[Intel-gfx] [PATCH] drm/i915/guc/slpc: remove unneeded clflush calls

Lucas De Marchi
2021-09-14T19:52:14Z

The clflush calls here aren't doing anything since we are not writting
something and flushing the cache lines to be visible to GuC. Here the
intention seems to be to make sure whatever GuC has written is visible
to the CPU before we read them. However a clflush from the CPU side is
the wrong instruction to use.

From code inspection on the other clflush() calls in i915/gt/uc/ these
are the only ones with this behavrior. The others are apparently making
sure what we write is visible to GuC.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
---
drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
index 65a3e7fdb2b2..2e996b77df80 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_slpc.c
@@ -108,7 +108,6 @@ static u32 slpc_get_state(struct intel_guc_slpc *slpc)

GEM_BUG_ON(!slpc->vma);

- drm_clflush_virt_range(slpc->vaddr, sizeof(u32));
data = slpc->vaddr;

return data->header.global_state;
@@ -172,8 +171,6 @@ static int slpc_query_task_state(struct intel_guc_slpc *slpc)
drm_err(&i915->drm, "Failed to query task state (%pe)\n",
ERR_PTR(ret));

- drm_clflush_virt_range(slpc->vaddr, SLPC_PAGE_SIZE_BYTES);
-
return ret;
}

--
2.32.0