Hey Loic,
On Mon, Nov 08, 2021 at 07:04:56PM +0100, Loic Poulain wrote:
> 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?
>
Realised _just_ after sending the patch and already submitted v2. Please take a
look.
Thanks,
Mani
> > - 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
