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/*
* Copyright (C) 2007 Ben Skeggs.
* 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 THE COPYRIGHT OWNER(S) 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 "nouveau_drv.h"
#include "nouveau_dma.h"
#include "nouveau_vmm.h"
#include <nvif/user.h>
/* Fetch and adjust GPU GET pointer
*
* Returns:
* value >= 0, the adjusted GET pointer
* -EINVAL if GET pointer currently outside main push buffer
* -EBUSY if timeout exceeded
*/
static inline int
READ_GET(struct nouveau_channel *chan, uint64_t *prev_get, int *timeout)
{
uint64_t val;
val = nvif_rd32(chan->userd, chan->user_get);
/* reset counter as long as GET is still advancing, this is
* to avoid misdetecting a GPU lockup if the GPU happens to
* just be processing an operation that takes a long time
*/
if (val != *prev_get) {
*prev_get = val;
*timeout = 0;
}
if ((++*timeout & 0xff) == 0) {
udelay(1);
if (*timeout > 100000)
return -EBUSY;
}
if (val < chan->push.addr ||
val > chan->push.addr + (chan->dma.max << 2))
return -EINVAL;
return (val - chan->push.addr) >> 2;
}
int
nouveau_dma_wait(struct nouveau_channel *chan, int size)
{
uint64_t prev_get = 0;
int cnt = 0, get;
while (chan->dma.free < size) {
get = READ_GET(chan, &prev_get, &cnt);
if (unlikely(get == -EBUSY))
return -EBUSY;
/* loop until we have a usable GET pointer. the value
* we read from the GPU may be outside the main ring if
* PFIFO is processing a buffer called from the main ring,
* discard these values until something sensible is seen.
*
* the other case we discard GET is while the GPU is fetching
* from the SKIPS area, so the code below doesn't have to deal
* with some fun corner cases.
*/
if (unlikely(get == -EINVAL) || get < NOUVEAU_DMA_SKIPS)
continue;
if (get <= chan->dma.cur) {
/* engine is fetching behind us, or is completely
* idle (GET == PUT) so we have free space up until
* the end of the push buffer
*
* we can only hit that path once per call due to
* looping back to the beginning of the push buffer,
* we'll hit the fetching-ahead-of-us path from that
* point on.
*
* the *one* exception to that rule is if we read
* GET==PUT, in which case the below conditional will
* always succeed and break us out of the wait loop.
*/
chan->dma.free = chan->dma.max - chan->dma.cur;
if (chan->dma.free >= size)
break;
/* not enough space left at the end of the push buffer,
* instruct the GPU to jump back to the start right
* after processing the currently pending commands.
*/
OUT_RING(chan, chan->push.addr | 0x20000000);
/* wait for GET to depart from the skips area.
* prevents writing GET==PUT and causing a race
* condition that causes us to think the GPU is
* idle when it's not.
*/
do {
get = READ_GET(chan, &prev_get, &cnt);
if (unlikely(get == -EBUSY))
return -EBUSY;
if (unlikely(get == -EINVAL))
continue;
} while (get <= NOUVEAU_DMA_SKIPS);
WRITE_PUT(NOUVEAU_DMA_SKIPS);
/* we're now submitting commands at the start of
* the push buffer.
*/
chan->dma.cur =
chan->dma.put = NOUVEAU_DMA_SKIPS;
}
/* engine fetching ahead of us, we have space up until the
* current GET pointer. the "- 1" is to ensure there's
* space left to emit a jump back to the beginning of the
* push buffer if we require it. we can never get GET == PUT
* here, so this is safe.
*/
chan->dma.free = get - chan->dma.cur - 1;
}
return 0;
}
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