fifo_reserve_dx(struct vmw_private *dev_priv, uint32_t bytes,
int ctx_id)
{
void *ret;
if (dev_priv->cman)
ret = vmw_cmdbuf_reserve(dev_priv->cman, bytes,
ctx_id, false, NULL);
else if (ctx_id == SVGA3D_INVALID_ID)
ret = vmw_local_fifo_reserve(dev_priv, bytes);
else {
WARN(1, "Command buffer has not been allocated.\n");
ret = NULL;
}
if (IS_ERR_OR_NULL(ret))
return NULL;
return ret;
}
static void vmw_fifo_res_copy(struct vmw_fifo_state *fifo_state,
u32 *fifo_mem,
uint32_t next_cmd,
uint32_t max, uint32_t min, uint32_t bytes)
{
uint32_t chunk_size = max - next_cmd;
uint32_t rest;
uint32_t *buffer = (fifo_state->dynamic_buffer != NULL) ?
fifo_state->dynamic_buffer : fifo_state->static_buffer;
if (bytes < chunk_size)
chunk_size = bytes;
vmw_mmio_write(bytes, fifo_mem + SVGA_FIFO_RESERVED);
mb();
memcpy(fifo_mem + (next_cmd >> 2), buffer, chunk_size);
rest = bytes - chunk_size;
if (rest)
memcpy(fifo_mem + (min >> 2), buffer + (chunk_size >> 2), rest);
}
static void vmw_fifo_slow_copy(struct vmw_fifo_state *fifo_state,
u32 *fifo_mem,
uint32_t next_cmd,
uint32_t max, uint32_t min, uint32_t bytes)
{
uint32_t *buffer = (fifo_state->dynamic_buffer != NULL) ?
fifo_state->dynamic_buffer : fifo_state->static_buffer;
while (bytes > 0) {
vmw_mmio_write(*buffer++, fifo_mem + (next_cmd >> 2));
next_cmd += sizeof(uint32_t);
if (unlikely(next_cmd == max))
next_cmd = min;
mb();
vmw_mmio_write(next_cmd, fifo_mem + SVGA_FIFO_NEXT_CMD);
mb();
bytes -= sizeof(uint32_t);
}
}
static void vmw_local_fifo_commit(struct vmw_private *dev_priv, uint32_t bytes)
{
struct vmw_fifo_state *fifo_state = &dev_priv->fifo;
u32 *fifo_mem = dev_priv->mmio_virt;
uint32_t next_cmd = vmw_mmio_read(fifo_mem + SVGA_FIFO_NEXT_CMD);
uint32_t max = vmw_mmio_read(fifo_mem + SVGA_FIFO_MAX);
uint32_t min = vmw_mmio_read(fifo_mem + SVGA_FIFO_MIN);
bool reserveable = fifo_state->capabilities & SVGA_FIFO_CAP_RESERVE;
if (fifo_state->dx)
bytes += sizeof(struct vmw_temp_set_context);
fifo_state->dx = false;
BUG_ON((bytes & 3) != 0);
BUG_ON(bytes > fifo_state->reserved_size);
fifo_state->reserved_size = 0;
if (fifo_state->using_bounce_buffer) {
if (reserveable)
vmw_fifo_res_copy(fifo_state, fifo_mem,
next_cmd, max, min, bytes);
else
vmw_fifo_slow_copy(fifo_state, fifo_mem,
next_cmd, max, min, bytes);
if (fifo_state->dynamic_buffer) {
vfree(fifo_state->dynamic_buffer);
fifo_state->dynamic_buffer = NULL;
}
}
down_write(&fifo_state->rwsem);
if (fifo_state->using_bounce_buffer || reserveable) {
next_cmd += bytes;
if (next_cmd >= max)
next_cmd -= max - min;
mb();
vmw_mmio_write(next_cmd, fifo_mem + SVGA_FIFO_NEXT_CMD);
}
if (reserveable)
vmw_mmio_write(0, fifo_mem + SVGA_FIFO_RESERVED);
mb();
up_write(&fifo_state->rwsem);
vmw_fifo_ping_host(dev_priv, SVGA_SYNC_GENERIC);
mutex_unlock(&fifo_state->fifo_mutex);
}
void vmw_fifo_commit(struct vmw_private *dev_priv, uint32_t bytes)
{
if (dev_priv->cman)
vmw_cmdbuf_commit(dev_priv->cman, bytes, NULL, false);
else
vmw_local_fifo_commit(dev_priv, bytes);
}
/**
* vmw_fifo_commit_flush - Commit fifo space and flush any buffered commands.
*
* @dev_priv: Pointer to device private structure.
* @bytes: Number of bytes to commit.
*/
void vmw_fifo_commit_flush(struct vmw_private *dev_priv, uint32_t bytes)
{
if (dev_priv->cman)
vmw_cmdbuf_commit(dev_priv->cman, bytes, NULL, true);
else
vmw_local_fifo_commit(dev_priv, bytes);
}
/**
* vmw_fifo_flush - Flush any buffered commands and make sure command processing
* starts.
*
* @dev_priv: Pointer to device private structure.
* @interruptible: Whether to wait interruptible if function needs to sleep.
*/
int vmw_fifo_flush(struct vmw_private *dev_priv, bool interruptible)
{
might_sleep();
if (dev_priv->cman)
return vmw_cmdbuf_cur_flush(dev_priv->cman, interruptible);
else
return 0;
}
int vmw_fifo_send_fence(struct vmw_private *dev_priv, uint32_t *seqno)
{
struct vmw_fifo_state *fifo_state = &dev_priv->fifo;
struct svga_fifo_cmd_fence *cmd_fence;
u32 *fm;
int ret = 0;
uint32_t bytes = sizeof(u32) + sizeof(*cmd_fence);
fm = VMW_FIFO_RESERVE(dev_priv, bytes);
if (unlikely(fm == NULL)) {
*seqno = atomic_read(&dev_priv->marker_seq);
ret = -ENOMEM;
(void)vmw_fallback_wait(dev_priv, false, true, *seqno,
false, 3*HZ);
goto out_err;
}
do {
*seqno = atomic_add_return(1, &dev_priv->marker_seq);
} while (*seqno == 0);
if (!(fifo_state->capabilities & SVGA_FIFO_CAP_FENCE)) {
/*
* Don't request hardware to send a fence. The
* waiting code in vmwgfx_irq.c will emulate this.
*/
vmw_fifo_commit(dev_priv, 0);
return 0;
}
*fm++ = SVGA_CMD_FENCE;
cmd_fence = (struct svga_fifo_cmd_fence *) fm;
cmd_fence->fence = *seqno;
vmw_fifo_commit_flush(dev_priv, bytes);
(void) vmw_marker_push(&fifo_state->marker_queue, *seqno);
vmw_update_seqno(dev_priv, fifo_state);
out_err:
return ret;
}
/**
* vmw_fifo_emit_dummy_legacy_query - emits a dummy query to the fifo using
* legacy query commands.
*
* @dev_priv: The device private structure.
* @cid: The hardware context id used for the query.
*
* See the vmw_fifo_emit_dummy_query documentation.
*/
static int vmw_fifo_emit_dummy_legacy_query(struct vmw_private *dev_priv,
uint32_t cid)
{
/*
* A query wait without a preceding query end will
* actually finish all queries for this cid
* without writing to the query result structure.
*/
struct ttm_buffer_object *bo = &dev_priv->dummy_query_bo->base;
struct {
SVGA3dCmdHeader header;
SVGA3dCmdWaitForQuery body;
} *cmd;
cmd = VMW_FIFO_RESERVE(dev_priv, sizeof(*cmd));
if (unlikely(cmd == NULL))
return -ENOMEM;
cmd->header.id = SVGA_3D_CMD_WAIT_FOR_QUERY;
cmd->header.size = sizeof(cmd->body);
cmd->body.cid = cid;
cmd->body.type = SVGA3D_QUERYTYPE_OCCLUSION;
if (bo->mem.mem_type == TTM_PL_VRAM) {
cmd->body.guestResult.gmrId = SVGA_GMR_FRAMEBUFFER;
cmd->body.guestResult.offset = bo->mem.start << PAGE_SHIFT;
} else {
cmd->body.guestResult.gmrId = bo->mem.start;
cmd->body.guestResult.offset = 0;
}
vmw_fifo_commit(dev_priv, sizeof(*cmd));
return 0;
}
/**
* vmw_fifo_emit_dummy_gb_query - emits a dummy query to the fifo using
* guest-backed resource query commands.
*
* @dev_priv: The device private structure.
* @cid: The hardware context id used for the query.
*
* See the vmw_fifo_emit_dummy_query documentation.
*/
static int vmw_fifo_emit_dummy_gb_query(struct vmw_private *dev_priv,
uint32_t cid)
{
/*
* A query wait without a preceding query end will
* actually finish all queries for this cid
* without writing to the query result structure.
*/
struct ttm_buffer_object *bo = &dev_priv->dummy_query_bo->base;
struct {
SVGA3dCmdHeader header;
SVGA3dCmdWaitForGBQuery body;
} *cmd;
cmd = VMW_FIFO_RESERVE(dev_priv, sizeof(*cmd));
if (unlikely(cmd == NULL))
return -ENOMEM;
cmd->header.id = SVGA_3D_CMD_WAIT_FOR_GB_QUERY;
cmd->header.size = sizeof(cmd->body);
cmd->body.cid = cid;
cmd->body.type = SVGA3D_QUERYTYPE_OCCLUSION;
BUG_ON(bo->mem.mem_type != VMW_PL_MOB);
cmd->body.mobid = bo->mem.start;
cmd->body.offset = 0;
vmw_fifo_commit(dev_priv, sizeof(*cmd));
return 0;
}
/**
* vmw_fifo_emit_dummy_gb_query - emits a dummy query to the fifo using
* appropriate resource query commands.
*
* @dev_priv: The device private structure.
* @cid: The hardware context id used for the query.
*
* This function is used to emit a dummy occlusion query with
* no primitives rendered between query begin and query end.
* It's used to provide a query barrier, in order to know that when
* this query is finished, all preceding queries are also finished.
*
* A Query results structure should have been initialized at the start
* of the dev_priv->dummy_query_bo buffer object. And that buffer object
* must also be either reserved or pinned when this function is called.
*
* Returns -ENOMEM on failure to reserve fifo space.
*/
int vmw_fifo_emit_dummy_query(struct vmw_private *dev_priv,
uint32_t cid)
{
if (dev_priv->has_mob)
return vmw_fifo_emit_dummy_gb_query(dev_priv, cid);
return vmw_fifo_emit_dummy_legacy_query(dev_priv, cid);
}