drm/i915: Compute the HWS offsets explicitly

Simplify by using sizeof(u32) to convert from the index inside the HWSP
to the byte offset. This has the advantage of not only being shorter
(and so not upsetting checkpatch!) but that it matches use where we are
writing to byte addresses using other commands than MI_STORE_DWORD_IMM.

v2: Drop the now superfluous MI_STORE_DWORD_INDEX_SHIFT, it appears to
be a local invention so keeping it after the final use does not help to
clarify the GPU instruction.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190125120005.25191-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_gpu_commands.h

@@ -112,7 +112,6 @@
 #define   MI_MEM_VIRTUAL	(1 << 22) /* 945,g33,965 */
 #define   MI_USE_GGTT		(1 << 22) /* g4x+ */
 #define MI_STORE_DWORD_INDEX	MI_INSTR(0x21, 1)
-#define   MI_STORE_DWORD_INDEX_SHIFT 2
 /*
  * Official intel docs are somewhat sloppy concerning MI_LOAD_REGISTER_IMM:
  * - Always issue a MI_NOOP _before_ the MI_LOAD_REGISTER_IMM - otherwise hw

drivers/gpu/drm/i915/intel_guc_submission.c

@@ -666,7 +666,7 @@ static void complete_preempt_context(struct intel_engine_cs *engine)
 	execlists_unwind_incomplete_requests(execlists);
 
 	wait_for_guc_preempt_report(engine);
-	intel_write_status_page(engine, I915_GEM_HWS_PREEMPT_INDEX, 0);
+	intel_write_status_page(engine, I915_GEM_HWS_PREEMPT, 0);
 }
 
 /**
@@ -824,7 +824,7 @@ static void guc_submission_tasklet(unsigned long data)
 	}
 
 	if (execlists_is_active(execlists, EXECLISTS_ACTIVE_PREEMPT) &&
-	    intel_read_status_page(engine, I915_GEM_HWS_PREEMPT_INDEX) ==
+	    intel_read_status_page(engine, I915_GEM_HWS_PREEMPT) ==
 	    GUC_PREEMPT_FINISHED)
 		complete_preempt_context(engine);
 

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -716,11 +716,11 @@ intel_write_status_page(struct intel_engine_cs *engine, int reg, u32 value)
  * The area from dword 0x30 to 0x3ff is available for driver usage.
  */
 #define I915_GEM_HWS_INDEX		0x30
-#define I915_GEM_HWS_INDEX_ADDR (I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT)
-#define I915_GEM_HWS_PREEMPT_INDEX	0x32
-#define I915_GEM_HWS_PREEMPT_ADDR (I915_GEM_HWS_PREEMPT_INDEX << MI_STORE_DWORD_INDEX_SHIFT)
-#define I915_GEM_HWS_SCRATCH_INDEX	0x40
-#define I915_GEM_HWS_SCRATCH_ADDR (I915_GEM_HWS_SCRATCH_INDEX << MI_STORE_DWORD_INDEX_SHIFT)
+#define I915_GEM_HWS_INDEX_ADDR		(I915_GEM_HWS_INDEX * sizeof(u32))
+#define I915_GEM_HWS_PREEMPT		0x32
+#define I915_GEM_HWS_PREEMPT_ADDR	(I915_GEM_HWS_PREEMPT * sizeof(u32))
+#define I915_GEM_HWS_SCRATCH		0x40
+#define I915_GEM_HWS_SCRATCH_ADDR	(I915_GEM_HWS_SCRATCH * sizeof(u32))
 
 #define I915_HWS_CSB_BUF0_INDEX		0x10
 #define I915_HWS_CSB_WRITE_INDEX	0x1f