[PATCH 08/21] drm/etnaviv: add 'sync point' support

[Christian Gmeiner]

In order to support performance counters in a sane way we need to provide
a method to sync the GPU with the CPU. The GPU can process multpile command
buffers/events per irq. With the help of a 'sync point' we can trigger an event
and stop the GPU/FE immediately. When the CPU is done with is processing it
simply needs to restart the FE and the GPU will continue.

Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_buffer.c | 36 ++++++++++++++++++++++++++++++++
 drivers/gpu/drm/etnaviv/etnaviv_drv.h    |  1 +
 drivers/gpu/drm/etnaviv/etnaviv_gpu.c    | 14 +++++++++++++
 drivers/gpu/drm/etnaviv/etnaviv_gpu.h    |  2 ++
 4 files changed, 53 insertions(+)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
index ed9588f..9e7098e 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
@@ -250,6 +250,42 @@ void etnaviv_buffer_end(struct etnaviv_gpu *gpu)
 	}
 }
 
+/* Append a 'sync point' to the ring buffer. */
+void etnaviv_sync_point_queue(struct etnaviv_gpu *gpu, unsigned int event)
+{
+	struct etnaviv_cmdbuf *buffer = gpu->buffer;
+	unsigned int waitlink_offset = buffer->user_size - 16;
+	u32 dwords, target;
+
+	/*
+	 * We need at most 3 dwords in the return target:
+	 * 1 event + 1 end + 1 wait + 1 link.
+	 */
+	dwords = 4;
+	target = etnaviv_buffer_reserve(gpu, buffer, dwords);
+
+	/* Signal sync point event */
+	CMD_LOAD_STATE(buffer, VIVS_GL_EVENT, VIVS_GL_EVENT_EVENT_ID(event) |
+		       VIVS_GL_EVENT_FROM_PE);
+
+	/* Stop the FE to 'pause' the GPU */
+	CMD_END(buffer);
+
+	/* Append waitlink */
+	CMD_WAIT(buffer);
+	CMD_LINK(buffer, 2, etnaviv_cmdbuf_get_va(buffer) +
+			    buffer->user_size - 4);
+
+	/*
+	 * Kick off the 'sync point' command by replacing the previous
+	 * WAIT with a link to the address in the ring buffer.
+	 */
+	etnaviv_buffer_replace_wait(buffer, waitlink_offset,
+				    VIV_FE_LINK_HEADER_OP_LINK |
+				    VIV_FE_LINK_HEADER_PREFETCH(dwords),
+				    target);
+}
+
 /* Append a command buffer to the ring buffer. */
 void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, unsigned int event,
 	struct etnaviv_cmdbuf *cmdbuf)
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
index 058389f..f6cdd69 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
@@ -101,6 +101,7 @@ int etnaviv_gem_new_userptr(struct drm_device *dev, struct drm_file *file,
 u16 etnaviv_buffer_init(struct etnaviv_gpu *gpu);
 u16 etnaviv_buffer_config_mmuv2(struct etnaviv_gpu *gpu, u32 mtlb_addr, u32 safe_addr);
 void etnaviv_buffer_end(struct etnaviv_gpu *gpu);
+void etnaviv_sync_point_queue(struct etnaviv_gpu *gpu, unsigned int event);
 void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, unsigned int event,
 	struct etnaviv_cmdbuf *cmdbuf);
 void etnaviv_validate_init(void);
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
index 037087e..803fcf4 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
@@ -25,6 +25,7 @@
 #include "etnaviv_gpu.h"
 #include "etnaviv_gem.h"
 #include "etnaviv_mmu.h"
+#include "etnaviv_perfmon.h"
 #include "common.xml.h"
 #include "state.xml.h"
 #include "state_hi.xml.h"
@@ -1349,6 +1350,7 @@ int etnaviv_gpu_submit(struct etnaviv_gpu *gpu,
 	}
 
 	gpu->event[event].fence = fence;
+	gpu->event[event].sync_point = NULL;
 	submit->fence = dma_fence_get(fence);
 	gpu->active_fence = submit->fence->seqno;
 
@@ -1394,6 +1396,15 @@ int etnaviv_gpu_submit(struct etnaviv_gpu *gpu,
 	return ret;
 }
 
+static void etnaviv_process_sync_point(struct etnaviv_gpu *gpu,
+	struct etnaviv_event *event)
+{
+	u32 addr = gpu_read(gpu, VIVS_FE_DMA_ADDRESS);
+
+	event->sync_point(gpu, event);
+	etnaviv_gpu_start_fe(gpu, addr + 2, 2);
+}
+
 /*
  * Init/Cleanup:
  */
@@ -1440,6 +1451,9 @@ static irqreturn_t irq_handler(int irq, void *data)
 
 			dev_dbg(gpu->dev, "event %u\n", event);
 
+			if (gpu->event[event].sync_point)
+				etnaviv_process_sync_point(gpu, &gpu->event[event]);
+
 			fence = gpu->event[event].fence;
 			gpu->event[event].fence = NULL;
 			dma_fence_signal(fence);
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
index 689cb8f..fee6ed9 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.h
@@ -90,6 +90,8 @@ struct etnaviv_chip_identity {
 struct etnaviv_event {
 	bool used;
 	struct dma_fence *fence;
+
+	void (*sync_point)(struct etnaviv_gpu *gpu, struct etnaviv_event *event);
 };
 
 struct etnaviv_cmdbuf_suballoc;
-- 
2.9.4