drm/i915: print a message when we detect an early Haswell SDV

The machines that fall in this category are the SDVs that have a PCI
ID starting with 0x0C. These are very early pre-production machines
and may not fully work. Other Haswell SDVs have PCI IDs that match the
real Haswell machines and we expect them to work better.

Even though they have problems, they still mostly work so I don't see
a reason to refuse loading our driver. But I do see a reason to reject
bug reports from these machines, so the message should help the bug
triagers.

As far as I know, we don't implement some workarounds that are
specific to these machines and suspend/resume may not work on most of
them, but besides this, they may work.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61508
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_dma.c

@@ -1488,6 +1488,14 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 
 	i915_dump_device_info(dev_priv);
 
+	/* Not all pre-production machines fall into this category, only the
+	 * very first ones. Almost everything should work, except for maybe
+	 * suspend/resume. And we don't implement workarounds that affect only
+	 * pre-production machines. */
+	if (IS_HSW_EARLY_SDV(dev))
+		DRM_INFO("This is an early pre-production Haswell machine. "
+			 "It may not be fully functional.\n");
+
 	if (i915_get_bridge_dev(dev)) {
 		ret = -EIO;
 		goto free_priv;

drivers/gpu/drm/i915/i915_drv.h

@@ -1511,6 +1511,8 @@ struct drm_i915_file_private {
 #define IS_VALLEYVIEW(dev)	(INTEL_INFO(dev)->is_valleyview)
 #define IS_HASWELL(dev)	(INTEL_INFO(dev)->is_haswell)
 #define IS_MOBILE(dev)		(INTEL_INFO(dev)->is_mobile)
+#define IS_HSW_EARLY_SDV(dev)	(IS_HASWELL(dev) && \
+				 ((dev)->pci_device & 0xFF00) == 0x0C00)
 #define IS_ULT(dev)		(IS_HASWELL(dev) && \
 				 ((dev)->pci_device & 0xFF00) == 0x0A00)