[PATCH v2 8/8] bus: mhi: ep: wake up host is the MHI state is in M3

[Krishna chaitanya chundru]

If the MHI state is in M3 then the most probably the host kept the
device in D3 hot or D3 cold, due to that endpoint transctions will not
be read by the host, so endpoint needs to bring the host to D0 which
eventually bring back the MHI state to M0.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
 drivers/bus/mhi/ep/main.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index 6008818..42d3791 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -451,12 +451,14 @@ int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
 	struct mhi_ep_cntrl *mhi_cntrl = mhi_dev->mhi_cntrl;
 	struct mhi_ep_chan *mhi_chan = mhi_dev->dl_chan;
 	struct device *dev = &mhi_chan->mhi_dev->dev;
+	u32 buf_left, read_offset, count = 0;
 	struct mhi_ring_element *el;
-	u32 buf_left, read_offset;
 	struct mhi_ep_ring *ring;
 	enum mhi_ev_ccs code;
+	enum mhi_state state;
 	void *read_addr;
 	u64 write_addr;
+	bool mhi_reset;
 	size_t tr_len;
 	u32 tre_len;
 	int ret;
@@ -464,6 +466,18 @@ int mhi_ep_queue_skb(struct mhi_ep_device *mhi_dev, struct sk_buff *skb)
 	buf_left = skb->len;
 	ring = &mhi_cntrl->mhi_chan[mhi_chan->chan].ring;
 
+	if (mhi_cntrl->mhi_state == MHI_STATE_M3) {
+		dev_dbg(dev, "wake up by ch id %x\n", mhi_chan->chan);
+		mhi_cntrl->wakeup_host(mhi_cntrl);
+	}
+
+	/* Wait for Host to set the M0 state */
+	do {
+		msleep(M0_WAIT_DELAY_MS);
+		mhi_ep_mmio_get_mhi_state(mhi_cntrl, &state, &mhi_reset);
+		count++;
+	} while (state != MHI_STATE_M0 && count < M0_WAIT_COUNT);
+
 	mutex_lock(&mhi_chan->lock);
 
 	do {
-- 
2.7.4