linux-kernel - Re: [PATCH] bus: mhi: host: Skip MHI reset if device is in RDDM

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Date:   Wed, 10 May 2023 08:50:43 -0600
From:   Jeffrey Hugo <quic_jhugo@...cinc.com>
To:     Qiang Yu <quic_qianyu@...cinc.com>, <mani@...nel.org>
CC:     <mhi@...ts.linux.dev>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_cang@...cinc.com>,
        <quic_mrana@...cinc.com>
Subject: Re: [PATCH] bus: mhi: host: Skip MHI reset if device is in RDDM

On 5/10/2023 12:04 AM, Qiang Yu wrote:
> In RDDM EE, device can not process MHI reset
> issued by host. In case of MHI power off, host
> is issuing MHI reset and polls for it to get
> cleared until it times out. Since this timeout
> can not be avoided in case of RDDM, skip the
> MHI reset in this scenarios.

Looks like you only use ~45 columns of 75 possible.  Feels a little odd. 
  Any particular reason for that?

Fixes tag?

> Signed-off-by: Qiang Yu <quic_qianyu@...cinc.com>
> ---
>   drivers/bus/mhi/host/pm.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
> index 0834590..8a4362d 100644
> --- a/drivers/bus/mhi/host/pm.c
> +++ b/drivers/bus/mhi/host/pm.c
> @@ -470,6 +470,10 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
>   
>   	/* Trigger MHI RESET so that the device will not access host memory */
>   	if (!MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
> +		/* Skip MHI RESET if in RDDM state */
> +		if (mhi_cntrl->rddm_image && mhi_get_exec_env(mhi_cntrl) == MHI_EE_RDDM)
> +			goto skip_mhi_reset;
> +
>   		dev_dbg(dev, "Triggering MHI Reset in device\n");
>   		mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
>   
> @@ -495,6 +499,7 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
>   		}
>   	}
>   
> +skip_mhi_reset:
>   	dev_dbg(dev,
>   		 "Waiting for all pending event ring processing to complete\n");
>   	mhi_event = mhi_cntrl->mhi_event;