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

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Message-ID: <616fe76b6757e8d545cfaaba1ab3ab50@codeaurora.org>
Date:   Mon, 16 Nov 2020 09:36:09 -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

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.

> 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