On Wed, Nov 24, 2021 at 06:52:21PM +0530, Manivannan Sadhasivam wrote:
> Some devices tend to trigger SYS_ERR interrupt while the host handling
> SYS_ERR state of the device during power up. This creates a race
> condition and causes a failure in booting up the device.
>
> The issue is seen on the Sierra Wireless EM9191 modem during SYS_ERR
> handling in mhi_async_power_up(). Once the host detects that the device
> is in SYS_ERR state, it issues MHI_RESET and waits for the device to
> process the reset request. During this time, the device triggers SYS_ERR
> interrupt to the host and host starts handling SYS_ERR execution.
>
> So by the time the device has completed reset, host starts SYS_ERR
> handling. This causes the race condition and the modem fails to boot.
>
> Hence, register the IRQ handler only after handling the SYS_ERR check
> to avoid getting spurious IRQs from the device.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: e18d4e9fa79b ("bus: mhi: core: Handle syserr during power_up")
> Reported-by: Aleksander Morgado <aleksander@xxxxxxxxxxxxx>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
Hemant, Bhaumik, Jeff: Can you please do the review again?
Thanks,
Mani
> ---
>
> Changes in v4:
>
> * Reverted the change that moved BHI_INTVEC as that was causing issue as
> reported by Aleksander.
>
> Changes in v3:
>
> * Moved BHI_INTVEC setup after irq setup
> * Used interval_us as the delay for the polling API
>
> Changes in v2:
>
> * Switched to "mhi_poll_reg_field" for detecting MHI reset in device.
>
> drivers/bus/mhi/core/pm.c | 33 +++++++++++----------------------
> 1 file changed, 11 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index fb99e3727155..21484a61bbed 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -1038,7 +1038,7 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> enum mhi_ee_type current_ee;
> enum dev_st_transition next_state;
> struct device *dev = &mhi_cntrl->mhi_dev->dev;
> - u32 val;
> + u32 interval_us = 25000; /* poll register field every 25 milliseconds */
> int ret;
>
> dev_info(dev, "Requested to power ON\n");
> @@ -1055,10 +1055,6 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> mutex_lock(&mhi_cntrl->pm_mutex);
> mhi_cntrl->pm_state = MHI_PM_DISABLE;
>
> - ret = mhi_init_irq_setup(mhi_cntrl);
> - if (ret)
> - goto error_setup_irq;
> -
> /* Setup BHI INTVEC */
> write_lock_irq(&mhi_cntrl->pm_lock);
> mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
> @@ -1072,7 +1068,7 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> dev_err(dev, "%s is not a valid EE for power on\n",
> TO_MHI_EXEC_STR(current_ee));
> ret = -EIO;
> - goto error_async_power_up;
> + goto error_setup_irq;
> }
>
> state = mhi_get_mhi_state(mhi_cntrl);
> @@ -1081,20 +1077,12 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
>
> if (state == MHI_STATE_SYS_ERR) {
> mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
> - ret = wait_event_timeout(mhi_cntrl->state_event,
> - MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
> - mhi_read_reg_field(mhi_cntrl,
> - mhi_cntrl->regs,
> - MHICTRL,
> - MHICTRL_RESET_MASK,
> - MHICTRL_RESET_SHIFT,
> - &val) ||
> - !val,
> - msecs_to_jiffies(mhi_cntrl->timeout_ms));
> - if (!ret) {
> - ret = -EIO;
> + ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, MHICTRL,
> + MHICTRL_RESET_MASK, MHICTRL_RESET_SHIFT, 0,
> + interval_us);
> + if (ret) {
> dev_info(dev, "Failed to reset MHI due to syserr state\n");
> - goto error_async_power_up;
> + goto error_setup_irq;
> }
>
> /*
> @@ -1104,6 +1092,10 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
> }
>
> + ret = mhi_init_irq_setup(mhi_cntrl);
> + if (ret)
> + goto error_setup_irq;
> +
> /* Transition to next state */
> next_state = MHI_IN_PBL(current_ee) ?
> DEV_ST_TRANSITION_PBL : DEV_ST_TRANSITION_READY;
> @@ -1116,9 +1108,6 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
>
> return 0;
>
> -error_async_power_up:
> - mhi_deinit_free_irq(mhi_cntrl);
> -
> error_setup_irq:
> mhi_cntrl->pm_state = MHI_PM_DISABLE;
> mutex_unlock(&mhi_cntrl->pm_mutex);
> --
> 2.25.1
>
