linux-kernel - Re: [PATCH v2 1/6] bus: mhi: core: Allow receiving a STOP channel command response

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Date:   Sat, 21 Nov 2020 22:46:01 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Bhaumik Bhatt <bbhatt@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
        jhugo@...eaurora.org, loic.poulain@...aro.org,
        kvalo@...eaurora.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/6] bus: mhi: core: Allow receiving a STOP channel
 command response

On Mon, Nov 16, 2020 at 09:36:09AM -0800, Bhaumik Bhatt wrote:
> Hi Mani,
> 
> On 2020-11-15 23:13, Manivannan Sadhasivam wrote:
> > On Wed, Nov 11, 2020 at 11:21:08AM -0800, Bhaumik Bhatt wrote:
> > > Add support to receive the response to a STOP channel command to the
> > > MHI bus. If a client would like to STOP a channel instead of issuing
> > > a RESET to it, this would provide support for it.
> > > 
> > > Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
> > > ---
> > >  drivers/bus/mhi/core/init.c | 5 +++--
> > >  drivers/bus/mhi/core/main.c | 5 +++++
> > >  2 files changed, 8 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> > > index 8cefa35..4d34d62 100644
> > > --- a/drivers/bus/mhi/core/init.c
> > > +++ b/drivers/bus/mhi/core/init.c
> > > @@ -1267,8 +1267,9 @@ static int mhi_driver_remove(struct device *dev)
> > > 
> > >  		mutex_lock(&mhi_chan->mutex);
> > > 
> > > -		if (ch_state[dir] == MHI_CH_STATE_ENABLED &&
> > > -		    !mhi_chan->offload_ch)
> > > +		if ((ch_state[dir] == MHI_CH_STATE_ENABLED ||
> > > +		     ch_state[dir] == MHI_CH_STATE_STOP) &&
> > 
> > This enum is not defined in this patch so it'll break. Please add a
> > separate
> > patch which introduces the new state enums alone and then have patches
> > 1/2
> > as a followup.
> > 
> It is actually already defined and present in internal.h as enum
> mhi_ch_state.
> 
> The old set of enums has MHI_CH_STATE_STOP from enum mhi_ch_state and the
> new
> enum I introduced is MHI_CH_STATE_TYPE_STOP from enum enum
> mhi_ch_state_type.
> 
> If it seems confusing, suggestions to renaming them are welcome.
> 

Ah, sorry. I got confused with MHI_CH_STATE_TYPE_STOP and MHI_CH_STATE_STOP.
Ignore my previous comment.

Thanks,
Mani

> > Also this change is not belonging to this commit I believe.
> > 
> I included this change here because, a channel can be in "stopped" state and
> a user module could be unloaded or a crash could force a driver remove
> leading
> us to come this check.
> 
> If you think I should move it as a separate patch, let me know.
> > Thanks,
> > Mani
> > 
> > > +		     !mhi_chan->offload_ch)
> > >  			mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
> > > 
> > >  		mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
> > > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> > > index f953e2a..ad881a1 100644
> > > --- a/drivers/bus/mhi/core/main.c
> > > +++ b/drivers/bus/mhi/core/main.c
> > > @@ -1194,6 +1194,11 @@ int mhi_send_cmd(struct mhi_controller
> > > *mhi_cntrl,
> > >  		cmd_tre->dword[0] = MHI_TRE_CMD_RESET_DWORD0;
> > >  		cmd_tre->dword[1] = MHI_TRE_CMD_RESET_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_START_CHAN:
> > >  		cmd_tre->ptr = MHI_TRE_CMD_START_PTR;
> > >  		cmd_tre->dword[0] = MHI_TRE_CMD_START_DWORD0;
> > > --
> > > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
> > > Forum,
> > > a Linux Foundation Collaborative Project
> > > 
> 
> Thanks,
> Bhaumik
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project