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Subject: Re: [PATCH] bus: mhi: core: Add support for forced PM resume
To:     Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        mhi@lists.linux.dev
Cc:     bbhatt@codeaurora.org, loic.poulain@linaro.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        ath11k@lists.infradead.org, linux-wireless@vger.kernel.org,
        kvalo@codeaurora.org, stable@vger.kernel.org,
        Pengyu Ma <mapengyu@gmail.com>
References: <20211206161059.107007-1-manivannan.sadhasivam@linaro.org>
From:   Hemant Kumar <hemantk@codeaurora.org>
Message-ID: <7eb05d7c-ddda-5ec1-73a0-e696d2b5a236@codeaurora.org>
Date:   Tue, 7 Dec 2021 15:41:42 -0800
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Hi Mani,

On 12/6/2021 8:10 AM, Manivannan Sadhasivam wrote:
> From: Loic Poulain <loic.poulain@linaro.org>
> 
> For whatever reason, some devices like QCA6390, WCN6855 using ath11k
> are not in M3 state during PM resume, but still functional. The
> mhi_pm_resume should then not fail in those cases, and let the higher
> level device specific stack continue resuming process.
> 
> Add a new parameter to mhi_pm_resume, to force resuming, whatever the
> current MHI state is. This fixes a regression with non functional
> ath11k WiFi after suspend/resume cycle on some machines.
> 
> Bug report: https://bugzilla.kernel.org/show_bug.cgi?id=214179
> 
> Cc: stable@vger.kernel.org #5.13
> Fixes: 020d3b26c07a ("bus: mhi: Early MHI resume failure in non M3 state")
> Reported-by: Kalle Valo <kvalo@codeaurora.org>
> Reported-by: Pengyu Ma <mapengyu@gmail.com>
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> [mani: Added comment, bug report, added reported-by tags and CCed stable]
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
>   drivers/bus/mhi/core/pm.c             | 10 +++++++---
>   drivers/bus/mhi/pci_generic.c         |  2 +-
>   drivers/net/wireless/ath/ath11k/mhi.c |  6 +++++-
>   include/linux/mhi.h                   |  3 ++-
>   4 files changed, 15 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index 7464f5d09973..4ddd266e042e 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -881,7 +881,7 @@ int mhi_pm_suspend(struct mhi_controller *mhi_cntrl)
>   }
>   EXPORT_SYMBOL_GPL(mhi_pm_suspend);
>   
> -int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
> +int mhi_pm_resume(struct mhi_controller *mhi_cntrl, bool force)
>   {
>   	struct mhi_chan *itr, *tmp;
>   	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> @@ -898,8 +898,12 @@ int mhi_pm_resume(struct mhi_controller *mhi_cntrl)
>   	if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state))
>   		return -EIO;
>   
> -	if (mhi_get_mhi_state(mhi_cntrl) != MHI_STATE_M3)
> -		return -EINVAL;
> +	if (mhi_get_mhi_state(mhi_cntrl) != MHI_STATE_M3) {
	in case if mhi_get_mhi_state(mhi_cntrl) returns SYS_ERR (assuming while 
doing this check SYS_ERR is set) do we still want to continue pm resume 
when force is true? Just want to make sure SYS_ERR handling with and 
without this change remains the same or atleast does not cause any 
regression with this change. or if we need to continue pm resume only 
for MHI_STATE_RESET when MHI_STATE_M3 is not set?
> +		dev_warn(dev, "Resuming from non M3 state (%s)\n",
> +			 TO_MHI_STATE_STR(mhi_get_mhi_state(mhi_cntrl)));
> +		if (!force)
> +			return -EINVAL;
> +	}
>   
[..]

Thanks,
Hemant
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