[Intel-gfx] [PATCH 43/48] drm/i915: Warn on gem_pin usage

[Ben Widawsky]

The pin IOCTL is leftover from the days of yore. It allows you to take a
buffer, pin it, and receive the offset of that buffer. The IOCTL does
not support the newer notion of contexts and VM, and therefore is not
suitable for modern usage.

The unsolvable problem is, "which address space do I pin this in?"

As there are still mechanisms to do things only with the GGTT, and this
could potentially have benefit as workarounds, leave it in place, but
provide a warning to users.

Request-to-not-deprecate-by: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_gem.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index f7114ae..a03c262 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3950,6 +3950,8 @@ i915_gem_pin_ioctl(struct drm_device *dev, void *data,
 			goto out;
 	}
 
+	if (USES_FULL_PPGTT(dev))
+		DRM_DEBUG_DRIVER("Pinning with full PPGTT is not recommended\n");
 	obj->user_pin_count++;
 	obj->pin_filp = file;
 
-- 
1.8.4.2