linux-kernel - Re: [PATCH v4 9/9] bus: mhi: ep: wake up host if the MHI state is in M3

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Message-ID: <20230728153555.GA9129@thinkpad>
Date:   Fri, 28 Jul 2023 21:05:55 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Dan Carpenter <dan.carpenter@...aro.org>
Cc:     Krishna chaitanya chundru <quic_krichai@...cinc.com>,
        manivannan.sadhasivam@...aro.org, helgaas@...nel.org,
        linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_vbadigan@...cinc.com,
        quic_nitegupt@...cinc.com, quic_skananth@...cinc.com,
        quic_ramkri@...cinc.com, krzysztof.kozlowski@...aro.org,
        Jeffrey Hugo <quic_jhugo@...cinc.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Carpenter <error27@...il.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "open list:MHI BUS" <mhi@...ts.linux.dev>
Subject: Re: [PATCH v4 9/9] bus: mhi: ep: wake up host if the MHI state is in
 M3

On Fri, Jul 28, 2023 at 08:50:55AM +0300, Dan Carpenter wrote:
> On Fri, Jul 28, 2023 at 10:04:52AM +0530, Manivannan Sadhasivam wrote:
> > > @@ -464,6 +484,13 @@ 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) {
> > > +		if (mhi_ep_wake_host(mhi_cntrl)) {
> > 
> > Don't you need lock here in the case of multiple queue requests?
> > 
> > - Mani
> > 
> > > +			dev_err(dev, "Failed to wakeup host\n");
> > > +			return -ENODEV;
> > > +		}
> > > +	}
> > > +
> > >  	mutex_lock(&mhi_chan->lock);
>         ^^^^^^^^^^^^^^^^^^^^^^^^^^
> This lock isn't enough?
> 

The position of this lock won't prevent cocurrent access to mhi_ep_wake_host().

- Mani

> regards,
> dan carpenter

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