The patch below does not apply to the 3.18-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From d474ea7e52cbaaae22711d857949ba6018562c29 Mon Sep 17 00:00:00 2001
From: Alex Deucher <[email protected]>
Date: Mon, 5 Jan 2015 19:54:50 -0500
Subject: [PATCH] drm/radeon: fix VM flush on SI (v3)
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

We need to wait for the GPUVM flush to complete.  There
was some confusion as to how this mechanism was supposed
to work.  The operation is not atomic.  For GPU initiated
invalidations you need to read back a VM register to
introduce enough latency for the update to complete.

v2: drop gart changes
v3: just read back rather than polling

Reviewed-by: Christian König <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>
Cc: [email protected]

diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index 60df444bd075..5d89b874a1a2 100644
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -5057,6 +5057,16 @@ void si_vm_flush(struct radeon_device *rdev, struct 
radeon_ring *ring,
        radeon_ring_write(ring, 0);
        radeon_ring_write(ring, 1 << vm_id);
 
+       /* wait for the invalidate to complete */
+       radeon_ring_write(ring, PACKET3(PACKET3_WAIT_REG_MEM, 5));
+       radeon_ring_write(ring, (WAIT_REG_MEM_FUNCTION(0) |  /* always */
+                                WAIT_REG_MEM_ENGINE(0))); /* me */
+       radeon_ring_write(ring, VM_INVALIDATE_REQUEST >> 2);
+       radeon_ring_write(ring, 0);
+       radeon_ring_write(ring, 0); /* ref */
+       radeon_ring_write(ring, 0); /* mask */
+       radeon_ring_write(ring, 0x20); /* poll interval */
+
        /* sync PFP to ME, otherwise we might get invalid PFP reads */
        radeon_ring_write(ring, PACKET3(PACKET3_PFP_SYNC_ME, 0));
        radeon_ring_write(ring, 0x0);
diff --git a/drivers/gpu/drm/radeon/si_dma.c b/drivers/gpu/drm/radeon/si_dma.c
index f5cc777e1c5f..aa7b872b2c43 100644
--- a/drivers/gpu/drm/radeon/si_dma.c
+++ b/drivers/gpu/drm/radeon/si_dma.c
@@ -206,6 +206,14 @@ void si_dma_vm_flush(struct radeon_device *rdev, struct 
radeon_ring *ring,
        radeon_ring_write(ring, DMA_PACKET(DMA_PACKET_SRBM_WRITE, 0, 0, 0, 0));
        radeon_ring_write(ring, (0xf << 16) | (VM_INVALIDATE_REQUEST >> 2));
        radeon_ring_write(ring, 1 << vm_id);
+
+       /* wait for invalidate to complete */
+       radeon_ring_write(ring, DMA_PACKET(DMA_PACKET_POLL_REG_MEM, 0, 0, 0, 
0));
+       radeon_ring_write(ring, VM_INVALIDATE_REQUEST);
+       radeon_ring_write(ring, 0xff << 16); /* retry */
+       radeon_ring_write(ring, 1 << vm_id); /* mask */
+       radeon_ring_write(ring, 0); /* value */
+       radeon_ring_write(ring, (0 << 28) | 0x20); /* func(always) | poll 
interval */
 }
 
 /**
diff --git a/drivers/gpu/drm/radeon/sid.h b/drivers/gpu/drm/radeon/sid.h
index 4069be89e585..84999242c747 100644
--- a/drivers/gpu/drm/radeon/sid.h
+++ b/drivers/gpu/drm/radeon/sid.h
@@ -1632,6 +1632,23 @@
 #define        PACKET3_MPEG_INDEX                              0x3A
 #define        PACKET3_COPY_DW                                 0x3B
 #define        PACKET3_WAIT_REG_MEM                            0x3C
+#define                WAIT_REG_MEM_FUNCTION(x)                ((x) << 0)
+                /* 0 - always
+                * 1 - <
+                * 2 - <=
+                * 3 - ==
+                * 4 - !=
+                * 5 - >=
+                * 6 - >
+                */
+#define                WAIT_REG_MEM_MEM_SPACE(x)               ((x) << 4)
+                /* 0 - reg
+                * 1 - mem
+                */
+#define                WAIT_REG_MEM_ENGINE(x)                  ((x) << 8)
+                /* 0 - me
+                * 1 - pfp
+                */
 #define        PACKET3_MEM_WRITE                               0x3D
 #define        PACKET3_COPY_DATA                               0x40
 #define        PACKET3_CP_DMA                                  0x41
@@ -1835,6 +1852,7 @@
 #define        DMA_PACKET_TRAP                                   0x7
 #define        DMA_PACKET_SRBM_WRITE                             0x9
 #define        DMA_PACKET_CONSTANT_FILL                          0xd
+#define        DMA_PACKET_POLL_REG_MEM                           0xe
 #define        DMA_PACKET_NOP                                    0xf
 
 #define VCE_STATUS                                     0x20004

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