From 3dbf26ed7b9b40a8cb008ab9ad25703363af815d Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Sat, 26 Aug 2017 14:56:20 +0100
Subject: [PATCH] drm/i915: Don't use GPU relocations prior to cmdparser stalls
Git-commit: 3dbf26ed7b9b40a8cb008ab9ad25703363af815d
Patch-mainline: v4.15-rc1
References: FATE#322643 bsc#1055900

If we are using the cmdparser, we will have to copy the batch and so
stall for the relocations. Rather than prolong that stall by adding more
relocation requests, just use CPU relocations and do the stall upfront.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170826135620.25949-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -268,6 +268,11 @@ static inline u64 gen8_noncanonical_addr
 	return address & GENMASK_ULL(GEN8_HIGH_ADDRESS_BIT, 0);
 }
 
+static inline bool eb_use_cmdparser(const struct i915_execbuffer *eb)
+{
+	return eb->engine->needs_cmd_parser && eb->batch_len;
+}
+
 static int eb_create(struct i915_execbuffer *eb)
 {
 	if (!(eb->args->flags & I915_EXEC_HANDLE_LUT)) {
@@ -1163,6 +1168,10 @@ static u32 *reloc_gpu(struct i915_execbu
 	if (unlikely(!cache->rq)) {
 		int err;
 
+		/* If we need to copy for the cmdparser, we will stall anyway */
+		if (eb_use_cmdparser(eb))
+			return ERR_PTR(-EWOULDBLOCK);
+
 		err = __reloc_gpu_alloc(eb, vma, len);
 		if (unlikely(err))
 			return ERR_PTR(err);
@@ -2303,7 +2312,7 @@ i915_gem_do_execbuffer(struct drm_device
 		goto err_vma;
 	}
 
-	if (eb.engine->needs_cmd_parser && eb.batch_len) {
+	if (eb_use_cmdparser(&eb)) {
 		struct i915_vma *vma;
 
 		vma = eb_parse(&eb, drm_is_current_master(file));