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

[Manivannan Sadhasivam <mani@kernel.org>]

On Fri, Jun 30, 2023 at 04:22:11PM +0530, Krishna chaitanya chundru wrote:
> 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.
> 

Endpoint cannot bring the host to D0, it can only wake up the host and the host
will bring the device to D0.

> Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
> ---
>  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);

This is not needed.

> +		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);
> +

Move this change to a function like mhi_ep_wake_host().

- Mani

>  	mutex_lock(&mhi_chan->lock);
>  
>  	do {
> -- 
> 2.7.4
> 

-- 
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