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vmwgfx_fifo.c revision 1.1.1.1
      1 /**************************************************************************
      2  *
      3  * Copyright  2009 VMware, Inc., Palo Alto, CA., USA
      4  * All Rights Reserved.
      5  *
      6  * Permission is hereby granted, free of charge, to any person obtaining a
      7  * copy of this software and associated documentation files (the
      8  * "Software"), to deal in the Software without restriction, including
      9  * without limitation the rights to use, copy, modify, merge, publish,
     10  * distribute, sub license, and/or sell copies of the Software, and to
     11  * permit persons to whom the Software is furnished to do so, subject to
     12  * the following conditions:
     13  *
     14  * The above copyright notice and this permission notice (including the
     15  * next paragraph) shall be included in all copies or substantial portions
     16  * of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     20  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
     21  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
     22  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
     23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
     24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  **************************************************************************/
     27 
     28 #include "vmwgfx_drv.h"
     29 #include <drm/drmP.h>
     30 #include <drm/ttm/ttm_placement.h>
     31 
     32 bool vmw_fifo_have_3d(struct vmw_private *dev_priv)
     33 {
     34 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
     35 	uint32_t fifo_min, hwversion;
     36 	const struct vmw_fifo_state *fifo = &dev_priv->fifo;
     37 
     38 	if (!(dev_priv->capabilities & SVGA_CAP_EXTENDED_FIFO))
     39 		return false;
     40 
     41 	fifo_min = ioread32(fifo_mem  + SVGA_FIFO_MIN);
     42 	if (fifo_min <= SVGA_FIFO_3D_HWVERSION * sizeof(unsigned int))
     43 		return false;
     44 
     45 	hwversion = ioread32(fifo_mem +
     46 			     ((fifo->capabilities &
     47 			       SVGA_FIFO_CAP_3D_HWVERSION_REVISED) ?
     48 			      SVGA_FIFO_3D_HWVERSION_REVISED :
     49 			      SVGA_FIFO_3D_HWVERSION));
     50 
     51 	if (hwversion == 0)
     52 		return false;
     53 
     54 	if (hwversion < SVGA3D_HWVERSION_WS8_B1)
     55 		return false;
     56 
     57 	/* Non-Screen Object path does not support surfaces */
     58 	if (!dev_priv->sou_priv)
     59 		return false;
     60 
     61 	return true;
     62 }
     63 
     64 bool vmw_fifo_have_pitchlock(struct vmw_private *dev_priv)
     65 {
     66 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
     67 	uint32_t caps;
     68 
     69 	if (!(dev_priv->capabilities & SVGA_CAP_EXTENDED_FIFO))
     70 		return false;
     71 
     72 	caps = ioread32(fifo_mem + SVGA_FIFO_CAPABILITIES);
     73 	if (caps & SVGA_FIFO_CAP_PITCHLOCK)
     74 		return true;
     75 
     76 	return false;
     77 }
     78 
     79 int vmw_fifo_init(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
     80 {
     81 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
     82 	uint32_t max;
     83 	uint32_t min;
     84 	uint32_t dummy;
     85 
     86 	fifo->static_buffer_size = VMWGFX_FIFO_STATIC_SIZE;
     87 	fifo->static_buffer = vmalloc(fifo->static_buffer_size);
     88 	if (unlikely(fifo->static_buffer == NULL))
     89 		return -ENOMEM;
     90 
     91 	fifo->dynamic_buffer = NULL;
     92 	fifo->reserved_size = 0;
     93 	fifo->using_bounce_buffer = false;
     94 
     95 	mutex_init(&fifo->fifo_mutex);
     96 	init_rwsem(&fifo->rwsem);
     97 
     98 	/*
     99 	 * Allow mapping the first page read-only to user-space.
    100 	 */
    101 
    102 	DRM_INFO("width %d\n", vmw_read(dev_priv, SVGA_REG_WIDTH));
    103 	DRM_INFO("height %d\n", vmw_read(dev_priv, SVGA_REG_HEIGHT));
    104 	DRM_INFO("bpp %d\n", vmw_read(dev_priv, SVGA_REG_BITS_PER_PIXEL));
    105 
    106 	mutex_lock(&dev_priv->hw_mutex);
    107 	dev_priv->enable_state = vmw_read(dev_priv, SVGA_REG_ENABLE);
    108 	dev_priv->config_done_state = vmw_read(dev_priv, SVGA_REG_CONFIG_DONE);
    109 	dev_priv->traces_state = vmw_read(dev_priv, SVGA_REG_TRACES);
    110 	vmw_write(dev_priv, SVGA_REG_ENABLE, 1);
    111 
    112 	min = 4;
    113 	if (dev_priv->capabilities & SVGA_CAP_EXTENDED_FIFO)
    114 		min = vmw_read(dev_priv, SVGA_REG_MEM_REGS);
    115 	min <<= 2;
    116 
    117 	if (min < PAGE_SIZE)
    118 		min = PAGE_SIZE;
    119 
    120 	iowrite32(min, fifo_mem + SVGA_FIFO_MIN);
    121 	iowrite32(dev_priv->mmio_size, fifo_mem + SVGA_FIFO_MAX);
    122 	wmb();
    123 	iowrite32(min,  fifo_mem + SVGA_FIFO_NEXT_CMD);
    124 	iowrite32(min,  fifo_mem + SVGA_FIFO_STOP);
    125 	iowrite32(0, fifo_mem + SVGA_FIFO_BUSY);
    126 	mb();
    127 
    128 	vmw_write(dev_priv, SVGA_REG_CONFIG_DONE, 1);
    129 	mutex_unlock(&dev_priv->hw_mutex);
    130 
    131 	max = ioread32(fifo_mem + SVGA_FIFO_MAX);
    132 	min = ioread32(fifo_mem  + SVGA_FIFO_MIN);
    133 	fifo->capabilities = ioread32(fifo_mem + SVGA_FIFO_CAPABILITIES);
    134 
    135 	DRM_INFO("Fifo max 0x%08x min 0x%08x cap 0x%08x\n",
    136 		 (unsigned int) max,
    137 		 (unsigned int) min,
    138 		 (unsigned int) fifo->capabilities);
    139 
    140 	atomic_set(&dev_priv->marker_seq, dev_priv->last_read_seqno);
    141 	iowrite32(dev_priv->last_read_seqno, fifo_mem + SVGA_FIFO_FENCE);
    142 	vmw_marker_queue_init(&fifo->marker_queue);
    143 	return vmw_fifo_send_fence(dev_priv, &dummy);
    144 }
    145 
    146 void vmw_fifo_ping_host(struct vmw_private *dev_priv, uint32_t reason)
    147 {
    148 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
    149 
    150 	mutex_lock(&dev_priv->hw_mutex);
    151 
    152 	if (unlikely(ioread32(fifo_mem + SVGA_FIFO_BUSY) == 0)) {
    153 		iowrite32(1, fifo_mem + SVGA_FIFO_BUSY);
    154 		vmw_write(dev_priv, SVGA_REG_SYNC, reason);
    155 	}
    156 
    157 	mutex_unlock(&dev_priv->hw_mutex);
    158 }
    159 
    160 void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
    161 {
    162 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
    163 
    164 	mutex_lock(&dev_priv->hw_mutex);
    165 
    166 	while (vmw_read(dev_priv, SVGA_REG_BUSY) != 0)
    167 		vmw_write(dev_priv, SVGA_REG_SYNC, SVGA_SYNC_GENERIC);
    168 
    169 	dev_priv->last_read_seqno = ioread32(fifo_mem + SVGA_FIFO_FENCE);
    170 
    171 	vmw_write(dev_priv, SVGA_REG_CONFIG_DONE,
    172 		  dev_priv->config_done_state);
    173 	vmw_write(dev_priv, SVGA_REG_ENABLE,
    174 		  dev_priv->enable_state);
    175 	vmw_write(dev_priv, SVGA_REG_TRACES,
    176 		  dev_priv->traces_state);
    177 
    178 	mutex_unlock(&dev_priv->hw_mutex);
    179 	vmw_marker_queue_takedown(&fifo->marker_queue);
    180 
    181 	if (likely(fifo->static_buffer != NULL)) {
    182 		vfree(fifo->static_buffer);
    183 		fifo->static_buffer = NULL;
    184 	}
    185 
    186 	if (likely(fifo->dynamic_buffer != NULL)) {
    187 		vfree(fifo->dynamic_buffer);
    188 		fifo->dynamic_buffer = NULL;
    189 	}
    190 }
    191 
    192 static bool vmw_fifo_is_full(struct vmw_private *dev_priv, uint32_t bytes)
    193 {
    194 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
    195 	uint32_t max = ioread32(fifo_mem + SVGA_FIFO_MAX);
    196 	uint32_t next_cmd = ioread32(fifo_mem + SVGA_FIFO_NEXT_CMD);
    197 	uint32_t min = ioread32(fifo_mem + SVGA_FIFO_MIN);
    198 	uint32_t stop = ioread32(fifo_mem + SVGA_FIFO_STOP);
    199 
    200 	return ((max - next_cmd) + (stop - min) <= bytes);
    201 }
    202 
    203 static int vmw_fifo_wait_noirq(struct vmw_private *dev_priv,
    204 			       uint32_t bytes, bool interruptible,
    205 			       unsigned long timeout)
    206 {
    207 	int ret = 0;
    208 	unsigned long end_jiffies = jiffies + timeout;
    209 	DEFINE_WAIT(__wait);
    210 
    211 	DRM_INFO("Fifo wait noirq.\n");
    212 
    213 	for (;;) {
    214 		prepare_to_wait(&dev_priv->fifo_queue, &__wait,
    215 				(interruptible) ?
    216 				TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
    217 		if (!vmw_fifo_is_full(dev_priv, bytes))
    218 			break;
    219 		if (time_after_eq(jiffies, end_jiffies)) {
    220 			ret = -EBUSY;
    221 			DRM_ERROR("SVGA device lockup.\n");
    222 			break;
    223 		}
    224 		schedule_timeout(1);
    225 		if (interruptible && signal_pending(current)) {
    226 			ret = -ERESTARTSYS;
    227 			break;
    228 		}
    229 	}
    230 	finish_wait(&dev_priv->fifo_queue, &__wait);
    231 	wake_up_all(&dev_priv->fifo_queue);
    232 	DRM_INFO("Fifo noirq exit.\n");
    233 	return ret;
    234 }
    235 
    236 static int vmw_fifo_wait(struct vmw_private *dev_priv,
    237 			 uint32_t bytes, bool interruptible,
    238 			 unsigned long timeout)
    239 {
    240 	long ret = 1L;
    241 	unsigned long irq_flags;
    242 
    243 	if (likely(!vmw_fifo_is_full(dev_priv, bytes)))
    244 		return 0;
    245 
    246 	vmw_fifo_ping_host(dev_priv, SVGA_SYNC_FIFOFULL);
    247 	if (!(dev_priv->capabilities & SVGA_CAP_IRQMASK))
    248 		return vmw_fifo_wait_noirq(dev_priv, bytes,
    249 					   interruptible, timeout);
    250 
    251 	mutex_lock(&dev_priv->hw_mutex);
    252 	if (atomic_add_return(1, &dev_priv->fifo_queue_waiters) > 0) {
    253 		spin_lock_irqsave(&dev_priv->irq_lock, irq_flags);
    254 		outl(SVGA_IRQFLAG_FIFO_PROGRESS,
    255 		     dev_priv->io_start + VMWGFX_IRQSTATUS_PORT);
    256 		dev_priv->irq_mask |= SVGA_IRQFLAG_FIFO_PROGRESS;
    257 		vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
    258 		spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
    259 	}
    260 	mutex_unlock(&dev_priv->hw_mutex);
    261 
    262 	if (interruptible)
    263 		ret = wait_event_interruptible_timeout
    264 		    (dev_priv->fifo_queue,
    265 		     !vmw_fifo_is_full(dev_priv, bytes), timeout);
    266 	else
    267 		ret = wait_event_timeout
    268 		    (dev_priv->fifo_queue,
    269 		     !vmw_fifo_is_full(dev_priv, bytes), timeout);
    270 
    271 	if (unlikely(ret == 0))
    272 		ret = -EBUSY;
    273 	else if (likely(ret > 0))
    274 		ret = 0;
    275 
    276 	mutex_lock(&dev_priv->hw_mutex);
    277 	if (atomic_dec_and_test(&dev_priv->fifo_queue_waiters)) {
    278 		spin_lock_irqsave(&dev_priv->irq_lock, irq_flags);
    279 		dev_priv->irq_mask &= ~SVGA_IRQFLAG_FIFO_PROGRESS;
    280 		vmw_write(dev_priv, SVGA_REG_IRQMASK, dev_priv->irq_mask);
    281 		spin_unlock_irqrestore(&dev_priv->irq_lock, irq_flags);
    282 	}
    283 	mutex_unlock(&dev_priv->hw_mutex);
    284 
    285 	return ret;
    286 }
    287 
    288 /**
    289  * Reserve @bytes number of bytes in the fifo.
    290  *
    291  * This function will return NULL (error) on two conditions:
    292  *  If it timeouts waiting for fifo space, or if @bytes is larger than the
    293  *   available fifo space.
    294  *
    295  * Returns:
    296  *   Pointer to the fifo, or null on error (possible hardware hang).
    297  */
    298 void *vmw_fifo_reserve(struct vmw_private *dev_priv, uint32_t bytes)
    299 {
    300 	struct vmw_fifo_state *fifo_state = &dev_priv->fifo;
    301 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
    302 	uint32_t max;
    303 	uint32_t min;
    304 	uint32_t next_cmd;
    305 	uint32_t reserveable = fifo_state->capabilities & SVGA_FIFO_CAP_RESERVE;
    306 	int ret;
    307 
    308 	mutex_lock(&fifo_state->fifo_mutex);
    309 	max = ioread32(fifo_mem + SVGA_FIFO_MAX);
    310 	min = ioread32(fifo_mem + SVGA_FIFO_MIN);
    311 	next_cmd = ioread32(fifo_mem + SVGA_FIFO_NEXT_CMD);
    312 
    313 	if (unlikely(bytes >= (max - min)))
    314 		goto out_err;
    315 
    316 	BUG_ON(fifo_state->reserved_size != 0);
    317 	BUG_ON(fifo_state->dynamic_buffer != NULL);
    318 
    319 	fifo_state->reserved_size = bytes;
    320 
    321 	while (1) {
    322 		uint32_t stop = ioread32(fifo_mem + SVGA_FIFO_STOP);
    323 		bool need_bounce = false;
    324 		bool reserve_in_place = false;
    325 
    326 		if (next_cmd >= stop) {
    327 			if (likely((next_cmd + bytes < max ||
    328 				    (next_cmd + bytes == max && stop > min))))
    329 				reserve_in_place = true;
    330 
    331 			else if (vmw_fifo_is_full(dev_priv, bytes)) {
    332 				ret = vmw_fifo_wait(dev_priv, bytes,
    333 						    false, 3 * HZ);
    334 				if (unlikely(ret != 0))
    335 					goto out_err;
    336 			} else
    337 				need_bounce = true;
    338 
    339 		} else {
    340 
    341 			if (likely((next_cmd + bytes < stop)))
    342 				reserve_in_place = true;
    343 			else {
    344 				ret = vmw_fifo_wait(dev_priv, bytes,
    345 						    false, 3 * HZ);
    346 				if (unlikely(ret != 0))
    347 					goto out_err;
    348 			}
    349 		}
    350 
    351 		if (reserve_in_place) {
    352 			if (reserveable || bytes <= sizeof(uint32_t)) {
    353 				fifo_state->using_bounce_buffer = false;
    354 
    355 				if (reserveable)
    356 					iowrite32(bytes, fifo_mem +
    357 						  SVGA_FIFO_RESERVED);
    358 				return fifo_mem + (next_cmd >> 2);
    359 			} else {
    360 				need_bounce = true;
    361 			}
    362 		}
    363 
    364 		if (need_bounce) {
    365 			fifo_state->using_bounce_buffer = true;
    366 			if (bytes < fifo_state->static_buffer_size)
    367 				return fifo_state->static_buffer;
    368 			else {
    369 				fifo_state->dynamic_buffer = vmalloc(bytes);
    370 				return fifo_state->dynamic_buffer;
    371 			}
    372 		}
    373 	}
    374 out_err:
    375 	fifo_state->reserved_size = 0;
    376 	mutex_unlock(&fifo_state->fifo_mutex);
    377 	return NULL;
    378 }
    379 
    380 static void vmw_fifo_res_copy(struct vmw_fifo_state *fifo_state,
    381 			      __le32 __iomem *fifo_mem,
    382 			      uint32_t next_cmd,
    383 			      uint32_t max, uint32_t min, uint32_t bytes)
    384 {
    385 	uint32_t chunk_size = max - next_cmd;
    386 	uint32_t rest;
    387 	uint32_t *buffer = (fifo_state->dynamic_buffer != NULL) ?
    388 	    fifo_state->dynamic_buffer : fifo_state->static_buffer;
    389 
    390 	if (bytes < chunk_size)
    391 		chunk_size = bytes;
    392 
    393 	iowrite32(bytes, fifo_mem + SVGA_FIFO_RESERVED);
    394 	mb();
    395 	memcpy_toio(fifo_mem + (next_cmd >> 2), buffer, chunk_size);
    396 	rest = bytes - chunk_size;
    397 	if (rest)
    398 		memcpy_toio(fifo_mem + (min >> 2), buffer + (chunk_size >> 2),
    399 			    rest);
    400 }
    401 
    402 static void vmw_fifo_slow_copy(struct vmw_fifo_state *fifo_state,
    403 			       __le32 __iomem *fifo_mem,
    404 			       uint32_t next_cmd,
    405 			       uint32_t max, uint32_t min, uint32_t bytes)
    406 {
    407 	uint32_t *buffer = (fifo_state->dynamic_buffer != NULL) ?
    408 	    fifo_state->dynamic_buffer : fifo_state->static_buffer;
    409 
    410 	while (bytes > 0) {
    411 		iowrite32(*buffer++, fifo_mem + (next_cmd >> 2));
    412 		next_cmd += sizeof(uint32_t);
    413 		if (unlikely(next_cmd == max))
    414 			next_cmd = min;
    415 		mb();
    416 		iowrite32(next_cmd, fifo_mem + SVGA_FIFO_NEXT_CMD);
    417 		mb();
    418 		bytes -= sizeof(uint32_t);
    419 	}
    420 }
    421 
    422 void vmw_fifo_commit(struct vmw_private *dev_priv, uint32_t bytes)
    423 {
    424 	struct vmw_fifo_state *fifo_state = &dev_priv->fifo;
    425 	__le32 __iomem *fifo_mem = dev_priv->mmio_virt;
    426 	uint32_t next_cmd = ioread32(fifo_mem + SVGA_FIFO_NEXT_CMD);
    427 	uint32_t max = ioread32(fifo_mem + SVGA_FIFO_MAX);
    428 	uint32_t min = ioread32(fifo_mem + SVGA_FIFO_MIN);
    429 	bool reserveable = fifo_state->capabilities & SVGA_FIFO_CAP_RESERVE;
    430 
    431 	BUG_ON((bytes & 3) != 0);
    432 	BUG_ON(bytes > fifo_state->reserved_size);
    433 
    434 	fifo_state->reserved_size = 0;
    435 
    436 	if (fifo_state->using_bounce_buffer) {
    437 		if (reserveable)
    438 			vmw_fifo_res_copy(fifo_state, fifo_mem,
    439 					  next_cmd, max, min, bytes);
    440 		else
    441 			vmw_fifo_slow_copy(fifo_state, fifo_mem,
    442 					   next_cmd, max, min, bytes);
    443 
    444 		if (fifo_state->dynamic_buffer) {
    445 			vfree(fifo_state->dynamic_buffer);
    446 			fifo_state->dynamic_buffer = NULL;
    447 		}
    448 
    449 	}
    450 
    451 	down_write(&fifo_state->rwsem);
    452 	if (fifo_state->using_bounce_buffer || reserveable) {
    453 		next_cmd += bytes;
    454 		if (next_cmd >= max)
    455 			next_cmd -= max - min;
    456 		mb();
    457 		iowrite32(next_cmd, fifo_mem + SVGA_FIFO_NEXT_CMD);
    458 	}
    459 
    460 	if (reserveable)
    461 		iowrite32(0, fifo_mem + SVGA_FIFO_RESERVED);
    462 	mb();
    463 	up_write(&fifo_state->rwsem);
    464 	vmw_fifo_ping_host(dev_priv, SVGA_SYNC_GENERIC);
    465 	mutex_unlock(&fifo_state->fifo_mutex);
    466 }
    467 
    468 int vmw_fifo_send_fence(struct vmw_private *dev_priv, uint32_t *seqno)
    469 {
    470 	struct vmw_fifo_state *fifo_state = &dev_priv->fifo;
    471 	struct svga_fifo_cmd_fence *cmd_fence;
    472 	void *fm;
    473 	int ret = 0;
    474 	uint32_t bytes = sizeof(__le32) + sizeof(*cmd_fence);
    475 
    476 	fm = vmw_fifo_reserve(dev_priv, bytes);
    477 	if (unlikely(fm == NULL)) {
    478 		*seqno = atomic_read(&dev_priv->marker_seq);
    479 		ret = -ENOMEM;
    480 		(void)vmw_fallback_wait(dev_priv, false, true, *seqno,
    481 					false, 3*HZ);
    482 		goto out_err;
    483 	}
    484 
    485 	do {
    486 		*seqno = atomic_add_return(1, &dev_priv->marker_seq);
    487 	} while (*seqno == 0);
    488 
    489 	if (!(fifo_state->capabilities & SVGA_FIFO_CAP_FENCE)) {
    490 
    491 		/*
    492 		 * Don't request hardware to send a fence. The
    493 		 * waiting code in vmwgfx_irq.c will emulate this.
    494 		 */
    495 
    496 		vmw_fifo_commit(dev_priv, 0);
    497 		return 0;
    498 	}
    499 
    500 	*(__le32 *) fm = cpu_to_le32(SVGA_CMD_FENCE);
    501 	cmd_fence = (struct svga_fifo_cmd_fence *)
    502 	    ((unsigned long)fm + sizeof(__le32));
    503 
    504 	iowrite32(*seqno, &cmd_fence->fence);
    505 	vmw_fifo_commit(dev_priv, bytes);
    506 	(void) vmw_marker_push(&fifo_state->marker_queue, *seqno);
    507 	vmw_update_seqno(dev_priv, fifo_state);
    508 
    509 out_err:
    510 	return ret;
    511 }
    512 
    513 /**
    514  * vmw_fifo_emit_dummy_query - emits a dummy query to the fifo.
    515  *
    516  * @dev_priv: The device private structure.
    517  * @cid: The hardware context id used for the query.
    518  *
    519  * This function is used to emit a dummy occlusion query with
    520  * no primitives rendered between query begin and query end.
    521  * It's used to provide a query barrier, in order to know that when
    522  * this query is finished, all preceding queries are also finished.
    523  *
    524  * A Query results structure should have been initialized at the start
    525  * of the dev_priv->dummy_query_bo buffer object. And that buffer object
    526  * must also be either reserved or pinned when this function is called.
    527  *
    528  * Returns -ENOMEM on failure to reserve fifo space.
    529  */
    530 int vmw_fifo_emit_dummy_query(struct vmw_private *dev_priv,
    531 			      uint32_t cid)
    532 {
    533 	/*
    534 	 * A query wait without a preceding query end will
    535 	 * actually finish all queries for this cid
    536 	 * without writing to the query result structure.
    537 	 */
    538 
    539 	struct ttm_buffer_object *bo = dev_priv->dummy_query_bo;
    540 	struct {
    541 		SVGA3dCmdHeader header;
    542 		SVGA3dCmdWaitForQuery body;
    543 	} *cmd;
    544 
    545 	cmd = vmw_fifo_reserve(dev_priv, sizeof(*cmd));
    546 
    547 	if (unlikely(cmd == NULL)) {
    548 		DRM_ERROR("Out of fifo space for dummy query.\n");
    549 		return -ENOMEM;
    550 	}
    551 
    552 	cmd->header.id = SVGA_3D_CMD_WAIT_FOR_QUERY;
    553 	cmd->header.size = sizeof(cmd->body);
    554 	cmd->body.cid = cid;
    555 	cmd->body.type = SVGA3D_QUERYTYPE_OCCLUSION;
    556 
    557 	if (bo->mem.mem_type == TTM_PL_VRAM) {
    558 		cmd->body.guestResult.gmrId = SVGA_GMR_FRAMEBUFFER;
    559 		cmd->body.guestResult.offset = bo->offset;
    560 	} else {
    561 		cmd->body.guestResult.gmrId = bo->mem.start;
    562 		cmd->body.guestResult.offset = 0;
    563 	}
    564 
    565 	vmw_fifo_commit(dev_priv, sizeof(*cmd));
    566 
    567 	return 0;
    568 }
    569