linux-kernel - Re: [PATCH 1/3] bus: mhi: core: Handle syserr during power

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Message-ID: <20200407062641.GC2442@Mani-XPS-13-9360>
Date:   Tue, 7 Apr 2020 11:56:41 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Jeffrey Hugo <jhugo@...eaurora.org>
Cc:     hemantk@...eaurora.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] bus: mhi: core: Handle syserr during power_up

On Mon, Apr 06, 2020 at 03:04:35PM -0600, Jeffrey Hugo wrote:
> The MHI device may be in the syserr state when we attempt to init it in
> power_up().  Since we have no local state, the handling is simple -
> reset the device and wait for it to transition out of the reset state.
> 
> Signed-off-by: Jeffrey Hugo <jhugo@...eaurora.org>
> ---
>  drivers/bus/mhi/core/pm.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index 52690cb..cd6ba23 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -9,6 +9,7 @@
>  #include <linux/dma-direction.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/interrupt.h>
> +#include <linux/iopoll.h>
>  #include <linux/list.h>
>  #include <linux/mhi.h>
>  #include <linux/module.h>
> @@ -760,6 +761,7 @@ static void mhi_deassert_dev_wake(struct mhi_controller *mhi_cntrl,
>  
>  int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
>  {
> +	enum mhi_state state;
>  	enum mhi_ee_type current_ee;
>  	enum dev_st_transition next_state;
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> @@ -829,6 +831,24 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
>  		goto error_bhi_offset;
>  	}
>  
> +	state = mhi_get_mhi_state(mhi_cntrl);
> +	if (state == MHI_STATE_SYS_ERR) {
> +		mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
> +		ret = readl_poll_timeout(mhi_cntrl->regs + MHICTRL, val,
> +					 !(val & MHICTRL_RESET_MASK), 1000,

Hmm. Do we really need a max 1ms delay between each read? I'd prefer to have
100ns to reduce the wait time.

> +					 mhi_cntrl->timeout_ms * 1000);
> +		if (ret) {
> +			dev_info(dev, "Failed to reset syserr\n");

dev_info(dev, "Failed to reset MHI due to syserr state\n"); ?

Thanks,
Mani

> +			goto error_bhi_offset;
> +		}
> +
> +		/*
> +		 * device cleares INTVEC as part of RESET processing,
> +		 * re-program it
> +		 */
> +		mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
> +	}
> +
>  	/* Transition to next state */
>  	next_state = MHI_IN_PBL(current_ee) ?
>  		DEV_ST_TRANSITION_PBL : DEV_ST_TRANSITION_READY;
> -- 
> Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.