On Sat, Jul 11, 2020 at 2:51 PM Yong Wu [off-list ref] wrote:

In the previous SoC, the M4U HW is in the EMI power domain which is
always on. the latest M4U is in the display power domain which may be
turned on/off, thus we have to add pm_runtime interface for it.

we should enable its power before M4U hw initial. and disable it after HW
initialize.

When the engine work, the engine always enable the power and clocks for
smi-larb/smi-common, then the M4U's power will always be powered on
automatically via the device link with smi-common.

Note: we don't enable the M4U power in iommu_map/unmap for tlb flush.
If its power already is on, of course it is ok. if the power is off,
the main tlb will be reset while M4U power on, thus the tlb flush while
m4u power off is unnecessary, just skip it.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
 drivers/iommu/mtk_iommu.c | 54 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 47 insertions(+), 7 deletions(-)
...
        for_each_m4u(data) {
+               /* skip tlb flush when pm is not active */
+               if (pm_runtime_enabled(data->dev) &&
+                   !pm_runtime_active(data->dev))
+                       continue;
+

pm_runtime_active(dev) == false implies dev->power.disable_depth == 0,
which implies pm_runtime_enabled(dev) == true, so the
pm_runtime_enabled(data->dev) can be omitted here.

                spin_lock_irqsave(&data->tlb_lock, flags);
                writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
                               data->base + data->plat_data->inv_sel_reg);
...

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel