During SYS_ERR condition, as a response to the MHI_RESET from host, some devices tend to issue BHI interrupt without clearing the SYS_ERR state in the device. 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 the BHI interrupt to the host without clearing SYS_ERR condition. So the host starts handling the SYS_ERR condition again.

To fix this issue, let's register the IRQ handler only after handling the SYS_ERR check to avoid getting spurious IRQs from the device.

Cc: stable@vger.kernel.org Fixes: e18d4e9fa79b ("bus: mhi: core: Handle syserr during power_up") Reported-by: Aleksander Morgado aleksander@aleksander.es Tested-by: Aleksander Morgado aleksander@aleksander.es Tested-by: Thomas Perrot thomas.perrot@bootlin.com Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org --- drivers/bus/mhi/core/pm.c | 35 ++++++++++++----------------------- 1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c index 7464f5d09973..9ae8532df5a3 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_exit; }

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_exit; }

/* @@ -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_exit; + /* Transition to next state */ next_state = MHI_IN_PBL(current_ee) ? DEV_ST_TRANSITION_PBL : DEV_ST_TRANSITION_READY; @@ -1116,10 +1108,7 @@ 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: +error_exit: mhi_cntrl->pm_state = MHI_PM_DISABLE; mutex_unlock(&mhi_cntrl->pm_mutex);