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Commit 23154377 authored by Sujeev Dias's avatar Sujeev Dias Committed by Gerrit - the friendly Code Review server
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mhi: core: for downlink transfer only assert wake if MHI is in lpm mode 



When MHI is in an active state, external device CPU cores can go
into a low power mode while device data movers processing data
transfer. Whenever host assert wake, it can cause device CPU to
exit low power mode even though there is no work to be done. For
downlink channels, assert wake only if MHI is in a low power mode
to avoid unnecessary wake ups.

CRs-Fixed: 2248650
Change-Id: I05ca7483a885237711a630844670e887572c13b7
Signed-off-by: default avatarSujeev Dias <sdias@codeaurora.org>
parent 8f90aea7

drivers/bus/mhi/core/mhi_main.c

+38 −26
Original line number Diff line number Diff line
@@ -276,6 +276,7 @@ int mhi_queue_skb(struct mhi_device *mhi_dev, 
	struct mhi_ring *buf_ring = &mhi_chan->buf_ring;

	struct mhi_buf_info *buf_info;

	struct mhi_tre *mhi_tre;

	bool assert_wake = false;



	if (mhi_is_ring_full(mhi_cntrl, tre_ring))

		return -ENOMEM;
@@ -294,7 +295,17 @@ int mhi_queue_skb(struct mhi_device *mhi_dev, 
		mhi_cntrl->runtime_get(mhi_cntrl, mhi_cntrl->priv_data);

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

	}



	/*

	 * For UL channels always assert WAKE until work is done,

	 * For DL channels only assert if MHI is in a LPM

	 */

	if (mhi_chan->dir == DMA_TO_DEVICE ||

	    (mhi_chan->dir == DMA_FROM_DEVICE &&

	     mhi_cntrl->pm_state != MHI_PM_M0)) {

		assert_wake = true;

		mhi_cntrl->wake_get(mhi_cntrl, false);

	}



	/* generate the tre */

	buf_info = buf_ring->wp;
@@ -328,17 +339,15 @@ int mhi_queue_skb(struct mhi_device *mhi_dev, 
		read_unlock_bh(&mhi_chan->lock);

	}



	if (mhi_chan->dir == DMA_FROM_DEVICE) {

		bool override = (mhi_cntrl->pm_state != MHI_PM_M0);



		mhi_cntrl->wake_put(mhi_cntrl, override);

	}

	if (mhi_chan->dir == DMA_FROM_DEVICE && assert_wake)

		mhi_cntrl->wake_put(mhi_cntrl, true);



	read_unlock_bh(&mhi_cntrl->pm_lock);



	return 0;



map_error:

	if (assert_wake)

		mhi_cntrl->wake_put(mhi_cntrl, false);

	read_unlock_bh(&mhi_cntrl->pm_lock);
@@ -402,13 +411,17 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, 
	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;

	struct mhi_ring *tre_ring;

	unsigned long flags;

	bool assert_wake = false;

	int ret;



	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);

	/*

	 * this check here only as a guard, it's always

	 * possible mhi can enter error while executing rest of function,

	 * which is not fatal so we do not need to hold pm_lock

	 */

	if (unlikely(MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))) {

		MHI_ERR("MHI is not in active state, pm_state:%s\n",

			to_mhi_pm_state_str(mhi_cntrl->pm_state));

		read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);



		return -EIO;

	}
@@ -419,18 +432,27 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, 
		mhi_cntrl->runtime_put(mhi_cntrl, mhi_cntrl->priv_data);

	}



	mhi_cntrl->wake_get(mhi_cntrl, false);

	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);



	tre_ring = &mhi_chan->tre_ring;

	if (mhi_is_ring_full(mhi_cntrl, tre_ring))

		goto error_queue;

		return -ENOMEM;



	ret = mhi_chan->gen_tre(mhi_cntrl, mhi_chan, buf, buf, len, mflags);

	if (unlikely(ret))

		goto error_queue;

		return ret;



	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);



	/*

	 * For UL channels always assert WAKE until work is done,

	 * For DL channels only assert if MHI is in a LPM

	 */

	if (mhi_chan->dir == DMA_TO_DEVICE ||

	    (mhi_chan->dir == DMA_FROM_DEVICE &&

	     mhi_cntrl->pm_state != MHI_PM_M0)) {

		assert_wake = true;

		mhi_cntrl->wake_get(mhi_cntrl, false);

	}



	if (likely(MHI_DB_ACCESS_VALID(mhi_cntrl->pm_state))) {

		unsigned long flags;
@@ -439,22 +461,12 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, 
		read_unlock_irqrestore(&mhi_chan->lock, flags);

	}



	if (mhi_chan->dir == DMA_FROM_DEVICE) {

		bool override = (mhi_cntrl->pm_state != MHI_PM_M0);



		mhi_cntrl->wake_put(mhi_cntrl, override);

	}

	if (mhi_chan->dir == DMA_FROM_DEVICE && assert_wake)

		mhi_cntrl->wake_put(mhi_cntrl, true);



	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);



	return 0;



error_queue:

	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);

	mhi_cntrl->wake_put(mhi_cntrl, false);

	read_unlock_irqrestore(&mhi_cntrl->pm_lock, flags);



	return -ENOMEM;

}



/* destroy specific device */