linux-kernel - Re: [PATCH 3/3] bus: mhi: keep device context through suspend cycles

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Message-ID: <b72b3635-1c09-444f-98f5-30fcc219b297@oss.qualcomm.com>
Date: Tue, 8 Jul 2025 15:45:39 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Jeff Johnson <jjohnson@...nel.org>,
        Jeff Hugo <jeff.hugo@....qualcomm.com>,
        Youssef Samir <quic_yabdulra@...cinc.com>,
        Matthew Leung <quic_mattleun@...cinc.com>, Yan Zhen <yanzhen@...o.com>,
        Alexander Wilhelm <alexander.wilhelm@...termo.com>,
        Alex Elder <elder@...nel.org>, Kunwu Chan <chentao@...inos.cn>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Siddartha Mohanadoss <smohanad@...eaurora.org>,
        Sujeev Dias <sdias@...eaurora.org>,
        Julia Lawall <julia.lawall@...6.fr>, John Crispin <john@...ozen.org>,
        Muna Sinada <quic_msinada@...cinc.com>,
        Venkateswara Naralasetty <quic_vnaralas@...cinc.com>,
        Maharaja Kennadyrajan <quic_mkenna@...cinc.com>, mhi@...ts.linux.dev,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-wireless@...r.kernel.org, ath11k@...ts.infradead.org
Cc: kernel@...labora.com
Subject: Re: [PATCH 3/3] bus: mhi: keep device context through suspend cycles



On 6/30/2025 1:13 PM, Muhammad Usama Anjum wrote:
> Don't deinitialize the device context while going into suspend or
> hibernation cycles. Otherwise the resume may fail if at resume time, the
> memory pressure is high and no dma memory is available.
> 
> Tested-on: WCN6855 WLAN.HSP.1.1-03926.13-QCAHSPSWPL_V2_SILICONZ_CE-2.52297.6
> 
> Fixes: 3000f85b8f47 ("bus: mhi: core: Add support for basic PM operations")
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@...labora.com>
> ---
>   drivers/bus/mhi/host/init.c | 11 ++++++-----
>   1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
> index 2e0f18c939e68..8f56e73fdc42e 100644
> --- a/drivers/bus/mhi/host/init.c
> +++ b/drivers/bus/mhi/host/init.c
> @@ -1133,9 +1133,11 @@ int mhi_prepare_for_power_up(struct mhi_controller *mhi_cntrl)
>   
>   	mutex_lock(&mhi_cntrl->pm_mutex);
>   
> -	ret = mhi_init_dev_ctxt(mhi_cntrl);
mhi init dev ctxt also initializes the ring pointers to base value,
I think we should take care of them also ?

- Krishna Chaitanya.
> -	if (ret)
> -		goto error_dev_ctxt;
> +	if (!mhi_cntrl->mhi_ctxt) {
> +		ret = mhi_init_dev_ctxt(mhi_cntrl);
> +		if (ret)
> +			goto error_dev_ctxt;
> +	}
>   
>   	ret = mhi_read_reg(mhi_cntrl, mhi_cntrl->regs, BHIOFF, &bhi_off);
>   	if (ret) {
> @@ -1212,8 +1214,6 @@ void mhi_deinit_dev_ctxt(struct mhi_controller *mhi_cntrl)
>   {
>   	mhi_cntrl->bhi = NULL;
>   	mhi_cntrl->bhie = NULL;
> -
> -	__mhi_deinit_dev_ctxt(mhi_cntrl);
>   }
>   
>   void mhi_unprepare_after_power_down(struct mhi_controller *mhi_cntrl)
> @@ -1234,6 +1234,7 @@ void mhi_unprepare_after_power_down(struct mhi_controller *mhi_cntrl)
>   	}
>   
>   	mhi_deinit_dev_ctxt(mhi_cntrl);
> +	__mhi_deinit_dev_ctxt(mhi_cntrl);
>   }
>   EXPORT_SYMBOL_GPL(mhi_unprepare_after_power_down);
>