Hi Mani,
On Mon, 8 Nov 2021 at 18:42, Manivannan Sadhasivam
<manivannan.sadhasivam@xxxxxxxxxx> 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>
> ---
> drivers/bus/mhi/core/pm.c | 26 +++++++++++---------------
> 1 file changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index fb99e3727155..ec5f11166820 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -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);
> @@ -1082,19 +1078,18 @@ 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,
Shouldn't we use a polling variant such as mhi_poll_reg_field() given
the interrupts are not yet enabled?
> - 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,
> + 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;
> dev_info(dev, "Failed to reset MHI due to syserr state\n");
> - goto error_async_power_up;
> + goto error_setup_irq;
> }
Regards,
Loic
