[Intel-gfx] [PATCH] drm/i915: Fix build warning in debugfs

[Matt Roper]

i915_gem_obj_ggtt_pin() is marked as __must_check, but one callsite in
debugfs (i915_dump_lrc) was not checking the return value.  Add the
necessary check and make the debugfs node print something
semi-reasonable if we were to fail to pin.

I believe there's already in-progress discussion on the mailing list
about how this area of the code is going to be reworked in general.  But
in the meantime, this is just a quick fix to shut up the compiler
warning.

This warning was added in commit:

        commit dcb4c12a687710ab745c2cdee8298c3e97f6f707
        Author: Oscar Mateo <oscar.mateo at intel.com>
        Date:   Thu Nov 13 10:28:10 2014 +0000

            drm/i915/bdw: Pin the context backing objects to GGTT on-demand

Cc: Oscar Mateo <oscar.mateo at intel.com>
Cc: Thomas Daniel <thomas.daniel at intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 7ea3843..9934ec9 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1801,10 +1801,15 @@ static int i915_dump_lrc(struct seq_file *m, void *unused)
 			if (ctx_obj) {
 				struct page *page;
 				uint32_t *reg_state;
-				int j;
+				int ret, j;
 
-				i915_gem_obj_ggtt_pin(ctx_obj,
+				ret = i915_gem_obj_ggtt_pin(ctx_obj,
 						GEN8_LR_CONTEXT_ALIGN, 0);
+				if (ret) {
+					seq_printf(m, "CONTEXT: %s (unavail)\n",
+						   ring->name);
+					continue;
+				}
 
 				page = i915_gem_object_get_page(ctx_obj, 1);
 				reg_state = kmap_atomic(page);
-- 
1.8.5.1