drm/radeon/kms: balance asic_reset functions

First, we were calling mc_stop() at the top of the function
which turns off all MC (memory controller) clients,
then checking if the GPU is idle.  If it was idle we
returned without re-enabling the MC clients which would
lead to a blank screen, etc.  This patch checks if the
GPU is idle before calling mc_stop().

Second, if the reset failed, we were returning without
re-enabling the MC clients.  This patch re-enables
the MC clients before returning regardless of whether
the reset was successful or not.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/r100.c

@@ -2086,12 +2086,13 @@ int r100_asic_reset(struct radeon_device *rdev)
 {
 	struct r100_mc_save save;
 	u32 status, tmp;
+	int ret = 0;
 
-	r100_mc_stop(rdev, &save);
 	status = RREG32(R_000E40_RBBM_STATUS);
 	if (!G_000E40_GUI_ACTIVE(status)) {
 		return 0;
 	}
+	r100_mc_stop(rdev, &save);
 	status = RREG32(R_000E40_RBBM_STATUS);
 	dev_info(rdev->dev, "(%s:%d) RBBM_STATUS=0x%08X\n", __func__, __LINE__, status);
 	/* stop CP */
@@ -2131,11 +2132,11 @@ int r100_asic_reset(struct radeon_device *rdev)
 		G_000E40_TAM_BUSY(status) || G_000E40_PB_BUSY(status)) {
 		dev_err(rdev->dev, "failed to reset GPU\n");
 		rdev->gpu_lockup = true;
-		return -1;
-	}
-	r100_mc_resume(rdev, &save);
+		ret = -1;
+	} else
 		dev_info(rdev->dev, "GPU reset succeed\n");
-	return 0;
+	r100_mc_resume(rdev, &save);
+	return ret;
 }
 
 void r100_set_common_regs(struct radeon_device *rdev)

drivers/gpu/drm/radeon/r300.c

@@ -405,12 +405,13 @@ int r300_asic_reset(struct radeon_device *rdev)
 {
 	struct r100_mc_save save;
 	u32 status, tmp;
+	int ret = 0;
 
-	r100_mc_stop(rdev, &save);
 	status = RREG32(R_000E40_RBBM_STATUS);
 	if (!G_000E40_GUI_ACTIVE(status)) {
 		return 0;
 	}
+	r100_mc_stop(rdev, &save);
 	status = RREG32(R_000E40_RBBM_STATUS);
 	dev_info(rdev->dev, "(%s:%d) RBBM_STATUS=0x%08X\n", __func__, __LINE__, status);
 	/* stop CP */
@@ -451,11 +452,11 @@ int r300_asic_reset(struct radeon_device *rdev)
 	if (G_000E40_GA_BUSY(status) || G_000E40_VAP_BUSY(status)) {
 		dev_err(rdev->dev, "failed to reset GPU\n");
 		rdev->gpu_lockup = true;
-		return -1;
-	}
-	r100_mc_resume(rdev, &save);
+		ret = -1;
+	} else
 		dev_info(rdev->dev, "GPU reset succeed\n");
-	return 0;
+	r100_mc_resume(rdev, &save);
+	return ret;
 }
 
 /*

drivers/gpu/drm/radeon/rs600.c

@@ -339,16 +339,16 @@ void rs600_bm_disable(struct radeon_device *rdev)
 
 int rs600_asic_reset(struct radeon_device *rdev)
 {
-	u32 status, tmp;
-
 	struct rv515_mc_save save;
+	u32 status, tmp;
+	int ret = 0;
 
-	/* Stops all mc clients */
-	rv515_mc_stop(rdev, &save);
 	status = RREG32(R_000E40_RBBM_STATUS);
 	if (!G_000E40_GUI_ACTIVE(status)) {
 		return 0;
 	}
+	/* Stops all mc clients */
+	rv515_mc_stop(rdev, &save);
 	status = RREG32(R_000E40_RBBM_STATUS);
 	dev_info(rdev->dev, "(%s:%d) RBBM_STATUS=0x%08X\n", __func__, __LINE__, status);
 	/* stop CP */
@@ -392,11 +392,11 @@ int rs600_asic_reset(struct radeon_device *rdev)
 	if (G_000E40_GA_BUSY(status) || G_000E40_VAP_BUSY(status)) {
 		dev_err(rdev->dev, "failed to reset GPU\n");
 		rdev->gpu_lockup = true;
-		return -1;
-	}
-	rv515_mc_resume(rdev, &save);
+		ret = -1;
+	} else
 		dev_info(rdev->dev, "GPU reset succeed\n");
-	return 0;
+	rv515_mc_resume(rdev, &save);
+	return ret;
 }
 
 /*