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

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Date:   Mon, 23 Nov 2020 16:23:44 -0800
From:   Bhaumik Bhatt <bbhatt@...eaurora.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.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 2020-11-21 09:16 AM, Manivannan Sadhasivam wrote:
> 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
> 
No problem.
>> > 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

Thanks,
Bhaumik
---
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
Forum,
a Linux Foundation Collaborative Project