Commit d651ce8e authored by Manivannan Sadhasivam's avatar Manivannan Sadhasivam Committed by Greg Kroah-Hartman
Browse files

bus: mhi: core: Fix race while handling SYS_ERR at power up 



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.

Fixes: e18d4e9f ("bus: mhi: core: Handle syserr during power_up")
Cc: stable@vger.kernel.org
Reported-by: default avatarAleksander Morgado <aleksander@aleksander.es>
Tested-by: default avatarAleksander Morgado <aleksander@aleksander.es>
Tested-by: default avatarThomas Perrot <thomas.perrot@bootlin.com>
Signed-off-by: default avatarManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20211216081227.237749-8-manivannan.sadhasivam@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 42c4668f

drivers/bus/mhi/core/pm.c

+12 −23
Original line number Diff line number Diff line
@@ -1053,7 +1053,7 @@ 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");
@@ -1070,10 +1070,6 @@ 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);
@@ -1087,7 +1083,7 @@ 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);
@@ -1096,20 +1092,12 @@ 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;

		}



		/*
@@ -1119,6 +1107,10 @@ 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;
@@ -1131,10 +1123,7 @@ 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);