mhi_power_down() does not ensure that the PM state is moved to an
inaccessible state soon enough as the system can encounter
scheduling delays till mhi_pm_disable_transition() gets called.
Additionally, if an MHI controller decides that the device is now
inaccessible and issues a power down, the register inaccessible
state is not maintained by moving from MHI_PM_LD_ERR_FATAL_DETECT
to MHI_PM_SHUTDOWN_PROCESS. This can result in bus errors if a
client driver attempted to read registers when powering down.
Close these gaps and avoid any race conditions to prevent such
activity.
Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
---
drivers/bus/mhi/core/pm.c | 77 ++++++++++++++++++++---------------------------
1 file changed, 33 insertions(+), 44 deletions(-)
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index 347ae7d..ffbf6f5 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -37,9 +37,10 @@
* M0 -> FW_DL_ERR
* M0 -> M3_ENTER -> M3 -> M3_EXIT --> M0
* L1: SYS_ERR_DETECT -> SYS_ERR_PROCESS --> POR
- * L2: SHUTDOWN_PROCESS -> DISABLE
+ * L2: SHUTDOWN_PROCESS -> LD_ERR_FATAL_DETECT
+ * SHUTDOWN_PROCESS -> DISABLE
* L3: LD_ERR_FATAL_DETECT <--> LD_ERR_FATAL_DETECT
- * LD_ERR_FATAL_DETECT -> SHUTDOWN_PROCESS
+ * LD_ERR_FATAL_DETECT -> DISABLE
*/
static struct mhi_pm_transitions const dev_state_transitions[] = {
/* L0 States */
@@ -72,7 +73,7 @@ static struct mhi_pm_transitions const dev_state_transitions[] = {
{
MHI_PM_M3,
MHI_PM_M3_EXIT | MHI_PM_SYS_ERR_DETECT |
- MHI_PM_SHUTDOWN_PROCESS | MHI_PM_LD_ERR_FATAL_DETECT
+ MHI_PM_LD_ERR_FATAL_DETECT
},
{
MHI_PM_M3_EXIT,
@@ -103,7 +104,7 @@ static struct mhi_pm_transitions const dev_state_transitions[] = {
/* L3 States */
{
MHI_PM_LD_ERR_FATAL_DETECT,
- MHI_PM_LD_ERR_FATAL_DETECT | MHI_PM_SHUTDOWN_PROCESS
+ MHI_PM_LD_ERR_FATAL_DETECT | MHI_PM_DISABLE
},
};
@@ -445,10 +446,9 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
}
/* Handle shutdown transitions */
-static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl,
- enum mhi_pm_state transition_state)
+static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
{
- enum mhi_pm_state cur_state, prev_state;
+ enum mhi_pm_state cur_state;
struct mhi_event *mhi_event;
struct mhi_cmd_ctxt *cmd_ctxt;
struct mhi_cmd *mhi_cmd;
@@ -456,33 +456,13 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl,
struct device *dev = &mhi_cntrl->mhi_dev->dev;
int ret, i;
- dev_dbg(dev, "Transitioning from PM state: %s to: %s\n",
- to_mhi_pm_state_str(mhi_cntrl->pm_state),
- to_mhi_pm_state_str(transition_state));
+ dev_dbg(dev, "Processing disable transition with PM state: %s\n",
+ to_mhi_pm_state_str(mhi_cntrl->pm_state));
mutex_lock(&mhi_cntrl->pm_mutex);
- write_lock_irq(&mhi_cntrl->pm_lock);
- prev_state = mhi_cntrl->pm_state;
- cur_state = mhi_tryset_pm_state(mhi_cntrl, transition_state);
- if (cur_state == transition_state) {
- mhi_cntrl->ee = MHI_EE_DISABLE_TRANSITION;
- mhi_cntrl->dev_state = MHI_STATE_RESET;
- }
- write_unlock_irq(&mhi_cntrl->pm_lock);
-
- /* Wake up threads waiting for state transition */
- wake_up_all(&mhi_cntrl->state_event);
-
- if (cur_state != transition_state) {
- dev_err(dev, "Failed to transition to state: %s from: %s\n",
- to_mhi_pm_state_str(transition_state),
- to_mhi_pm_state_str(cur_state));
- mutex_unlock(&mhi_cntrl->pm_mutex);
- return;
- }
/* Trigger MHI RESET so that the device will not access host memory */
- if (MHI_REG_ACCESS_VALID(prev_state)) {
+ if (!MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
u32 in_reset = -1;
unsigned long timeout = msecs_to_jiffies(mhi_cntrl->timeout_ms);
@@ -785,8 +765,7 @@ void mhi_pm_st_worker(struct work_struct *work)
mhi_pm_sys_error_transition(mhi_cntrl);
break;
case DEV_ST_TRANSITION_DISABLE:
- mhi_pm_disable_transition
- (mhi_cntrl, MHI_PM_SHUTDOWN_PROCESS);
+ mhi_pm_disable_transition(mhi_cntrl);
break;
default:
break;
@@ -1153,23 +1132,33 @@ EXPORT_SYMBOL_GPL(mhi_async_power_up);
void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
{
- enum mhi_pm_state cur_state;
+ enum mhi_pm_state cur_state, transition_state;
struct device *dev = &mhi_cntrl->mhi_dev->dev;
/* If it's not a graceful shutdown, force MHI to linkdown state */
- if (!graceful) {
- mutex_lock(&mhi_cntrl->pm_mutex);
- write_lock_irq(&mhi_cntrl->pm_lock);
- cur_state = mhi_tryset_pm_state(mhi_cntrl,
- MHI_PM_LD_ERR_FATAL_DETECT);
- write_unlock_irq(&mhi_cntrl->pm_lock);
- mutex_unlock(&mhi_cntrl->pm_mutex);
- if (cur_state != MHI_PM_LD_ERR_FATAL_DETECT)
- dev_dbg(dev, "Failed to move to state: %s from: %s\n",
- to_mhi_pm_state_str(MHI_PM_LD_ERR_FATAL_DETECT),
- to_mhi_pm_state_str(mhi_cntrl->pm_state));
+ transition_state = (graceful) ? MHI_PM_SHUTDOWN_PROCESS :
+ MHI_PM_LD_ERR_FATAL_DETECT;
+
+ mutex_lock(&mhi_cntrl->pm_mutex);
+ write_lock_irq(&mhi_cntrl->pm_lock);
+ cur_state = mhi_tryset_pm_state(mhi_cntrl, transition_state);
+ if (cur_state != transition_state) {
+ dev_err(dev, "Failed to move to state: %s from: %s\n",
+ to_mhi_pm_state_str(transition_state),
+ to_mhi_pm_state_str(mhi_cntrl->pm_state));
+ /* Force link down or error fatal detected state */
+ mhi_cntrl->pm_state = MHI_PM_LD_ERR_FATAL_DETECT;
}
+ /* mark device inactive to avoid any further host processing */
+ mhi_cntrl->ee = MHI_EE_DISABLE_TRANSITION;
+ mhi_cntrl->dev_state = MHI_STATE_RESET;
+
+ wake_up_all(&mhi_cntrl->state_event);
+
+ write_unlock_irq(&mhi_cntrl->pm_lock);
+ mutex_unlock(&mhi_cntrl->pm_mutex);
+
mhi_queue_state_transition(mhi_cntrl, DEV_ST_TRANSITION_DISABLE);
/* Wait for shutdown to complete */
--
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