[PATCH 1/2] Guc: fallback to memcpy

[Sagar Arun Kamble]

From: Changbin Du <changbin.du at intel.com>

Not sure whether the clflush is mandatory.

Signed-off-by: Changbin Du <changbin.du at intel.com>
---
 drivers/gpu/drm/i915/intel_guc_log.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c
index 2ffc966..2ec3616 100644
--- a/drivers/gpu/drm/i915/intel_guc_log.c
+++ b/drivers/gpu/drm/i915/intel_guc_log.c
@@ -250,6 +250,16 @@ static unsigned int guc_get_log_buffer_size(enum guc_log_buffer_type type)
 	return 0;
 }
 
+static void guc_copy_log_buffer(void *dst, void *src, unsigned long len)
+{
+	if (likely(i915_can_memcpy_from_wc(dst, src, len)))
+		i915_memcpy_from_wc(dst, src, len);
+	else {
+		drm_clflush_virt_range(src, len);
+		memcpy(dst, src, len);
+	}
+}
+
 static void guc_read_update_log_buffer(struct intel_guc *guc)
 {
 	unsigned int buffer_size, read_offset, write_offset, bytes_to_copy, full_cnt;
@@ -323,12 +333,12 @@ static void guc_read_update_log_buffer(struct intel_guc *guc)
 
 		/* Just copy the newly written data */
 		if (read_offset > write_offset) {
-			i915_memcpy_from_wc(dst_data, src_data, write_offset);
+			guc_copy_log_buffer(dst_data, src_data, write_offset);
 			bytes_to_copy = buffer_size - read_offset;
 		} else {
 			bytes_to_copy = write_offset - read_offset;
 		}
-		i915_memcpy_from_wc(dst_data + read_offset,
+		guc_copy_log_buffer(dst_data + read_offset,
 				    src_data + read_offset, bytes_to_copy);
 
 		src_data += buffer_size;
@@ -520,15 +530,6 @@ int intel_guc_log_create(struct intel_guc *guc)
 		GUC_LOG_ISR_PAGES + 1 +
 		GUC_LOG_CRASH_PAGES + 1) << PAGE_SHIFT;
 
-	/* We require SSE 4.1 for fast reads from the GuC log buffer and
-	 * it should be present on the chipsets supporting GuC based
-	 * submisssions.
-	 */
-	if (WARN_ON(!i915_has_memcpy_from_wc())) {
-		ret = -EINVAL;
-		goto err;
-	}
-
 	vma = intel_guc_allocate_vma(guc, size);
 	if (IS_ERR(vma)) {
 		ret = PTR_ERR(vma);
-- 
1.9.1