linux-kernel - Re: [PATCH v1 3/7] bus: mhi: core: Handle EDL mode entry appropriately

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Date:   Wed, 31 Mar 2021 16:29:43 +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, linux-kernel@...r.kernel.org,
        carl.yin@...ctel.com, naveen.kumar@...ctel.com,
        loic.poulain@...aro.org, abickett@...eaurora.org
Subject: Re: [PATCH v1 3/7] bus: mhi: core: Handle EDL mode entry
 appropriately

On Mon, Mar 29, 2021 at 06:28:20PM -0700, Bhaumik Bhatt wrote:
> Device entering EDL or Emergency Download Mode will be in a
> SYS_ERROR MHI state. This requires MHI host to proceed with the
> EDL image download over BHI before device can enter an MHI READY
> state and proceed with further bootup. Allow this to be handled
> by relying on the execution environment check after SYS_ERROR
> processing to determine whether to wait for an MHI READY or
> download the EDL image over BHI after moving MHI PM state to
> Power on Reset internally. This way handling is contained well
> within the MHI core driver and helps pave the way for Flash
> Programmer execution environment functionality.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Thanks,
Mani

> ---
>  drivers/bus/mhi/core/pm.c | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index fbe9447..b65222e 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -564,6 +564,7 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
>  static void mhi_pm_sys_error_transition(struct mhi_controller *mhi_cntrl)
>  {
>  	enum mhi_pm_state cur_state, prev_state;
> +	enum dev_st_transition next_state;
>  	struct mhi_event *mhi_event;
>  	struct mhi_cmd_ctxt *cmd_ctxt;
>  	struct mhi_cmd *mhi_cmd;
> @@ -677,7 +678,23 @@ static void mhi_pm_sys_error_transition(struct mhi_controller *mhi_cntrl)
>  		er_ctxt->wp = er_ctxt->rbase;
>  	}
>  
> -	mhi_ready_state_transition(mhi_cntrl);
> +	/* Transition to next state */
> +	if (MHI_IN_PBL(mhi_get_exec_env(mhi_cntrl))) {
> +		write_lock_irq(&mhi_cntrl->pm_lock);
> +		cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_POR);
> +		write_unlock_irq(&mhi_cntrl->pm_lock);
> +		if (cur_state != MHI_PM_POR) {
> +			dev_err(dev, "Error moving to state %s from %s\n",
> +				to_mhi_pm_state_str(MHI_PM_POR),
> +				to_mhi_pm_state_str(cur_state));
> +			goto exit_sys_error_transition;
> +		}
> +		next_state = DEV_ST_TRANSITION_PBL;
> +	} else {
> +		next_state = DEV_ST_TRANSITION_READY;
> +	}
> +
> +	mhi_queue_state_transition(mhi_cntrl, next_state);
>  
>  exit_sys_error_transition:
>  	dev_dbg(dev, "Exiting with PM state: %s, MHI state: %s\n",
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>