On Wed, Mar 16, 2016 at 01:52:10PM +0100, Michał Winiarski wrote:
> Test description suggested that all platforms were testing qword writes,
> while in fact only gen4-gen5 did.
> 
> v2: Test dword/qword writes for all available platforms
> 
> Cc: Chris Wilson <ch...@chris-wilson.co.uk>
> Signed-off-by: Michał Winiarski <michal.winiar...@intel.com>
> ---
>  tests/gem_pipe_control_store_loop.c | 49 
> +++++++++++++++++++++++++------------
>  1 file changed, 33 insertions(+), 16 deletions(-)
> 
> diff --git a/tests/gem_pipe_control_store_loop.c 
> b/tests/gem_pipe_control_store_loop.c
> index a155ad1..cab3ed5 100644
> --- a/tests/gem_pipe_control_store_loop.c
> +++ b/tests/gem_pipe_control_store_loop.c
> @@ -26,7 +26,7 @@
>   */
>  
>  /*
> - * Testcase: (TLB-)Coherency of pipe_control QW writes
> + * Testcase: (TLB-)Coherency of pipe_control writes
>   *
>   * Writes a counter-value into an always newly allocated target bo (by 
> disabling
>   * buffer reuse). Decently trashes on tlb inconsistencies, too.
> @@ -43,7 +43,7 @@
>  #include "drm.h"
>  #include "intel_bufmgr.h"
>  
> -IGT_TEST_DESCRIPTION("Test (TLB-)Coherency of pipe_control QW writes.");
> +IGT_TEST_DESCRIPTION("Test (TLB-)Coherency of pipe_control writes.");
>  
>  static drm_intel_bufmgr *bufmgr;
>  struct intel_batchbuffer *batch;
> @@ -60,13 +60,20 @@ uint32_t devid;
>  #define   PIPE_CONTROL_CS_STALL      (1<<20)
>  #define   PIPE_CONTROL_GLOBAL_GTT (1<<2) /* in addr dword */
>  
> +#define PIPE_CONTROL_STATE_BUFFER_REUSED     (1 << 0)
> +#define PIPE_CONTROL_STATE_QWORD_WRITE               (1 << 1)
> +#define PIPE_CONTROL_STATE_ALL_FLAGS (PIPE_CONTROL_STATE_BUFFER_REUSED | \
> +                                   PIPE_CONTROL_STATE_QWORD_WRITE)

Let's not use PIPE_CONTROL for test flags. That was very confusing!

> +
>  /* Like the store dword test, but we create new command buffers each time */
>  static void
> -store_pipe_control_loop(bool preuse_buffer)
> +store_pipe_control_loop(uint32_t flags)
>  {
>       int i, val = 0;
>       uint32_t *buf;
>       drm_intel_bo *target_bo;
> +     const bool preuse_buffer = flags & PIPE_CONTROL_STATE_BUFFER_REUSED;
> +     const bool qword_write = flags & PIPE_CONTROL_STATE_QWORD_WRITE;
>  
>       for (i = 0; i < SLOW_QUICK(0x10000, 4); i++) {
>               /* we want to check tlb consistency of the pipe_control target,
> @@ -98,15 +105,16 @@ store_pipe_control_loop(bool preuse_buffer)
>                * creating new batchbuffers - with buffer reuse disabled, the
>                * support code will do that for us. */
>               if (batch->gen >= 8) {
> -                     BEGIN_BATCH(4, 1);
> -                     OUT_BATCH(GFX_OP_PIPE_CONTROL + 1);
> +                     BEGIN_BATCH(4 + qword_write, 1);
> +                     OUT_BATCH(GFX_OP_PIPE_CONTROL + 1 + qword_write);
>                       OUT_BATCH(PIPE_CONTROL_WRITE_IMMEDIATE);
>                       OUT_RELOC_FENCED(target_bo,
>                            I915_GEM_DOMAIN_INSTRUCTION, 
> I915_GEM_DOMAIN_INSTRUCTION,
>                            PIPE_CONTROL_GLOBAL_GTT);
>                       OUT_BATCH(val); /* write data */
> +                     if (qword_write)
> +                             OUT_BATCH(~val); /* high dword */
>                       ADVANCE_BATCH();

Let's put a MI_NOOP | 0xabcd here to catch if the HW is reading past the
end of the packet and writing the upper dword anyway.

> -
>               } else if (batch->gen >= 6) {
>                       /* work-around hw issue, see 
> intel_emit_post_sync_nonzero_flush
>                        * in mesa sources. */
> @@ -118,24 +126,27 @@ store_pipe_control_loop(bool preuse_buffer)
>                       OUT_BATCH(0); /* write data */
>                       ADVANCE_BATCH();
>  
> -                     BEGIN_BATCH(4, 1);
> -                     OUT_BATCH(GFX_OP_PIPE_CONTROL);
> +                     BEGIN_BATCH(4 + qword_write, 1);
> +                     OUT_BATCH(GFX_OP_PIPE_CONTROL + qword_write);
>                       OUT_BATCH(PIPE_CONTROL_WRITE_IMMEDIATE);
>                       OUT_RELOC(target_bo,
>                            I915_GEM_DOMAIN_INSTRUCTION, 
> I915_GEM_DOMAIN_INSTRUCTION, 
>                            PIPE_CONTROL_GLOBAL_GTT);
>                       OUT_BATCH(val); /* write data */
> +                     if (qword_write)
> +                             OUT_BATCH(~val); /* high dword */
>                       ADVANCE_BATCH();
>               } else if (batch->gen >= 4) {
> -                     BEGIN_BATCH(4, 1);
> +                     BEGIN_BATCH(3 + qword_write, 1);
>                       OUT_BATCH(GFX_OP_PIPE_CONTROL | PIPE_CONTROL_WC_FLUSH |
>                                       PIPE_CONTROL_TC_FLUSH |
> -                                     PIPE_CONTROL_WRITE_IMMEDIATE | 2);
> +                                     PIPE_CONTROL_WRITE_IMMEDIATE | (1 + 
> qword_write));

Ideally we should remove the extra flushes that are not required for
emitting the write. Part of the test is that the kernel is emitting
adequate flushes for a standalone pipecontrol batch.

>                       OUT_RELOC(target_bo,
>                               I915_GEM_DOMAIN_INSTRUCTION, 
> I915_GEM_DOMAIN_INSTRUCTION,
>                               PIPE_CONTROL_GLOBAL_GTT);

Fiddle sticks. Get rid of the libdrm layer so that I can control the
placement of the batch completely to double check that the kernel w/a
happens with the batch and not by random happenstance because of
intel_batchbuffer.c

>                       OUT_BATCH(val);
> -                     OUT_BATCH(0xdeadbeef);
> +                     if (qword_write)
> +                             OUT_BATCH(~val); /* high dword */
>                       ADVANCE_BATCH();
>               }
>  
> @@ -145,6 +156,8 @@ store_pipe_control_loop(bool preuse_buffer)
>  
>               buf = target_bo->virtual;
>               igt_assert(buf[0] == val);
> +             if (qword_write)
> +                     igt_assert(buf[1] == ~val);

else
        igt_assert_eq_u32(buf[1], 0);

We also want to test CPU coherency, since these instructions are
advertising as being compatable with snooped writes.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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