When processing a SYSERR, if the device does not respond to the MHI_RESET
from the host, the host will be stuck in a difficult to recover state.
The host will remain in MHI_PM_SYS_ERR_PROCESS and not clean up the host
channels. Clients will not be notified of the SYSERR via the destruction
of their channel devices, which means clients may think that the device is
still up. Subsequent SYSERR events such as a device fatal error will not
be processed as the state machine cannot transition from PROCESS back to
DETECT. The only way to recover from this is to unload the mhi module
(wipe the state machine state) or for the mhi controller to initiate
SHUTDOWN.
In this failure case, to recover the device, we need a state similar to
PROCESS, but can transition to DETECT. There is not a viable existing
state to use. POR has the needed transitions, but assumes the device is
in a good state and could allow the host to attempt to use the device.
Allowing PROCESS to transition to DETECT invites the possibility of
parallel SYSERR processing which could get the host and device out of
sync.
Thus, invent a new state - MHI_PM_SYS_ERR_FAIL
This essentially a holding state. It allows us to clean up the host
elements that are based on the old state of the device (channels), but
does not allow us to directly advance back to an operational state. It
does allow the detection and processing of another SYSERR which may
recover the device, or allows the controller to do a clean shutdown.
Signed-off-by: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
Reviewed-by: Carl Vanderlip <quic_carlv@xxxxxxxxxxx>
---
drivers/bus/mhi/host/init.c | 1 +
drivers/bus/mhi/host/internal.h | 9 ++++++---
drivers/bus/mhi/host/pm.c | 20 +++++++++++++++++---
3 files changed, 24 insertions(+), 6 deletions(-)
diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
index e2c2f510b04f..d3f919277cf9 100644
--- a/drivers/bus/mhi/host/init.c
+++ b/drivers/bus/mhi/host/init.c
@@ -62,6 +62,7 @@ static const char * const mhi_pm_state_str[] = {
[MHI_PM_STATE_FW_DL_ERR] = "Firmware Download Error",
[MHI_PM_STATE_SYS_ERR_DETECT] = "SYS ERROR Detect",
[MHI_PM_STATE_SYS_ERR_PROCESS] = "SYS ERROR Process",
+ [MHI_PM_STATE_SYS_ERR_FAIL] = "SYS ERROR Failure",
[MHI_PM_STATE_SHUTDOWN_PROCESS] = "SHUTDOWN Process",
[MHI_PM_STATE_LD_ERR_FATAL_DETECT] = "Linkdown or Error Fatal Detect",
};
diff --git a/drivers/bus/mhi/host/internal.h b/drivers/bus/mhi/host/internal.h
index 30ac415a3000..4b6deea17bcd 100644
--- a/drivers/bus/mhi/host/internal.h
+++ b/drivers/bus/mhi/host/internal.h
@@ -88,6 +88,7 @@ enum mhi_pm_state {
MHI_PM_STATE_FW_DL_ERR,
MHI_PM_STATE_SYS_ERR_DETECT,
MHI_PM_STATE_SYS_ERR_PROCESS,
+ MHI_PM_STATE_SYS_ERR_FAIL,
MHI_PM_STATE_SHUTDOWN_PROCESS,
MHI_PM_STATE_LD_ERR_FATAL_DETECT,
MHI_PM_STATE_MAX
@@ -104,14 +105,16 @@ enum mhi_pm_state {
#define MHI_PM_FW_DL_ERR BIT(7)
#define MHI_PM_SYS_ERR_DETECT BIT(8)
#define MHI_PM_SYS_ERR_PROCESS BIT(9)
-#define MHI_PM_SHUTDOWN_PROCESS BIT(10)
+#define MHI_PM_SYS_ERR_FAIL BIT(10)
+#define MHI_PM_SHUTDOWN_PROCESS BIT(11)
/* link not accessible */
-#define MHI_PM_LD_ERR_FATAL_DETECT BIT(11)
+#define MHI_PM_LD_ERR_FATAL_DETECT BIT(12)
#define MHI_REG_ACCESS_VALID(pm_state) ((pm_state & (MHI_PM_POR | MHI_PM_M0 | \
MHI_PM_M2 | MHI_PM_M3_ENTER | MHI_PM_M3_EXIT | \
MHI_PM_SYS_ERR_DETECT | MHI_PM_SYS_ERR_PROCESS | \
- MHI_PM_SHUTDOWN_PROCESS | MHI_PM_FW_DL_ERR)))
+ MHI_PM_SYS_ERR_FAIL | MHI_PM_SHUTDOWN_PROCESS | \
+ MHI_PM_FW_DL_ERR)))
#define MHI_PM_IN_ERROR_STATE(pm_state) (pm_state >= MHI_PM_FW_DL_ERR)
#define MHI_PM_IN_FATAL_STATE(pm_state) (pm_state == MHI_PM_LD_ERR_FATAL_DETECT)
#define MHI_DB_ACCESS_VALID(mhi_cntrl) (mhi_cntrl->pm_state & mhi_cntrl->db_access)
diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c
index a2f2feef1476..d0d033ce9984 100644
--- a/drivers/bus/mhi/host/pm.c
+++ b/drivers/bus/mhi/host/pm.c
@@ -36,7 +36,10 @@
* M0 <--> M0
* M0 -> FW_DL_ERR
* M0 -> M3_ENTER -> M3 -> M3_EXIT --> M0
- * L1: SYS_ERR_DETECT -> SYS_ERR_PROCESS --> POR
+ * L1: SYS_ERR_DETECT -> SYS_ERR_PROCESS
+ * SYS_ERR_PROCESS -> SYS_ERR_FAIL
+ * SYS_ERR_FAIL -> SYS_ERR_DETECT
+ * SYS_ERR_PROCESS --> POR
* L2: SHUTDOWN_PROCESS -> LD_ERR_FATAL_DETECT
* SHUTDOWN_PROCESS -> DISABLE
* L3: LD_ERR_FATAL_DETECT <--> LD_ERR_FATAL_DETECT
@@ -93,7 +96,12 @@ static const struct mhi_pm_transitions dev_state_transitions[] = {
},
{
MHI_PM_SYS_ERR_PROCESS,
- MHI_PM_POR | MHI_PM_SHUTDOWN_PROCESS |
+ MHI_PM_POR | MHI_PM_SYS_ERR_FAIL | MHI_PM_SHUTDOWN_PROCESS |
+ MHI_PM_LD_ERR_FATAL_DETECT
+ },
+ {
+ MHI_PM_SYS_ERR_FAIL,
+ MHI_PM_SYS_ERR_DETECT | MHI_PM_SHUTDOWN_PROCESS |
MHI_PM_LD_ERR_FATAL_DETECT
},
/* L2 States */
@@ -629,7 +637,13 @@ static void mhi_pm_sys_error_transition(struct mhi_controller *mhi_cntrl)
!in_reset, timeout);
if (!ret || in_reset) {
dev_err(dev, "Device failed to exit MHI Reset state\n");
- goto exit_sys_error_transition;
+ write_lock_irq(&mhi_cntrl->pm_lock);
+ cur_state = mhi_tryset_pm_state(mhi_cntrl,
+ MHI_PM_SYS_ERR_FAIL);
+ write_unlock_irq(&mhi_cntrl->pm_lock);
+ /* Shutdown may have occurred, otherwise cleanup now */
+ if (cur_state != MHI_PM_SYS_ERR_FAIL)
+ goto exit_sys_error_transition;
}
/*
--
2.34.1
