accel/ivpu: Use cached buffers for FW loading

Create buffers with cache coherency on the CPU side (write-back) while
disabling snooping on the VPU side. These buffers require an explicit
cache flush after each CPU-side modification.

Configuring pages as write-combined may introduce significant delays,
potentially taking hundreds of milliseconds for 64 MB buffers.

Added internal DRM_IVPU_BO_NOSNOOP mask which disables snooping on the
VPU side. Allocate FW runtime memory buffer (64 MB) as cached with
snooping-disabled.

This fixes random long FW loading times and boot params memory
corruption on warmboot (due to missed wmb).

Fixes: 02d5b0aacd05 ("accel/ivpu: Implement firmware parsing and booting")
Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230926120943.GD846747@linux.intel.com

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/accel/ivpu/ivpu_gem.h b/drivers/accel/ivpu/ivpu_gem.h
index 6b0ceda5f253..f4130586ff1b 100644
--- a/drivers/accel/ivpu/ivpu_gem.h
+++ b/drivers/accel/ivpu/ivpu_gem.h
@@ -8,6 +8,8 @@
 #include <drm/drm_gem.h>
 #include <drm/drm_mm.h>
 
+#define DRM_IVPU_BO_NOSNOOP       0x10000000
+
 struct dma_buf;
 struct ivpu_bo_ops;
 struct ivpu_file_priv;
@@ -83,6 +85,9 @@ static inline u32 ivpu_bo_cache_mode(struct ivpu_bo *bo)
 
 static inline bool ivpu_bo_is_snooped(struct ivpu_bo *bo)
 {
+	if (bo->flags & DRM_IVPU_BO_NOSNOOP)
+		return false;
+
 	return ivpu_bo_cache_mode(bo) == DRM_IVPU_BO_CACHED;
 }