Revert "accel/ivpu: Use cached buffers for FW loading"

This reverts commit 645d6945.

The commit cause issues with memory access from the device side.
Switch back to write-combined memory mappings until the issues
will be properly addressed.

Add extra wmb() needed when boot_params->save_restore_ret_address() is
modified.
Reviewed-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231017121353.532466-1-stanislaw.gruszka@linux.intel.com

drivers/accel/ivpu/ivpu_fw.c

@@ -220,8 +220,7 @@ static int ivpu_fw_mem_init(struct ivpu_device *vdev)
 	if (ret)
 		return ret;
 
-	fw->mem = ivpu_bo_alloc_internal(vdev, fw->runtime_addr, fw->runtime_size,
-					 DRM_IVPU_BO_CACHED | DRM_IVPU_BO_NOSNOOP);
+	fw->mem = ivpu_bo_alloc_internal(vdev, fw->runtime_addr, fw->runtime_size, DRM_IVPU_BO_WC);
 	if (!fw->mem) {
 		ivpu_err(vdev, "Failed to allocate firmware runtime memory\n");
 		return -ENOMEM;
@@ -331,7 +330,7 @@ int ivpu_fw_load(struct ivpu_device *vdev)
 		memset(start, 0, size);
 	}
 
-	clflush_cache_range(fw->mem->kvaddr, fw->mem->base.size);
+	wmb(); /* Flush WC buffers after writing fw->mem */
 
 	return 0;
 }
@@ -433,7 +432,7 @@ void ivpu_fw_boot_params_setup(struct ivpu_device *vdev, struct vpu_boot_params
 	if (!ivpu_fw_is_cold_boot(vdev)) {
 		boot_params->save_restore_ret_address = 0;
 		vdev->pm->is_warmboot = true;
-		clflush_cache_range(vdev->fw->mem->kvaddr, SZ_4K);
+		wmb(); /* Flush WC buffers after writing save_restore_ret_address */
 		return;
 	}
 
@@ -495,7 +494,7 @@ void ivpu_fw_boot_params_setup(struct ivpu_device *vdev, struct vpu_boot_params
 	boot_params->punit_telemetry_sram_size = ivpu_hw_reg_telemetry_size_get(vdev);
 	boot_params->vpu_telemetry_enable = ivpu_hw_reg_telemetry_enable_get(vdev);
 
-	clflush_cache_range(vdev->fw->mem->kvaddr, SZ_4K);
+	wmb(); /* Flush WC buffers after writing bootparams */
 
 	ivpu_fw_boot_params_print(vdev, boot_params);
 }

drivers/accel/ivpu/ivpu_gem.h

@@ -8,8 +8,6 @@
 #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;
@@ -85,9 +83,6 @@ 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;
 }