bus: mhi: core: Fix MHI runtime_pm behavior

commit 4547a749be997eb12ea7edcf361ec2a5329f7aec upstream.

This change ensures that PM reference is always get during packet
queueing and released either after queuing completion (RX) or once
the buffer has been consumed (TX). This guarantees proper update for
underlying MHI controller runtime status (e.g. last_busy timestamp)
and prevents suspend to be triggered while TX packets are flying,
or before we completed update of the RX ring.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617700315-12492-1-git-send-email-loic.poulain@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 3bfee5bca9e7d9bb6f8b9dce946f3b70fa318195..1068234e6c7e848c8989e202c8de1440e2d13f11 100644 (file)
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -589,8 +589,11 @@ static int parse_xfer_event(struct mhi_controller *mhi_cntrl,
                        /* notify client */
                        mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
 
-                       if (mhi_chan->dir == DMA_TO_DEVICE)
+                       if (mhi_chan->dir == DMA_TO_DEVICE) {
                                atomic_dec(&mhi_cntrl->pending_pkts);
+                               /* Release the reference got from mhi_queue() */
+                               mhi_cntrl->runtime_put(mhi_cntrl);
+                       }
 
                        /*
                         * Recycle the buffer if buffer is pre-allocated,
@@ -1062,9 +1065,11 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
        if (unlikely(ret))
                goto exit_unlock;
 
-       /* trigger M3 exit if necessary */
-       if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state))
-               mhi_trigger_resume(mhi_cntrl);
+       /* Packet is queued, take a usage ref to exit M3 if necessary
+        * for host->device buffer, balanced put is done on buffer completion
+        * for device->host buffer, balanced put is after ringing the DB
+        */
+       mhi_cntrl->runtime_get(mhi_cntrl);
 
        /* Assert dev_wake (to exit/prevent M1/M2)*/
        mhi_cntrl->wake_toggle(mhi_cntrl);
@@ -1079,6 +1084,9 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
 
        mhi_ring_chan_db(mhi_cntrl, mhi_chan);
 
+       if (dir == DMA_FROM_DEVICE)
+               mhi_cntrl->runtime_put(mhi_cntrl);
+
 exit_unlock:
        read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);
 
@@ -1470,8 +1478,11 @@ static void mhi_reset_data_chan(struct mhi_controller *mhi_cntrl,
        while (tre_ring->rp != tre_ring->wp) {
                struct mhi_buf_info *buf_info = buf_ring->rp;
 
-               if (mhi_chan->dir == DMA_TO_DEVICE)
+               if (mhi_chan->dir == DMA_TO_DEVICE) {
                        atomic_dec(&mhi_cntrl->pending_pkts);
+                       /* Release the reference got from mhi_queue() */
+                       mhi_cntrl->runtime_put(mhi_cntrl);
+               }
 
                if (!buf_info->pre_mapped)
                        mhi_cntrl->unmap_single(mhi_cntrl, buf_info);