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bus: mhi: core: Mark and maintain device states early on after power down

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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@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
This commit is contained in:
Bhaumik Bhatt 2020-11-09 12:47:30 -08:00 committed by Manivannan Sadhasivam
parent 556bbb442b
commit a03c7a86e1
No known key found for this signature in database
GPG Key ID: 559F11E6FE91CEF5
1 changed files with 33 additions and 44 deletions
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77
drivers/bus/mhi/core/pm.c
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@ -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 @@ error_mission_mode:
}
/* 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 */