Re: [PATCH v2 1/5] bus: mhi: core: Handle syserr during power_up

[Hemant Kumar <hemantk@codeaurora.org>]

On 4/7/20 9:50 AM, 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@codeaurora.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..3285c9e 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,
> +					 mhi_cntrl->timeout_ms * 1000);
can we use this instead of polling because MSI is configures and int_vec 
handler is registered

     wait_event_timeout(mhi_cntrl->state_event,
                MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
               mhi_read_reg_field(mhi_cntrl, base, MHICTRL,
                           MHICTRL_RESET_MASK,
                           MHICTRL_RESET_SHIFT, &reset) || !reset ,
                msecs_to_jiffies(mhi_cntrl->timeout_ms));

1) In case of MHI_PM_IN_FATAL_STATE we would not be accessing MHI reg
2) Consistent with current MHI driver code.
> +		if (ret) {
> +			dev_info(dev, "Failed to reset MHI due to syserr state\n");
> +			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;

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