drm/msm/a5xx: fix context faults during ring switch

The rptr_addr is set in the preempt_init_ring(), which is called from
a5xx_gpu_init(). It uses shadowptr() to set the address, however the
shadow_iova is not yet initialized at that time. Move the rptr_addr
setting to the a5xx_preempt_hw_init() which is called after setting the
shadow_iova, getting the correct value for the address.

Fixes: 8907afb4 ("drm/msm: Allow a5xx to mark the RPTR shadow as privileged")
Suggested-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/522640/
Link: https://lore.kernel.org/r/20230214020956.164473-5-dmitry.baryshkov@linaro.orgSigned-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/adreno/a5xx_preempt.c

@@ -207,6 +207,7 @@ void a5xx_preempt_hw_init(struct msm_gpu *gpu)
 		a5xx_gpu->preempt[i]->wptr = 0;
 		a5xx_gpu->preempt[i]->rptr = 0;
 		a5xx_gpu->preempt[i]->rbase = gpu->rb[i]->iova;
+		a5xx_gpu->preempt[i]->rptr_addr = shadowptr(a5xx_gpu, gpu->rb[i]);
 	}
 
 	/* Write a 0 to signal that we aren't switching pagetables */
@@ -257,7 +258,6 @@ static int preempt_init_ring(struct a5xx_gpu *a5xx_gpu,
 	ptr->data = 0;
 	ptr->cntl = MSM_GPU_RB_CNTL_DEFAULT | AXXX_CP_RB_CNTL_NO_UPDATE;
 
-	ptr->rptr_addr = shadowptr(a5xx_gpu, ring);
 	ptr->counter = counters_iova;
 
 	return 0;