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added DMA cmd related info

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git-svn-id: file:///srv/svn/repos/haiku/trunk/current@10711 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Rudolf Cornelissen 2005-01-13 12:11:36 +00:00
parent 02f2dfb7cf
commit 0bfacfc2a9
1 changed files with 16 additions and 2 deletions
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18
src/add-ons/accelerants/nvidia/engine/nv_acc_dma.c
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@ -586,9 +586,17 @@ status_t nv_acc_init_dma()
LOG(4,("ACC_DMA: command buffer is at adress $%08x\n",
((uint32)(si->engine.dma.cmdbuffer))));
/* init FIFO via DMA command buffer: */
/* set number of cmd words (b18 - ??) and FIFO offset for first cmd word (b0 - 17) */
/* init FIFO via DMA command buffer. */
/* NV_FIFO_DMA_OPCODE: set number of cmd words (b18 - 28); set FIFO offset for
* first cmd word (b2 - 15); set DMA opcode = method (b29 - 31).
* a 'NOP' is the opcode word $00000000. */
/* note:
* possible DMA opcodes:
* b'000' is 'method' (execute cmd);
* b'001' is 'jump';
* b'002' is 'noninc method' (execute buffer wrap-around);
* b'003' is 'call': return is executed by opcode word $00020000 (b17 = 1). */
/* note also:
* this system uses auto-increments for the FIFO offset adresses. Make sure
* to set new adresses if jumps are needed. */
si->engine.dma.cmdbuffer[0x00] = (1 << 18) | 0x00000;
@ -631,6 +639,10 @@ status_t nv_acc_init_dma()
/* the current first free adress in the DMA buffer is at offset 16 */
si->engine.dma.current = 16;
/* the DMA buffer can hold 8k 32-bit words (it's 32kb in size) */
/* note:
* one word is reserved at the end of the DMA buffer to be able to instruct the
* engine to do a buffer wrap-around!
* (DMA opcode 'noninc method': issue word $20000000.) */
/*si->dma.*/max = 8191;
/* note the current free space we have left in the DMA buffer */
/*si->dma.*/free = /*si->dma.*/max - si->engine.dma.current + 1;
@ -651,6 +663,8 @@ static void nv_start_dma(void)
if (si->engine.dma.current != si->engine.dma.put)
{
si->engine.dma.put = si->engine.dma.current;
/* fixme: is this actually needed? (force some flush somewhere) */
ISAWB(0x03d0, 0x00);
/* dummy read the first adress of the framebuffer: flushes MTRR-WC buffers so
* we know for sure the DMA command buffer received all data. */
dummy = *((char *)(si->framebuffer));