drm/msm/a6xx: Remove unneeded GBIF unhalt

Commit e812744c ("drm: msm: a6xx: Add support for A618") added a
universal GBIF un-halt into a6xx_start(). This can cause problems for
a630 targets which do not use GBIF and might have access protection
enabled on the region now occupied by the GBIF registers.

But it turns out that we didn't need to unhalt the GBIF in this path
since the stop function already takes care of that after executing a flush
but before turning off the headswitch. We should be confident that the
GBIF is open for business when we restart the hardware.
Signed-off-by: NJordan Crouse <jcrouse@codeaurora.org>
Tested-by: NJohn Stultz <john.stultz@linaro.org>
Reviewed-by: NRob Clark <robdclark@gmail.com>
Fixes: e812744c ("drm: msm: a6xx: Add support for A618")
Signed-off-by: NRob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a6xx_gpu.c

@@ -378,18 +378,6 @@ static int a6xx_hw_init(struct msm_gpu *gpu)
 	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
 	int ret;
 
-	/*
-	 * During a previous slumber, GBIF halt is asserted to ensure
-	 * no further transaction can go through GPU before GPU
-	 * headswitch is turned off.
-	 *
-	 * This halt is deasserted once headswitch goes off but
-	 * incase headswitch doesn't goes off clear GBIF halt
-	 * here to ensure GPU wake-up doesn't fail because of
-	 * halted GPU transactions.
-	 */
-	gpu_write(gpu, REG_A6XX_GBIF_HALT, 0x0);
-
 	/* Make sure the GMU keeps the GPU on while we set it up */
 	a6xx_gmu_set_oob(&a6xx_gpu->gmu, GMU_OOB_GPU_SET);