path: root/usr/src/uts/intel/io/radeon/r300_cmdbuf.c

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */
/*
 * r300_cmdbuf.c -- Command buffer emission for R300 -*- linux-c -*-
 *
 * Copyright (C) The Weather Channel, Inc.  2002.
 * Copyright (C) 2004 Nicolai Haehnle.
 * All Rights Reserved.
 *
 * The Weather Channel (TM) funded Tungsten Graphics to develop the
 * initial release of the Radeon 8500 driver under the XFree86 license.
 * This notice must be preserved.
 *
 * 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.
 *
 * Authors:
 *    Nicolai Haehnle <prefect_@gmx.net>
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include "drm.h"
#include "radeon_drm.h"
#include "drmP.h"
#include "radeon_drv.h"
#include "r300_reg.h"

#define	R300_SIMULTANEOUS_CLIPRECTS		4

/*
 * Values for R300_RE_CLIPRECT_CNTL depending on the number of
 * cliprects
 */
static const int r300_cliprect_cntl[4] = {
	0xAAAA,
	0xEEEE,
	0xFEFE,
	0xFFFE
};

/*
 * Emit up to R300_SIMULTANEOUS_CLIPRECTS cliprects from the given command
 * buffer, starting with index n.
 */
static int r300_emit_cliprects(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf, int n)
{
	drm_clip_rect_t box;
	int nr;
	int i;
	RING_LOCALS;

	nr = cmdbuf->nbox - n;
	if (nr > R300_SIMULTANEOUS_CLIPRECTS)
		nr = R300_SIMULTANEOUS_CLIPRECTS;

	DRM_DEBUG("%i cliprects\n", nr);

	if (nr) {
		BEGIN_RING(6 + nr * 2);
		OUT_RING(CP_PACKET0(R300_RE_CLIPRECT_TL_0, nr * 2 - 1));

		for (i = 0; i < nr; ++i) {
			if (DRM_COPY_FROM_USER_UNCHECKED
			    (&box, &cmdbuf->boxes[n + i], sizeof (box))) {
				DRM_ERROR("copy cliprect faulted\n");
				return (EFAULT);
			}

			box.x1 =
			    (box.x1 +
			    R300_CLIPRECT_OFFSET) & R300_CLIPRECT_MASK;
			box.y1 =
			    (box.y1 +
			    R300_CLIPRECT_OFFSET) & R300_CLIPRECT_MASK;
			box.x2 =
			    (box.x2 +
			    R300_CLIPRECT_OFFSET) & R300_CLIPRECT_MASK;
			box.y2 =
			    (box.y2 +
			    R300_CLIPRECT_OFFSET) & R300_CLIPRECT_MASK;

			OUT_RING((box.x1 << R300_CLIPRECT_X_SHIFT) |
			    (box.y1 << R300_CLIPRECT_Y_SHIFT));
			OUT_RING((box.x2 << R300_CLIPRECT_X_SHIFT) |
			    (box.y2 << R300_CLIPRECT_Y_SHIFT));
		}

		OUT_RING_REG(R300_RE_CLIPRECT_CNTL, r300_cliprect_cntl[nr - 1]);

		/*
		 * TODO/SECURITY: Force scissors to a safe value, otherwise
		 * the client might be able to trample over memory.
		 * The impact should be very limited, but I'd rather be safe
		 * than sorry.
		 */
		OUT_RING(CP_PACKET0(R300_RE_SCISSORS_TL, 1));
		OUT_RING(0);
		OUT_RING(R300_SCISSORS_X_MASK | R300_SCISSORS_Y_MASK);
		ADVANCE_RING();
	} else {
		/*
		 * Why we allow zero cliprect rendering:
		 * There are some commands in a command buffer that must be
		 * submitted even when there are no cliprects, e.g. DMA buffer
		 * discard or state setting (though state setting could be
		 * avoided by simulating a loss of context).
		 *
		 * Now since the cmdbuf interface is so chaotic right now (and
		 * is bound to remain that way for a bit until things settle
		 * down), it is basically impossible to filter out the commands
		 * that are necessary and those that aren't.
		 *
		 * So I choose the safe way and don't do any filtering at all;
		 * instead, I simply set up the engine so that all rendering
		 * can't produce any fragments.
		 */
		BEGIN_RING(2);
		OUT_RING_REG(R300_RE_CLIPRECT_CNTL, 0);
		ADVANCE_RING();
	}

	return (0);
}

static u8 r300_reg_flags[0x10000 >> 2];

void
r300_init_reg_flags(void)
{
	int i;
	(void) memset(r300_reg_flags, 0, 0x10000 >> 2);
#define	ADD_RANGE_MARK(reg, count, mark) \
		for (i = ((reg) >> 2); i < ((reg) >> 2) + (count); i++)\
			r300_reg_flags[i] |= (mark);

#define	MARK_SAFE		1
#define	MARK_CHECK_OFFSET	2

#define	ADD_RANGE(reg, count)	ADD_RANGE_MARK(reg, count, MARK_SAFE)

	/* these match cmducs() command in r300_driver/r300/r300_cmdbuf.c */
	ADD_RANGE(R300_SE_VPORT_XSCALE, 6);
	ADD_RANGE(0x2080, 1);
	ADD_RANGE(R300_SE_VTE_CNTL, 2);
	ADD_RANGE(0x2134, 2);
	ADD_RANGE(0x2140, 1);
	ADD_RANGE(R300_VAP_INPUT_CNTL_0, 2);
	ADD_RANGE(0x21DC, 1);
	ADD_RANGE(0x221C, 1);
	ADD_RANGE(0x2220, 4);
	ADD_RANGE(0x2288, 1);
	ADD_RANGE(R300_VAP_OUTPUT_VTX_FMT_0, 2);
	ADD_RANGE(R300_VAP_PVS_CNTL_1, 3);
	ADD_RANGE(R300_GB_ENABLE, 1);
	ADD_RANGE(R300_GB_MSPOS0, 5);
	ADD_RANGE(R300_TX_CNTL, 1);
	ADD_RANGE(R300_TX_ENABLE, 1);
	ADD_RANGE(0x4200, 4);
	ADD_RANGE(0x4214, 1);
	ADD_RANGE(R300_RE_POINTSIZE, 1);
	ADD_RANGE(0x4230, 3);
	ADD_RANGE(R300_RE_LINE_CNT, 1);
	ADD_RANGE(0x4238, 1);
	ADD_RANGE(0x4260, 3);
	ADD_RANGE(0x4274, 4);
	ADD_RANGE(0x4288, 5);
	ADD_RANGE(0x42A0, 1);
	ADD_RANGE(R300_RE_ZBIAS_T_FACTOR, 4);
	ADD_RANGE(0x42B4, 1);
	ADD_RANGE(R300_RE_CULL_CNTL, 1);
	ADD_RANGE(0x42C0, 2);
	ADD_RANGE(R300_RS_CNTL_0, 2);
	ADD_RANGE(R300_RS_INTERP_0, 8);
	ADD_RANGE(R300_RS_ROUTE_0, 8);
	ADD_RANGE(0x43A4, 2);
	ADD_RANGE(0x43E8, 1);
	ADD_RANGE(R300_PFS_CNTL_0, 3);
	ADD_RANGE(R300_PFS_NODE_0, 4);
	ADD_RANGE(R300_PFS_TEXI_0, 64);
	ADD_RANGE(0x46A4, 5);
	ADD_RANGE(R300_PFS_INSTR0_0, 64);
	ADD_RANGE(R300_PFS_INSTR1_0, 64);
	ADD_RANGE(R300_PFS_INSTR2_0, 64);
	ADD_RANGE(R300_PFS_INSTR3_0, 64);
	ADD_RANGE(0x4BC0, 1);
	ADD_RANGE(0x4BC8, 3);
	ADD_RANGE(R300_PP_ALPHA_TEST, 2);
	ADD_RANGE(0x4BD8, 1);
	ADD_RANGE(R300_PFS_PARAM_0_X, 64);
	ADD_RANGE(0x4E00, 1);
	ADD_RANGE(R300_RB3D_CBLEND, 2);
	ADD_RANGE(R300_RB3D_COLORMASK, 1);
	ADD_RANGE(0x4E10, 3);
	ADD_RANGE_MARK(R300_RB3D_COLOROFFSET0, 1, MARK_CHECK_OFFSET);
					/* check offset */
	ADD_RANGE(R300_RB3D_COLORPITCH0, 1);
	ADD_RANGE(0x4E50, 9);
	ADD_RANGE(0x4E88, 1);
	ADD_RANGE(0x4EA0, 2);
	ADD_RANGE(R300_RB3D_ZSTENCIL_CNTL_0, 3);
	ADD_RANGE(0x4F10, 4);
	ADD_RANGE_MARK(R300_RB3D_DEPTHOFFSET, 1, MARK_CHECK_OFFSET);
					/* check offset */
	ADD_RANGE(R300_RB3D_DEPTHPITCH, 1);
	ADD_RANGE(0x4F28, 1);
	ADD_RANGE(0x4F30, 2);
	ADD_RANGE(0x4F44, 1);
	ADD_RANGE(0x4F54, 1);

	ADD_RANGE(R300_TX_FILTER_0, 16);
	ADD_RANGE(R300_TX_FILTER1_0, 16);
	ADD_RANGE(R300_TX_SIZE_0, 16);
	ADD_RANGE(R300_TX_FORMAT_0, 16);
	ADD_RANGE(R300_TX_PITCH_0, 16);
	/* Texture offset is dangerous and needs more checking */
	ADD_RANGE_MARK(R300_TX_OFFSET_0, 16, MARK_CHECK_OFFSET);
	ADD_RANGE(R300_TX_CHROMA_KEY_0, 16);
	ADD_RANGE(R300_TX_BORDER_COLOR_0, 16);

	/* Sporadic registers used as primitives are emitted */
	ADD_RANGE(0x4f18, 1);
	ADD_RANGE(R300_RB3D_DSTCACHE_CTLSTAT, 1);
	ADD_RANGE(R300_VAP_INPUT_ROUTE_0_0, 8);
	ADD_RANGE(R300_VAP_INPUT_ROUTE_1_0, 8);

}

static __inline__ int r300_check_range(unsigned reg, int count)
{
	int i;
	if (reg & ~0xffff)
		return (-1);
	for (i = (reg >> 2); i < (reg >> 2) + count; i++)
		if (r300_reg_flags[i] != MARK_SAFE)
			return (1);
	return (0);
}

static inline int
r300_emit_carefully_checked_packet0(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf, drm_r300_cmd_header_t header)
{
	int reg;
	int sz;
	int i;
	int values[64];
	RING_LOCALS;

	sz = header.packet0.count;
	reg = (header.packet0.reghi << 8) | header.packet0.reglo;

	if ((sz > 64) || (sz < 0)) {
		DRM_ERROR("Cannot emit more than 64 values at a time "
		    "(reg=%04x sz=%d)\n", reg, sz);
		return (EINVAL);
	}
	for (i = 0; i < sz; i++) {
		values[i] = ((int *)(uintptr_t)cmdbuf->buf)[i];
		switch (r300_reg_flags[(reg >> 2) + i]) {
		case MARK_SAFE:
			break;
		case MARK_CHECK_OFFSET:
			if (!RADEON_CHECK_OFFSET(dev_priv, (u32) values[i])) {
				DRM_ERROR("Offset failed range check "
				    "(reg=%04x sz=%d)\n", reg, sz);
				return (EINVAL);
			}
			break;
		default:
			DRM_ERROR("Register %04x failed check as flag=%02x\n",
			    reg + i * 4, r300_reg_flags[(reg >> 2) + i]);
			return (EINVAL);
		}
	}

	BEGIN_RING(1 + sz);
	OUT_RING(CP_PACKET0(reg, sz - 1));
	OUT_RING_TABLE(values, sz);
	ADVANCE_RING();

	cmdbuf->buf += sz * 4;
	cmdbuf->bufsz -= sz * 4;

	return (0);
}

/*
 * Emits a packet0 setting arbitrary registers.
 * Called by r300_do_cp_cmdbuf.
 *
 * Note that checks are performed on contents and addresses of the registers
 */
static __inline__ int r300_emit_packet0(drm_radeon_private_t *dev_priv,
					drm_radeon_kcmd_buffer_t *cmdbuf,
					drm_r300_cmd_header_t header)
{
	int reg;
	int sz;
	RING_LOCALS;

	sz = header.packet0.count;
	reg = (header.packet0.reghi << 8) | header.packet0.reglo;

	if (!sz)
		return (0);

	if (sz * 4 > cmdbuf->bufsz)
		return (EINVAL);

	if (reg + sz * 4 >= 0x10000) {
		DRM_ERROR("No such registers in hardware reg=%04x sz=%d\n",
		    reg, sz);
		return (EINVAL);
	}

	if (r300_check_range(reg, sz)) {
		/* go and check everything */
		return (r300_emit_carefully_checked_packet0(dev_priv,
		    cmdbuf, header));
	}
	/*
	 * the rest of the data is safe to emit, whatever the values
	 * the user passed
	 */

	BEGIN_RING(1 + sz);
	OUT_RING(CP_PACKET0(reg, sz - 1));
	OUT_RING_TABLE(cmdbuf->buf, sz);
	ADVANCE_RING();

	cmdbuf->buf += sz * 4;
	cmdbuf->bufsz -= sz * 4;

	return (0);
}

/*
 * Uploads user-supplied vertex program instructions or parameters onto
 * the graphics card.
 * Called by r300_do_cp_cmdbuf.
 */
static inline int r300_emit_vpu(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf, drm_r300_cmd_header_t header)
{
	int sz;
	int addr;
	RING_LOCALS;

	sz = header.vpu.count;
	addr = (header.vpu.adrhi << 8) | header.vpu.adrlo;

	if (!sz)
		return (0);
	if (sz * 16 > cmdbuf->bufsz)
		return (EINVAL);

	BEGIN_RING(5 + sz * 4);
	/* Wait for VAP to come to senses.. */
	/*
	 * there is no need to emit it multiple times, (only once before
	 * VAP is programmed, but this optimization is for later
	 */
	OUT_RING_REG(R300_VAP_PVS_WAITIDLE, 0);
	OUT_RING_REG(R300_VAP_PVS_UPLOAD_ADDRESS, addr);
	OUT_RING(CP_PACKET0_TABLE(R300_VAP_PVS_UPLOAD_DATA, sz * 4 - 1));
	OUT_RING_TABLE(cmdbuf->buf, sz * 4);

	ADVANCE_RING();

	cmdbuf->buf += sz * 16;
	cmdbuf->bufsz -= sz * 16;

	return (0);
}

/*
 * Emit a clear packet from userspace.
 * Called by r300_emit_packet3.
 */
static inline int r300_emit_clear(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf)
{
	RING_LOCALS;

	if (8 * 4 > cmdbuf->bufsz)
		return (EINVAL);

	BEGIN_RING(10);
	OUT_RING(CP_PACKET3(R200_3D_DRAW_IMMD_2, 8));
	OUT_RING(R300_PRIM_TYPE_POINT | R300_PRIM_WALK_RING |
	    (1 << R300_PRIM_NUM_VERTICES_SHIFT));
	OUT_RING_TABLE(cmdbuf->buf, 8);
	ADVANCE_RING();

	cmdbuf->buf += 8 * 4;
	cmdbuf->bufsz -= 8 * 4;

	return (0);
}

static inline int r300_emit_3d_load_vbpntr(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf, u32 header)
{
	int count, i, k;
#define	MAX_ARRAY_PACKET		64
	u32 payload[MAX_ARRAY_PACKET];
	u32 narrays;
	RING_LOCALS;

	count = (header >> 16) & 0x3fff;

	if ((count + 1) > MAX_ARRAY_PACKET) {
		DRM_ERROR("Too large payload in 3D_LOAD_VBPNTR (count=%d)\n",
		    count);
		return (EINVAL);
	}
	(void) memset(payload, 0, MAX_ARRAY_PACKET * 4);
	(void) memcpy(payload, cmdbuf->buf + 4, (count + 1) * 4);

	/* carefully check packet contents */

	narrays = payload[0];
	k = 0;
	i = 1;
	while ((k < narrays) && (i < (count + 1))) {
		i++;		/* skip attribute field */
		if (!RADEON_CHECK_OFFSET(dev_priv, payload[i])) {
			DRM_ERROR("Offset failed range check (k=%d i=%d) "
			    "while processing 3D_LOAD_VBPNTR packet.\n",
			    k, i);
			return (EINVAL);
		}
		k++;
		i++;
		if (k == narrays)
			break;
		/* have one more to process, they come in pairs */
		if (!RADEON_CHECK_OFFSET(dev_priv, payload[i])) {
			DRM_ERROR("Offset failed range check (k=%d i=%d) "
			    "while processing 3D_LOAD_VBPNTR packet.\n",
			    k, i);
			return (EINVAL);
		}
		k++;
		i++;
	}
	/* do the counts match what we expect ? */
	if ((k != narrays) || (i != (count + 1))) {
		DRM_ERROR("Malformed 3D_LOAD_VBPNTR packet "
		    "(k=%d i=%d narrays=%d count+1=%d).\n",
		    k, i, narrays, count + 1);
		return (EINVAL);
	}

	/* all clear, output packet */

	BEGIN_RING(count + 2);
	OUT_RING(header);
	OUT_RING_TABLE(payload, count + 1);
	ADVANCE_RING();

	cmdbuf->buf += (count + 2) * 4;
	cmdbuf->bufsz -= (count + 2) * 4;

	return (0);
}

static inline int r300_emit_bitblt_multi(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf)
{
	u32 *cmd = (u32 *)(uintptr_t)cmdbuf->buf;
	int count, ret;
	RING_LOCALS;

	count = (cmd[0] >> 16) & 0x3fff;

	if (cmd[0] & 0x8000) {
		u32 offset;

		if (cmd[1] & (RADEON_GMC_SRC_PITCH_OFFSET_CNTL |
		    RADEON_GMC_DST_PITCH_OFFSET_CNTL)) {
			offset = cmd[2] << 10;
			ret = !RADEON_CHECK_OFFSET(dev_priv, offset);
			if (ret) {
				DRM_ERROR("Invalid bitblt first offset "
				    "is %08X\n", offset);
				return (EINVAL);
			}
		}

		if ((cmd[1] & RADEON_GMC_SRC_PITCH_OFFSET_CNTL) &&
		    (cmd[1] & RADEON_GMC_DST_PITCH_OFFSET_CNTL)) {
			offset = cmd[3] << 10;
			ret = !RADEON_CHECK_OFFSET(dev_priv, offset);
			if (ret) {
				DRM_ERROR("Invalid bitblt second offset "
				    "is %08X\n", offset);
				return (EINVAL);
			}

		}
	}

	BEGIN_RING(count+2);
	OUT_RING(cmd[0]);
	OUT_RING_TABLE((cmdbuf->buf + 4), count + 1);
	ADVANCE_RING();

	cmdbuf->buf += (count+2)*4;
	cmdbuf->bufsz -= (count+2)*4;

	return (0);
}


static inline int r300_emit_indx_buffer(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf)
{
	u32 *cmd = (u32 *)(uintptr_t)cmdbuf->buf;
	int count, ret;
	RING_LOCALS;

	count = (cmd[0]>>16) & 0x3fff;

	if ((cmd[1] & 0x8000ffff) != 0x80000810) {
		DRM_ERROR("Invalid indx_buffer reg address %08X\n", cmd[1]);
		return (EINVAL);
	}
	ret = !RADEON_CHECK_OFFSET(dev_priv, cmd[2]);
	if (ret) {
		DRM_ERROR("Invalid indx_buffer offset is %08X\n", cmd[2]);
		return (EINVAL);
	}

	BEGIN_RING(count+2);
	OUT_RING(cmd[0]);
	OUT_RING_TABLE(cmdbuf->buf + 4, count + 1);
	ADVANCE_RING();

	cmdbuf->buf += (count+2)*4;
	cmdbuf->bufsz -= (count+2)*4;

	return (0);
}


static __inline__ int r300_emit_raw_packet3(drm_radeon_private_t *dev_priv,
					    drm_radeon_kcmd_buffer_t *cmdbuf)
{
	u32 header;
	int count;
	RING_LOCALS;

	if (4 > cmdbuf->bufsz)
		return (EINVAL);

	/*
	 * Fixme !! This simply emits a packet without much checking.
	 * We need to be smarter.
	 */

	/* obtain first word - actual packet3 header */
	header = *(u32 *)(uintptr_t)cmdbuf->buf;

	/* Is it packet 3 ? */
	if ((header >> 30) != 0x3) {
		DRM_ERROR("Not a packet3 header (0x%08x)\n", header);
		return (EINVAL);
	}

	count = (header >> 16) & 0x3fff;

	/* Check again now that we know how much data to expect */
	if ((count + 2) * 4 > cmdbuf->bufsz) {
		DRM_ERROR("Expected packet3 of length %d but have only "
		    "%d bytes left\n", (count + 2) * 4, cmdbuf->bufsz);
		return (EINVAL);
	}

	/* Is it a packet type we know about ? */
	switch (header & 0xff00) {
	case RADEON_3D_LOAD_VBPNTR:	/* load vertex array pointers */
		return (r300_emit_3d_load_vbpntr(dev_priv, cmdbuf, header));

	case RADEON_CNTL_BITBLT_MULTI:
		return (r300_emit_bitblt_multi(dev_priv, cmdbuf));

	case RADEON_CP_INDX_BUFFER:
			// DRAW_INDX_2 without INDX_BUFFER seems to lock
			// up the GPU
		return (r300_emit_indx_buffer(dev_priv, cmdbuf));

	case RADEON_CP_3D_DRAW_IMMD_2:
			/* triggers drawing using in-packet vertex data */
	case RADEON_CP_3D_DRAW_VBUF_2:
			/* triggers drawing of vertex buffers setup elsewhere */
	case RADEON_CP_3D_DRAW_INDX_2:
			/* triggers drawing using indices to vertex buffer */
	case RADEON_WAIT_FOR_IDLE:
	case RADEON_CP_NOP:
		/* these packets are safe */
		break;
	default:
		DRM_ERROR("Unknown packet3 header (0x%08x)\n", header);
		return (EINVAL);
	}

	BEGIN_RING(count + 2);
	OUT_RING(header);
	OUT_RING_TABLE((cmdbuf->buf + 4), count + 1);
	ADVANCE_RING();

	cmdbuf->buf += (count + 2) * 4;
	cmdbuf->bufsz -= (count + 2) * 4;

	return (0);
}

/*
 * Emit a rendering packet3 from userspace.
 * Called by r300_do_cp_cmdbuf.
 */
static __inline__ int r300_emit_packet3(drm_radeon_private_t *dev_priv,
    drm_radeon_kcmd_buffer_t *cmdbuf, drm_r300_cmd_header_t header)
{
	int n;
	int ret;
	char *orig_buf = cmdbuf->buf;
	int orig_bufsz = cmdbuf->bufsz;

	/*
	 * This is a do-while-loop so that we run the interior at least once,
	 * even if cmdbuf->nbox is 0. Compare r300_emit_cliprects for rationale.
	 */
	n = 0;
	do {
		if (cmdbuf->nbox > R300_SIMULTANEOUS_CLIPRECTS) {
			ret = r300_emit_cliprects(dev_priv, cmdbuf, n);
			if (ret)
				return (ret);

			cmdbuf->buf = orig_buf;
			cmdbuf->bufsz = orig_bufsz;
		}

		switch (header.packet3.packet) {
		case R300_CMD_PACKET3_CLEAR:
			DRM_DEBUG("R300_CMD_PACKET3_CLEAR\n");
			ret = r300_emit_clear(dev_priv, cmdbuf);
			if (ret) {
				DRM_ERROR("r300_emit_clear failed\n");
				return (ret);
			}
			break;

		case R300_CMD_PACKET3_RAW:
			DRM_DEBUG("R300_CMD_PACKET3_RAW\n");
			ret = r300_emit_raw_packet3(dev_priv, cmdbuf);
			if (ret) {
				DRM_ERROR("r300_emit_raw_packet3 failed\n");
				return (ret);
			}
			break;

		default:
			DRM_ERROR("bad packet3 type %i at %p\n",
			    header.packet3.packet,
			    cmdbuf->buf - sizeof (header));
			return (EINVAL);
		}

		n += R300_SIMULTANEOUS_CLIPRECTS;
	} while (n < cmdbuf->nbox);

	return (0);
}

/*
 * Some of the R300 chips seem to be extremely touchy about the two registers
 * that are configured in r300_pacify.
 * Among the worst offenders seems to be the R300 ND (0x4E44): When userspace
 * sends a command buffer that contains only state setting commands and a
 * vertex program/parameter upload sequence, this will eventually lead to a
 * lockup, unless the sequence is bracketed by calls to r300_pacify.
 * So we should take great care to *always* call r300_pacify before
 * *anything* 3D related, and again afterwards. This is what the
 * call bracket in r300_do_cp_cmdbuf is for.
 */

/*
 * Emit the sequence to pacify R300.
 */
static __inline__ void r300_pacify(drm_radeon_private_t *dev_priv)
{
	RING_LOCALS;

	BEGIN_RING(6);
	OUT_RING(CP_PACKET0(R300_RB3D_DSTCACHE_CTLSTAT, 0));
	OUT_RING(0xa);
	OUT_RING(CP_PACKET0(0x4f18, 0));
	OUT_RING(0x3);
	OUT_RING(CP_PACKET3(RADEON_CP_NOP, 0));
	OUT_RING(0x0);
	ADVANCE_RING();
}

/*
 * Called by r300_do_cp_cmdbuf to update the internal buffer age and state.
 * The actual age emit is done by r300_do_cp_cmdbuf, which is why you must
 * be careful about how this function is called.
 */
static void r300_discard_buffer(drm_device_t *dev, drm_buf_t *buf)
{
	drm_radeon_private_t *dev_priv = dev->dev_private;
	drm_radeon_buf_priv_t *buf_priv = buf->dev_private;

	buf_priv->age = ++dev_priv->sarea_priv->last_dispatch;
	buf->pending = 1;
	buf->used = 0;
}

static int r300_scratch(drm_radeon_private_t *dev_priv,
			drm_radeon_kcmd_buffer_t *cmdbuf,
			drm_r300_cmd_header_t header)
{
	u32 *ref_age_base;
	u32 i, buf_idx, h_pending;
	RING_LOCALS;

	if (cmdbuf->bufsz < sizeof (uint64_t) +
	    header.scratch.n_bufs * sizeof (buf_idx)) {
		return (EINVAL);
	}

	if (header.scratch.reg >= 5) {
		return (EINVAL);
	}

	dev_priv->scratch_ages[header.scratch.reg] ++;

	ref_age_base = (u32 *)(uintptr_t)*((uint64_t *)(uintptr_t)cmdbuf->buf);

	cmdbuf->buf += sizeof (uint64_t);
	cmdbuf->bufsz -= sizeof (uint64_t);

	for (i = 0; i < header.scratch.n_bufs; i++) {
		buf_idx = *(u32 *)(uintptr_t)cmdbuf->buf;
		buf_idx *= 2; /* 8 bytes per buf */

		if (DRM_COPY_TO_USER(ref_age_base + buf_idx,
		    &dev_priv->scratch_ages[header.scratch.reg],
		    sizeof (u32))) {
			return (EINVAL);
		}

		if (DRM_COPY_FROM_USER(&h_pending,
		    ref_age_base + buf_idx + 1, sizeof (u32))) {
			return (EINVAL);
		}

		if (h_pending == 0) {
			return (EINVAL);
		}

		h_pending--;

		if (DRM_COPY_TO_USER(ref_age_base + buf_idx + 1,
		    &h_pending, sizeof (u32))) {
			return (EINVAL);
		}

		cmdbuf->buf += sizeof (buf_idx);
		cmdbuf->bufsz -= sizeof (buf_idx);
	}

	BEGIN_RING(2);
	OUT_RING(CP_PACKET0(RADEON_SCRATCH_REG0 + header.scratch.reg * 4, 0));
	OUT_RING(dev_priv->scratch_ages[header.scratch.reg]);
	ADVANCE_RING();

	return (0);
}

/*
 * Parses and validates a user-supplied command buffer and emits appropriate
 * commands on the DMA ring buffer.
 * Called by the ioctl handler function radeon_cp_cmdbuf.
 */
/*ARGSUSED*/
int
r300_do_cp_cmdbuf(drm_device_t *dev,
    drm_file_t *fpriv, drm_radeon_kcmd_buffer_t *cmdbuf)
{
	drm_radeon_private_t *dev_priv = dev->dev_private;
	drm_device_dma_t *dma = dev->dma;
	drm_buf_t *buf = NULL;
	int emit_dispatch_age = 0;
	int ret = 0;

	DRM_DEBUG("\n");

	/*
	 * See the comment above r300_emit_begin3d for why this call
	 * must be here, and what the cleanup gotos are for.
	 */
	r300_pacify(dev_priv);

	if (cmdbuf->nbox <= R300_SIMULTANEOUS_CLIPRECTS) {
		ret = r300_emit_cliprects(dev_priv, cmdbuf, 0);
		if (ret)
			goto cleanup;
	}

	while (cmdbuf->bufsz >= sizeof (drm_r300_cmd_header_t)) {
		int idx;
		drm_r300_cmd_header_t header;

		header.u = *(unsigned int *)(uintptr_t)cmdbuf->buf;

		cmdbuf->buf += sizeof (header);
		cmdbuf->bufsz -= sizeof (header);

		switch (header.header.cmd_type) {
		case R300_CMD_PACKET0:
			DRM_DEBUG("R300_CMD_PACKET0\n");
			ret = r300_emit_packet0(dev_priv, cmdbuf, header);
			if (ret) {
				DRM_ERROR("r300_emit_packet0 failed\n");
				goto cleanup;
			}
			break;

		case R300_CMD_VPU:
			DRM_DEBUG("R300_CMD_VPU\n");
			ret = r300_emit_vpu(dev_priv, cmdbuf, header);
			if (ret) {
				DRM_ERROR("r300_emit_vpu failed\n");
				goto cleanup;
			}
			break;

		case R300_CMD_PACKET3:
			DRM_DEBUG("R300_CMD_PACKET3\n");
			ret = r300_emit_packet3(dev_priv, cmdbuf, header);
			if (ret) {
				DRM_ERROR("r300_emit_packet3 failed\n");
				goto cleanup;
			}
			break;

		case R300_CMD_END3D:
			DRM_DEBUG("R300_CMD_END3D\n");
			/*
			 * TODO:
			 * Ideally userspace driver should not need to issue
			 * this call, i.e. the drm driver should issue it
			 * automatically and prevent lockups. In practice, we
			 * do not understand why this call is needed and what
			 * it does (except for some vague guesses that it has
			 * to do with cache coherence) and so the user space
			 * driver does it.
			 *
			 * Once we are sure which uses prevent lockups the code
			 * could be moved into the kernel and the userspace
			 * driver will not need to use this command.
			 *
			 * Note that issuing this command does not hurt anything
			 * except, possibly, performance
			 */
			r300_pacify(dev_priv);
			break;

		case R300_CMD_CP_DELAY:
			/* simple enough, we can do it here */
			DRM_DEBUG("R300_CMD_CP_DELAY\n");
			{
				int i;
				RING_LOCALS;

				BEGIN_RING(header.delay.count);
				for (i = 0; i < header.delay.count; i++)
					OUT_RING(RADEON_CP_PACKET2);
				ADVANCE_RING();
			}
			break;

		case R300_CMD_DMA_DISCARD:
			DRM_DEBUG("RADEON_CMD_DMA_DISCARD\n");
			idx = header.dma.buf_idx;
			if (idx < 0 || idx >= dma->buf_count) {
				DRM_ERROR("buffer index %d (of %d max)\n",
				    idx, dma->buf_count - 1);
				ret = EINVAL;
				goto cleanup;
			}

			buf = dma->buflist[idx];
			if (buf->filp != fpriv || buf->pending) {
				DRM_ERROR("bad buffer %p %p %d\n",
				    buf->filp, fpriv, buf->pending);
				ret = EINVAL;
				goto cleanup;
			}

			emit_dispatch_age = 1;
			r300_discard_buffer(dev, buf);
			break;

		case R300_CMD_WAIT:
			/* simple enough, we can do it here */
			DRM_DEBUG("R300_CMD_WAIT\n");
			if (header.wait.flags == 0)
				break;	/* nothing to do */

			{
				RING_LOCALS;

				BEGIN_RING(2);
				OUT_RING(CP_PACKET0(RADEON_WAIT_UNTIL, 0));
				OUT_RING((header.wait.flags & 0xf) << 14);
				ADVANCE_RING();
			}
			break;

		case R300_CMD_SCRATCH:
			DRM_DEBUG("R300_CMD_SCRATCH\n");
			ret = r300_scratch(dev_priv, cmdbuf, header);
			if (ret) {
				DRM_ERROR("r300_scratch failed\n");
				goto cleanup;
			}
			break;

		default:
			DRM_ERROR("bad cmd_type %i at %p\n",
			    header.header.cmd_type,
			    cmdbuf->buf - sizeof (header));
			ret = EINVAL;
			goto cleanup;
		}
	}

	DRM_DEBUG("END\n");

cleanup:
	r300_pacify(dev_priv);

	/*
	 * We emit the vertex buffer age here, outside the pacifier "brackets"
	 * for two reasons:
	 * (1) This may coalesce multiple age emissions into a single one and
	 * (2) more importantly, some chips lock up hard when scratch registers
	 * 		are written inside the pacifier bracket.
	 */
	if (emit_dispatch_age) {
		RING_LOCALS;

		/* Emit the vertex buffer age */
		BEGIN_RING(2);
		RADEON_DISPATCH_AGE(dev_priv->sarea_priv->last_dispatch);
		ADVANCE_RING();
	}

	COMMIT_RING();

	return (ret);
}