drm/panfrost: Improve error reporting in panfrost_gpu_power_on

It is useful to know which component cannot be powered on.

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200207052627.130118-4-drinkcat@chromium.org

drivers/gpu/drm/panfrost/panfrost_gpu.c

@@ -308,17 +308,20 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev)
 	gpu_write(pfdev, L2_PWRON_LO, pfdev->features.l2_present);
 	ret = readl_relaxed_poll_timeout(pfdev->iomem + L2_READY_LO,
 		val, val == pfdev->features.l2_present, 100, 1000);
+	if (ret)
+		dev_err(pfdev->dev, "error powering up gpu L2");
 
 	gpu_write(pfdev, SHADER_PWRON_LO, pfdev->features.shader_present);
-	ret |= readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO,
+	ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_READY_LO,
 		val, val == pfdev->features.shader_present, 100, 1000);
+	if (ret)
+		dev_err(pfdev->dev, "error powering up gpu shader");
 
 	gpu_write(pfdev, TILER_PWRON_LO, pfdev->features.tiler_present);
-	ret |= readl_relaxed_poll_timeout(pfdev->iomem + TILER_READY_LO,
+	ret = readl_relaxed_poll_timeout(pfdev->iomem + TILER_READY_LO,
 		val, val == pfdev->features.tiler_present, 100, 1000);
-
 	if (ret)
-		dev_err(pfdev->dev, "error powering up gpu");
+		dev_err(pfdev->dev, "error powering up gpu tiler");
 }
 
 void panfrost_gpu_power_off(struct panfrost_device *pfdev)