linux-kernel - Re: [PATCH 5/5] bus: host: mhi: Need to honor sys_err at power

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Message-ID: <21bb1db4-f84b-4d15-876a-cf2635f7fada@quicinc.com>
Date: Wed, 9 Jul 2025 18:20:41 +0530
From: Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To: <Vivek.Pernamitta@...cinc.com>, Manivannan Sadhasivam <mani@...nel.org>
CC: <mhi@...ts.linux.dev>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Vivek Pernamitta <quic_vpernami@...cinc.com>
Subject: Re: [PATCH 5/5] bus: host: mhi: Need to honor sys_err at power_up
 state



On 7/3/2025 8:39 PM, Vivek.Pernamitta@...cinc.com wrote:
> From: Vivek Pernamitta <quic_vpernami@...cinc.com>
> 
> In mhi_sync_power_up() host waits for device to enter in to mission mode
> but SYS_ERR is an valid state, If device sends an SYS_ERR host will bail
> out for wait_event_timeout() as MHI is in error state and calls
> mhi_power_down which will teardown MHI driver probe.
Add "if MHI is tear downed sys err can't be serviced and mhi can't
be recovered".
> 
> If there is any SYS_ERR, sys_err handler needs to process SYS_ERR state
> and queues the next state transition for device to bring in to Mission
> mode, so mhi_sync_power_up() will wait for device to enter in to
s/will wait for/needs to wait for
> mission mode.
> 
> Signed-off-by: Vivek Pernamitta <quic_vpernami@...cinc.com>
> ---
>   drivers/bus/mhi/host/internal.h | 2 ++
>   drivers/bus/mhi/host/pm.c       | 2 +-
>   2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/host/internal.h b/drivers/bus/mhi/host/internal.h
> index 1054e67bb450d2634771d092ed42bbdd63380472..00e46176654d8dc2f28b1535d9ef68233266ff3b 100644
> --- a/drivers/bus/mhi/host/internal.h
> +++ b/drivers/bus/mhi/host/internal.h
> @@ -170,6 +170,8 @@ enum mhi_pm_state {
>   							MHI_PM_IN_ERROR_STATE(pm_state))
>   #define MHI_PM_IN_SUSPEND_STATE(pm_state)		(pm_state & \
>   							(MHI_PM_M3_ENTER | MHI_PM_M3))
> +#define MHI_PM_IN_BAD_STATE(pm_state)			((pm_state == MHI_PM_FW_DL_ERR) || \
> +							(pm_state >= MHI_PM_SYS_ERR_FAIL))
MHI_PM_IN_UNRECOVERABLE_ERROR ?

- Krishna Chaitanya.
>   
>   #define NR_OF_CMD_RINGS					1
>   #define CMD_EL_PER_RING					128
> diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
> index 2af34980e14250cada75c981b690bc9581715212..ee50efc57cf713a7cf38a670cb49ab09a83b30ee 100644
> --- a/drivers/bus/mhi/host/pm.c
> +++ b/drivers/bus/mhi/host/pm.c
> @@ -1280,7 +1280,7 @@ int mhi_sync_power_up(struct mhi_controller *mhi_cntrl)
>   		mhi_cntrl->ready_timeout_ms : mhi_cntrl->timeout_ms;
>   	wait_event_timeout(mhi_cntrl->state_event,
>   			   MHI_IN_MISSION_MODE(mhi_cntrl->ee) ||
> -			   MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state),
> +			   MHI_PM_IN_BAD_STATE(mhi_cntrl->pm_state),
>   			   msecs_to_jiffies(timeout_ms));
>   
>   	ret = (MHI_IN_MISSION_MODE(mhi_cntrl->ee)) ? 0 : -ETIMEDOUT;
>