On Tue, Apr 06, 2021 at 11:11:54AM +0200, Loic Poulain wrote:
> 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@xxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Thanks,
Mani
> ---
> v2: mhi_reset_data_chan: move put under existing DMA_TO_DEVICE if block
>
> drivers/bus/mhi/core/main.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index c780234..6e72239 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -584,8 +584,11 @@ 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,
> @@ -1021,9 +1024,11 @@ 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);
> @@ -1034,6 +1039,9 @@ static int mhi_queue(struct mhi_device *mhi_dev, struct mhi_buf_info *buf_info,
> if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl)))
> 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);
>
> @@ -1416,8 +1424,11 @@ 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);
> --
> 2.7.4
>
