iommu/mediatek: Always check runtime PM status in tlb flush range callback

In case of v4l2_reqbufs() it is possible, that a TLB flush is done
without runtime PM being enabled. In that case the "Partial TLB flush
timed out, falling back to full flush" warning is printed.

Commit c0b57581b7 ("iommu/mediatek: Add power-domain operation")
introduced has_pm as optimization to avoid checking runtime PM
when there is no power domain attached. But without the PM domain
there is still the device driver's runtime PM suspend handler, which
disables the clock. Thus flushing should also be avoided when there
is no PM domain involved.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Yong Wu <yong.wu@mediatek.com>
Link: https://lore.kernel.org/r/20211208120744.2415-3-dafna.hirschfeld@collabora.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/mtk_iommu.c

@@ -225,16 +225,13 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
 					   size_t granule,
 					   struct mtk_iommu_data *data)
 {
-	bool has_pm = !!data->dev->pm_domain;
 	unsigned long flags;
 	int ret;
 	u32 tmp;
 
 	for_each_m4u(data) {
-		if (has_pm) {
-			if (pm_runtime_get_if_in_use(data->dev) <= 0)
-				continue;
-		}
+		if (pm_runtime_get_if_in_use(data->dev) <= 0)
+			continue;
 
 		spin_lock_irqsave(&data->tlb_lock, flags);
 		writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
@@ -259,8 +256,7 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
 		writel_relaxed(0, data->base + REG_MMU_CPE_DONE);
 		spin_unlock_irqrestore(&data->tlb_lock, flags);
 
-		if (has_pm)
-			pm_runtime_put(data->dev);
+		pm_runtime_put(data->dev);
 	}
 }