[Intel-gfx] [RFC 04/22] drm/i915: Add per-ring command length decode functions

[bradley.d.volkin at intel.com]

From: Brad Volkin <bradley.d.volkin at intel.com>

For commands that aren't in the parser's tables, we get the length
based on standard per-ring command encodings for specific opcode ranges.

These functions just return the bitmask and the parser will extract the
actual length value.

OTC-Tracker: AXIA-4631
Change-Id: I2729d4483931cb4aea9403fd43710c4d4e8e5e89
Signed-off-by: Brad Volkin <bradley.d.volkin at intel.com>
---
 drivers/gpu/drm/i915/i915_cmd_parser.c  | 62 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.h | 12 +++++++
 2 files changed, 74 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
index 014e661..247d530 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -137,6 +137,62 @@ static const struct drm_i915_cmd_table gen7_blt_cmds[] = {
 	{ blt_cmds, ARRAY_SIZE(blt_cmds) },
 };
 
+#define CLIENT_MASK      0xE0000000
+#define SUBCLIENT_MASK   0x18000000
+#define MI_CLIENT        0x00000000
+#define RC_CLIENT        0x60000000
+#define BC_CLIENT        0x40000000
+#define MEDIA_SUBCLIENT  0x10000000
+
+static u32 gen7_render_get_cmd_length_mask(u32 cmd_header)
+{
+	u32 client = cmd_header & CLIENT_MASK;
+	u32 subclient = cmd_header & SUBCLIENT_MASK;
+
+	if (client == MI_CLIENT)
+		return 0x3F;
+	else if (client == RC_CLIENT) {
+		if (subclient == MEDIA_SUBCLIENT)
+			return 0xFFFF;
+		else
+			return 0xFF;
+	}
+
+	DRM_DEBUG_DRIVER("CMD: Abnormal rcs cmd length! 0x%08X\n", cmd_header);
+	return 0;
+}
+
+static u32 gen7_bsd_get_cmd_length_mask(u32 cmd_header)
+{
+	u32 client = cmd_header & CLIENT_MASK;
+	u32 subclient = cmd_header & SUBCLIENT_MASK;
+
+	if (client == MI_CLIENT)
+		return 0x3F;
+	else if (client == RC_CLIENT) {
+		if (subclient == MEDIA_SUBCLIENT)
+			return 0xFFF;
+		else
+			return 0xFF;
+	}
+
+	DRM_DEBUG_DRIVER("CMD: Abnormal bsd cmd length! 0x%08X\n", cmd_header);
+	return 0;
+}
+
+static u32 gen7_blt_get_cmd_length_mask(u32 cmd_header)
+{
+	u32 client = cmd_header & CLIENT_MASK;
+
+	if (client == MI_CLIENT)
+		return 0x3F;
+	else if (client == BC_CLIENT)
+		return 0xFF;
+
+	DRM_DEBUG_DRIVER("CMD: Abnormal blt cmd length! 0x%08X\n", cmd_header);
+	return 0;
+}
+
 void i915_cmd_parser_init_ring(struct intel_ring_buffer *ring)
 {
 	if (!IS_GEN7(ring->dev))
@@ -152,18 +208,24 @@ void i915_cmd_parser_init_ring(struct intel_ring_buffer *ring)
 			ring->cmd_tables = gen7_render_cmds;
 			ring->cmd_table_count = ARRAY_SIZE(gen7_render_cmds);
 		}
+
+		ring->get_cmd_length_mask = gen7_render_get_cmd_length_mask;
 		break;
 	case VCS:
 		ring->cmd_tables = gen7_video_cmds;
 		ring->cmd_table_count = ARRAY_SIZE(gen7_video_cmds);
+		ring->get_cmd_length_mask = gen7_bsd_get_cmd_length_mask;
 		break;
 	case BCS:
 		ring->cmd_tables = gen7_blt_cmds;
 		ring->cmd_table_count = ARRAY_SIZE(gen7_blt_cmds);
+		ring->get_cmd_length_mask = gen7_blt_get_cmd_length_mask;
 		break;
 	case VECS:
 		ring->cmd_tables = hsw_vebox_cmds;
 		ring->cmd_table_count = ARRAY_SIZE(hsw_vebox_cmds);
+		/* VECS can use the same length_mask function as VCS */
+		ring->get_cmd_length_mask = gen7_bsd_get_cmd_length_mask;
 		break;
 	default:
 		DRM_DEBUG("CMD: cmd_parser_init with unknown ring: %d\n",
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 67305d3..8e71b59 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -169,6 +169,18 @@ struct  intel_ring_buffer {
 	 */
 	const struct drm_i915_cmd_table *cmd_tables;
 	int cmd_table_count;
+
+	/**
+	 * Returns the bitmask for the length field of the specified command.
+	 * Return 0 for an unrecognized/invalid command.
+	 *
+	 * If the command parser finds an entry for a command in the ring's
+	 * cmd_tables, it gets the command's length based on the table entry.
+	 * If not, it calls this function to determine the per-ring length field
+	 * encoding for the command (i.e. certain opcode ranges use certain bits
+	 * to encode the command length in the header).
+	 */
+	u32 (*get_cmd_length_mask)(u32 cmd_header);
 };
 
 static inline bool
-- 
1.8.4.4