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Commit dc64b4e1 authored by Sujeev Dias's avatar Sujeev Dias
Browse files

mhi: core: add support to pause or resume data transfer 



Some MHI clients needs support to suspend transfers during
device suspend. Adding support to pause or resume pending transfers
without needing to reset the channel state.

CRs-Fixed: 2492779
Change-Id: I961d27d29331f07bf3a08b80ec1133f3b9a59e81
Signed-off-by: default avatarSujeev Dias <sdias@codeaurora.org>
parent 25bd7a1b

drivers/bus/mhi/core/mhi_internal.h

+1 −0
Original line number Diff line number Diff line
@@ -350,6 +350,7 @@ enum mhi_cmd_type { 
enum MHI_CMD {

	MHI_CMD_RESET_CHAN,

	MHI_CMD_START_CHAN,

	MHI_CMD_STOP_CHAN,

	MHI_CMD_TIMSYNC_CFG,

};

drivers/bus/mhi/core/mhi_main.c

+119 −0
Original line number Diff line number Diff line
@@ -1578,6 +1578,11 @@ int mhi_send_cmd(struct mhi_controller *mhi_cntrl, 
		cmd_tre->dword[0] = MHI_TRE_CMD_START_DWORD0;

		cmd_tre->dword[1] = MHI_TRE_CMD_START_DWORD1(chan);

		break;

	case MHI_CMD_STOP_CHAN:

		cmd_tre->ptr = MHI_TRE_CMD_STOP_PTR;

		cmd_tre->dword[0] = MHI_TRE_CMD_STOP_DWORD0;

		cmd_tre->dword[1] = MHI_TRE_CMD_STOP_DWORD1(chan);

		break;

	case MHI_CMD_TIMSYNC_CFG:

		cmd_tre->ptr = MHI_TRE_CMD_TSYNC_CFG_PTR;

		cmd_tre->dword[0] = MHI_TRE_CMD_TSYNC_CFG_DWORD0;
@@ -2031,6 +2036,120 @@ void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev) 
}

EXPORT_SYMBOL(mhi_unprepare_from_transfer);



static int mhi_update_channel_state(struct mhi_controller *mhi_cntrl,

				    struct mhi_chan *mhi_chan,

				    enum MHI_CMD cmd)

{

	int ret = -EIO;



	mutex_lock(&mhi_chan->mutex);



	MHI_VERB("Changing chan:%d to state:%s\n",

		 mhi_chan->chan, cmd == MHI_CMD_START_CHAN ? "START" : "STOP");



	/* if channel is not active state state do not allow to state change */

	if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED) {

		ret = -EINVAL;

		MHI_LOG("channel:%d is not in active state, ch_state%d\n",

			mhi_chan->chan, mhi_chan->ch_state);

		goto error_chan_state;

	}



	read_lock_bh(&mhi_cntrl->pm_lock);

	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {

		MHI_ERR("MHI host is not in active state\n");

		read_unlock_bh(&mhi_cntrl->pm_lock);

		ret = -EIO;

		goto error_chan_state;

	}



	mhi_cntrl->wake_toggle(mhi_cntrl);

	read_unlock_bh(&mhi_cntrl->pm_lock);

	mhi_cntrl->runtime_get(mhi_cntrl, mhi_cntrl->priv_data);

	mhi_cntrl->runtime_put(mhi_cntrl, mhi_cntrl->priv_data);



	ret = mhi_send_cmd(mhi_cntrl, mhi_chan, cmd);

	if (ret) {

		MHI_ERR("Failed to send start chan cmd\n");

		goto error_chan_state;

	}



	ret = wait_for_completion_timeout(&mhi_chan->completion,

				msecs_to_jiffies(mhi_cntrl->timeout_ms));

	if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {

		MHI_ERR("Failed to receive cmd completion for chan:%d\n",

			mhi_chan->chan);

		ret = -EIO;

		goto error_chan_state;

	}



	ret = 0;



	MHI_VERB("chan:%d successfully transition to state:%s\n",

		 mhi_chan->chan, cmd == MHI_CMD_START_CHAN ? "START" : "STOP");



error_chan_state:

	mutex_unlock(&mhi_chan->mutex);



	return ret;

}



int mhi_pause_transfer(struct mhi_device *mhi_dev)

{

	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

	struct mhi_chan *mhi_chan;

	int dir, ret;



	for (dir = 0; dir < 2; dir++) {

		mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;



		if (!mhi_chan)

			continue;



		/*

		 * If one channel successful stopped but second channel fail

		 * to stop, we still bail out because there is no way to

		 * recover it. Resuming the stopped channel won't be helpful

		 * and likely to fail.

		 */

		ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,

					       MHI_CMD_STOP_CHAN);

		if (ret)

			return ret;

	}



	return 0;

}

EXPORT_SYMBOL(mhi_pause_transfer);



int mhi_resume_transfer(struct mhi_device *mhi_dev)

{

	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

	struct mhi_chan *mhi_chan;

	int dir, ret;



	for (dir = 0; dir < 2; dir++) {

		mhi_chan = dir ? mhi_dev->ul_chan : mhi_dev->dl_chan;



		if (!mhi_chan)

			continue;



		/*

		 * Similar to pause, if one channel start, and other channel

		 * failed to start, we would bail out. No need to pause

		 * the start channel. Client will be resetting both

		 * channels upon failure.

		 */

		ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,

					       MHI_CMD_START_CHAN);

		if (ret)

			return ret;

	}



	return 0;

}

EXPORT_SYMBOL(mhi_resume_transfer);



int mhi_get_no_free_descriptors(struct mhi_device *mhi_dev,

				enum dma_data_direction dir)

{

include/linux/mhi.h

+16 −0
Original line number Diff line number Diff line
@@ -534,6 +534,22 @@ int mhi_prepare_for_transfer(struct mhi_device *mhi_dev); 
 */

void mhi_unprepare_from_transfer(struct mhi_device *mhi_dev);



/**

 * mhi_pause_transfer - Pause the current transfe

 * Moves both UL and DL channels to STOP state to halt

 * pending transfers.

 * @mhi_dev: Device associated with the channels

 */

int mhi_pause_transfer(struct mhi_device *mhi_dev);



/**

 * mhi_resume_transfer - resume current transfer

 * Moves both UL and DL channels to START state to

 * resume transfer.

 * @mhi_dev: Device associated with the channels

 */

int mhi_resume_transfer(struct mhi_device *mhi_dev);



/**

 * mhi_get_no_free_descriptors - Get transfer ring length

 * Get # of TD available to queue buffers