drm/i915: remove duplicate names for the render ring INSTDONE register

We use 3 different names to refer to the same render ring INSTDONE
register. This can be confusing when comparing two parts of the code
accessing the register via different names. Although the GEN4 version's
layout is different, we treat it the same way as the GEN7+ version, in
that we simply read it out during error capture. So remove the
duplicates and leave a comment about the GEN4 difference.

Note that there is also a GEN2 version of this register, but that's on a
different address so not handled in this patch.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gpu_error.c

@@ -1390,10 +1390,10 @@ void i915_get_extra_instdone(struct drm_device *dev, uint32_t *instdone)
 	if (IS_GEN2(dev) || IS_GEN3(dev))
 		instdone[0] = I915_READ(INSTDONE);
 	else if (IS_GEN4(dev) || IS_GEN5(dev) || IS_GEN6(dev)) {
-		instdone[0] = I915_READ(INSTDONE_I965);
+		instdone[0] = I915_READ(RING_INSTDONE(RENDER_RING_BASE));
 		instdone[1] = I915_READ(INSTDONE1);
 	} else if (INTEL_INFO(dev)->gen >= 7) {
-		instdone[0] = I915_READ(GEN7_INSTDONE_1);
+		instdone[0] = I915_READ(RING_INSTDONE(RENDER_RING_BASE));
 		instdone[1] = I915_READ(GEN7_SC_INSTDONE);
 		instdone[2] = I915_READ(GEN7_SAMPLER_INSTDONE);
 		instdone[3] = I915_READ(GEN7_ROW_INSTDONE);

drivers/gpu/drm/i915/i915_reg.h

@@ -1593,14 +1593,16 @@ enum skl_disp_power_wells {
 #endif
 #define IPEIR_I965	0x02064
 #define IPEHR_I965	0x02068
-#define INSTDONE_I965	0x0206c
-#define GEN7_INSTDONE_1		0x0206c
 #define GEN7_SC_INSTDONE	0x07100
 #define GEN7_SAMPLER_INSTDONE	0x0e160
 #define GEN7_ROW_INSTDONE	0x0e164
 #define I915_NUM_INSTDONE_REG	4
 #define RING_IPEIR(base)	((base)+0x64)
 #define RING_IPEHR(base)	((base)+0x68)
+/*
+ * On GEN4, only the render ring INSTDONE exists and has a different
+ * layout than the GEN7+ version.
+ */
 #define RING_INSTDONE(base)	((base)+0x6c)
 #define RING_INSTPS(base)	((base)+0x70)
 #define RING_DMA_FADD(base)	((base)+0x78)