linux-kernel - Re: [PATCH v2 2/6] bus: mhi: core: Improvements to the channel handling state machine

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Message-ID: <20201116102220.GJ3926@Mani-XPS-13-9360>
Date:   Mon, 16 Nov 2020 15:52:20 +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 2/6] bus: mhi: core: Improvements to the channel
 handling state machine

On Wed, Nov 11, 2020 at 11:21:09AM -0800, Bhaumik Bhatt wrote:
> Add support to enable sending the stop channel command and
> improve the channel handling state machine such that all commands
> go through a common function. This can help ensure that the state
> machine is not violated in any way and adheres to the MHI
> specification.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
> ---
>  drivers/bus/mhi/core/init.c     |   6 ++
>  drivers/bus/mhi/core/internal.h |  12 +++
>  drivers/bus/mhi/core/main.c     | 163 ++++++++++++++++++++++++----------------
>  3 files changed, 116 insertions(+), 65 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index 4d34d62..c9b1de8 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -51,6 +51,12 @@ const char * const mhi_state_str[MHI_STATE_MAX] = {
>  	[MHI_STATE_SYS_ERR] = "SYS_ERR",
>  };
>  
> +const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX] = {
> +	[MHI_CH_STATE_TYPE_RESET] = "RESET",
> +	[MHI_CH_STATE_TYPE_STOP] = "STOP",
> +	[MHI_CH_STATE_TYPE_START] = "START",
> +};
> +
>  static const char * const mhi_pm_state_str[] = {
>  	[MHI_PM_STATE_DISABLE] = "DISABLE",
>  	[MHI_PM_STATE_POR] = "POR",
> diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
> index 2df8de5..f4efb15 100644
> --- a/drivers/bus/mhi/core/internal.h
> +++ b/drivers/bus/mhi/core/internal.h
> @@ -369,6 +369,18 @@ enum mhi_ch_state {
>  	MHI_CH_STATE_ERROR = 0x5,
>  };
>  
> +enum mhi_ch_state_type {
> +	MHI_CH_STATE_TYPE_RESET,
> +	MHI_CH_STATE_TYPE_STOP,
> +	MHI_CH_STATE_TYPE_START,
> +	MHI_CH_STATE_TYPE_MAX,
> +};
> +

As said in previous patch, this needs to be moved to a separate one.

> +extern const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX];
> +#define TO_CH_STATE_TYPE_STR(state) (((state) >= MHI_CH_STATE_TYPE_MAX) ? \
> +				     "INVALID_STATE" : \
> +				     mhi_ch_state_type_str[state])
> +
>  #define MHI_INVALID_BRSTMODE(mode) (mode != MHI_DB_BRST_DISABLE && \
>  				    mode != MHI_DB_BRST_ENABLE)
>  
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index ad881a1..1226933 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -1220,56 +1220,120 @@ int mhi_send_cmd(struct mhi_controller *mhi_cntrl,
>  	return 0;
>  }
>  

[...]

> +static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
> +				    struct mhi_chan *mhi_chan)
> +{
> +	int ret;
> +	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> +
> +	dev_dbg(dev, "Entered: unprepare channel:%d\n", mhi_chan->chan);

Please get rid of these debug prints. We have some of them right now but they
should be removed at some point. For debugging, use ftrace.

Thanks,
Mani