linux-kernel - Re: [PATCH v1 6/7] bus: mhi: core: Wait for MHI READY state in most scenarios

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Date:   Wed, 31 Mar 2021 16:43:31 +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 6/7] bus: mhi: core: Wait for MHI READY state in most
 scenarios

On Mon, Mar 29, 2021 at 06:28:23PM -0700, Bhaumik Bhatt wrote:
> When moving from SYS_ERROR transition to a different execution
> environment, MHI host relies on the BHI register read to spawn
> the next image download or wait for READY -> M0 states. The
> device can at times move the execution environment to mission
> mode when a pass through is expected, which can result in a
> stall. Initiate a wait for MHI READY and write M0 such that the
> device can proceed with state change event updates for any new
> execution environment being entered. This allows us to remove
> conditionals in handling firmware load for PBL modes and keeps
> the execution environment out of the picture as it can change at
> any time.
> 
> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>

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

Thanks,
Mani

> ---
>  drivers/bus/mhi/core/boot.c | 4 ++--
>  drivers/bus/mhi/core/pm.c   | 3 +--
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/boot.c b/drivers/bus/mhi/core/boot.c
> index 0f0ae88..8100cf5 100644
> --- a/drivers/bus/mhi/core/boot.c
> +++ b/drivers/bus/mhi/core/boot.c
> @@ -416,8 +416,8 @@ void mhi_fw_load_handler(struct mhi_controller *mhi_cntrl)
>  		}
>  	}
>  
> -	/* If device is in pass through, do reset to ready state transition */
> -	if (mhi_cntrl->ee == MHI_EE_PTHRU)
> +	/* wait for ready on pass through or any other execution environment */
> +	if (mhi_cntrl->ee != MHI_EE_EDL && mhi_cntrl->ee != MHI_EE_PBL)
>  		goto fw_load_ready_state;
>  
>  	fw_name = (mhi_cntrl->ee == MHI_EE_EDL) ?
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index 7ac9dfe..b6920a5 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -763,8 +763,7 @@ void mhi_pm_st_worker(struct work_struct *work)
>  			if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state))
>  				mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
>  			write_unlock_irq(&mhi_cntrl->pm_lock);
> -			if (MHI_IN_PBL(mhi_cntrl->ee))
> -				mhi_fw_load_handler(mhi_cntrl);
> +			mhi_fw_load_handler(mhi_cntrl);
>  			break;
>  		case DEV_ST_TRANSITION_SBL:
>  			write_lock_irq(&mhi_cntrl->pm_lock);
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>