Often devices allocate DMA buffers before they do runtime pm resume. This is the case for example with v4l2 devices where buffers are allocated during 'VIDIOC_REQBUFS` and runtime resume happens later usually during 'VIDIOC_STREAMON'. In such cases the partial tlb flush when allocating will fail since the iommu is runtime suspended. This will print a warning and try to do full flush. But there is actually no need to flush the tlb before the consumer device is turned on. Fix the warning by skipping partial flush when allocating and instead do full flash in runtime resume. In order to do full flush from the resume cb, the test: if (pm_runtime_get_if_in_use(data->dev) <= 0) continue; needs to be removed from the flush all func since pm_runtime_get_if_in_use returns 0 while resuming and will skip the flush This patchset is a combination of 4 patches already sent in a different patchset: [1] and a warning fix from Sebastian Reichel [1] https://lore.kernel.org/linux-devicetree/20210923115840.17813-1-yong.wu@xxxxxxxxxxxx/ changes since v1: ----------------- * Added preparation patches to remove the unneeded 'for_each_m4u' usage and add a spinlock to protect access to tlb control registers. * remove the pm runtime status check as explained above. * refactor commit logs and inline doc * move the call to full flush to the bottom of the resume cb after all registers are updated. Sebastian Reichel (1): iommu/mediatek: Always check runtime PM status in tlb flush range callback Yong Wu (4): iommu/mediatek: Remove for_each_m4u in tlb_sync_all iommu/mediatek: Remove the power status checking in tlb flush all iommu/mediatek: Add tlb_lock in tlb_flush_all iommu/mediatek: Always tlb_flush_all when each PM resume drivers/iommu/mtk_iommu.c | 42 ++++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 20 deletions(-) -- 2.17.1
