bus: mhi: core: Process execution environment changes serially

In current design, whenever the BHI interrupt is fired, the
execution environment is updated. This can cause race conditions
and impede ongoing power up/down processing. For example, if a
power down is in progress, MHI host updates to a local "disabled"
execution environment. If a BHI interrupt fires later, that value
gets replaced with one from the BHI EE register. This impacts the
controller as it does not expect multiple RDDM execution
environment change status callbacks as an example. Another issue
would be that the device can enter mission mode and the execution
environment is updated, while device creation for SBL channels is
still going on due to slower PM state worker thread run, leading
to multiple attempts at opening the same channel.

Ensure that EE changes are handled only from appropriate places
and occur one after another and handle only PBL modes or RDDM EE
changes as critical events directly from the interrupt handler.
Simplify handling by waiting for SYS ERROR before handling RDDM.
This also makes sure that we use the correct execution environment
to notify the controller driver when the device resets to one of
the PBL execution environments.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614208985-20851-4-git-send-email-bbhatt@codeaurora.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 12aacacc6d37ffc09595b05daa7633fc66b0f88e..f3b244a6255a0d3d27a43d720b33fda50e650ea8 100644 (file)
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -430,7 +430,7 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
        enum mhi_state state = MHI_STATE_MAX;
        enum mhi_pm_state pm_state = 0;
-       enum mhi_ee_type ee = 0;
+       enum mhi_ee_type ee = MHI_EE_MAX;
 
        write_lock_irq(&mhi_cntrl->pm_lock);
        if (!MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
@@ -439,8 +439,7 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
        }
 
        state = mhi_get_mhi_state(mhi_cntrl);
-       ee = mhi_cntrl->ee;
-       mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
+       ee = mhi_get_exec_env(mhi_cntrl);
        dev_dbg(dev, "local ee:%s device ee:%s dev_state:%s\n",
                TO_MHI_EXEC_STR(mhi_cntrl->ee), TO_MHI_EXEC_STR(ee),
                TO_MHI_STATE_STR(state));
@@ -452,27 +451,30 @@ irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
        }
        write_unlock_irq(&mhi_cntrl->pm_lock);
 
-        /* If device supports RDDM don't bother processing SYS error */
-       if (mhi_cntrl->rddm_image) {
-               /* host may be performing a device power down already */
-               if (!mhi_is_active(mhi_cntrl))
-                       goto exit_intvec;
+       if (pm_state != MHI_PM_SYS_ERR_DETECT || ee == mhi_cntrl->ee)
+               goto exit_intvec;
 
-               if (mhi_cntrl->ee == MHI_EE_RDDM && mhi_cntrl->ee != ee) {
+       switch (ee) {
+       case MHI_EE_RDDM:
+               /* proceed if power down is not already in progress */
+               if (mhi_cntrl->rddm_image && mhi_is_active(mhi_cntrl)) {
                        mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_EE_RDDM);
+                       mhi_cntrl->ee = ee;
                        wake_up_all(&mhi_cntrl->state_event);
                }
-               goto exit_intvec;
-       }
-
-       if (pm_state == MHI_PM_SYS_ERR_DETECT) {
+               break;
+       case MHI_EE_PBL:
+       case MHI_EE_EDL:
+       case MHI_EE_PTHRU:
+               mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_FATAL_ERROR);
+               mhi_cntrl->ee = ee;
                wake_up_all(&mhi_cntrl->state_event);
-
-               /* For fatal errors, we let controller decide next step */
-               if (MHI_IN_PBL(ee))
-                       mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_FATAL_ERROR);
-               else
-                       mhi_pm_sys_err_handler(mhi_cntrl);
+               mhi_pm_sys_err_handler(mhi_cntrl);
+               break;
+       default:
+               wake_up_all(&mhi_cntrl->state_event);
+               mhi_pm_sys_err_handler(mhi_cntrl);
+               break;
        }
 
 exit_intvec:

diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index 59ef2d5e3d90aa5baf3c6f0ac48c0834ffb91210..b4ee9295e7affa1a02f297033c6e9f30582c7688 100644 (file)
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -377,21 +377,22 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
 {
        struct mhi_event *mhi_event;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
-       enum mhi_ee_type current_ee = mhi_cntrl->ee;
+       enum mhi_ee_type ee = MHI_EE_MAX, current_ee = mhi_cntrl->ee;
        int i, ret;
 
        dev_dbg(dev, "Processing Mission Mode transition\n");
 
        write_lock_irq(&mhi_cntrl->pm_lock);
        if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state))
-               mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
+               ee = mhi_get_exec_env(mhi_cntrl);
 
-       if (!MHI_IN_MISSION_MODE(mhi_cntrl->ee)) {
+       if (!MHI_IN_MISSION_MODE(ee)) {
                mhi_cntrl->pm_state = MHI_PM_LD_ERR_FATAL_DETECT;
                write_unlock_irq(&mhi_cntrl->pm_lock);
                wake_up_all(&mhi_cntrl->state_event);
                return -EIO;
        }
+       mhi_cntrl->ee = ee;
        write_unlock_irq(&mhi_cntrl->pm_lock);
 
        wake_up_all(&mhi_cntrl->state_event);