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bus: mhi: core: Mark and maintain device states early on after power down
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>
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556bbb442b
commit
a03c7a86e1
1 changed files with 33 additions and 44 deletions
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@ -37,9 +37,10 @@
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* M0 -> FW_DL_ERR
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* M0 -> M3_ENTER -> M3 -> M3_EXIT --> M0
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* L1: SYS_ERR_DETECT -> SYS_ERR_PROCESS --> POR
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* L2: SHUTDOWN_PROCESS -> DISABLE
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* L2: SHUTDOWN_PROCESS -> LD_ERR_FATAL_DETECT
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* SHUTDOWN_PROCESS -> DISABLE
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* L3: LD_ERR_FATAL_DETECT <--> LD_ERR_FATAL_DETECT
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* LD_ERR_FATAL_DETECT -> SHUTDOWN_PROCESS
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* LD_ERR_FATAL_DETECT -> DISABLE
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*/
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static struct mhi_pm_transitions const dev_state_transitions[] = {
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/* L0 States */
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@ -72,7 +73,7 @@ static struct mhi_pm_transitions const dev_state_transitions[] = {
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{
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MHI_PM_M3,
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MHI_PM_M3_EXIT | MHI_PM_SYS_ERR_DETECT |
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MHI_PM_SHUTDOWN_PROCESS | MHI_PM_LD_ERR_FATAL_DETECT
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MHI_PM_LD_ERR_FATAL_DETECT
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},
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{
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MHI_PM_M3_EXIT,
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@ -103,7 +104,7 @@ static struct mhi_pm_transitions const dev_state_transitions[] = {
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/* L3 States */
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{
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MHI_PM_LD_ERR_FATAL_DETECT,
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MHI_PM_LD_ERR_FATAL_DETECT | MHI_PM_SHUTDOWN_PROCESS
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MHI_PM_LD_ERR_FATAL_DETECT | MHI_PM_DISABLE
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},
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};
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@ -445,10 +446,9 @@ static int mhi_pm_mission_mode_transition(struct mhi_controller *mhi_cntrl)
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}
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/* Handle shutdown transitions */
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static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl,
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enum mhi_pm_state transition_state)
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static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl)
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{
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enum mhi_pm_state cur_state, prev_state;
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enum mhi_pm_state cur_state;
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struct mhi_event *mhi_event;
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struct mhi_cmd_ctxt *cmd_ctxt;
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struct mhi_cmd *mhi_cmd;
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@ -456,33 +456,13 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl,
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struct device *dev = &mhi_cntrl->mhi_dev->dev;
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int ret, i;
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dev_dbg(dev, "Transitioning from PM state: %s to: %s\n",
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to_mhi_pm_state_str(mhi_cntrl->pm_state),
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to_mhi_pm_state_str(transition_state));
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dev_dbg(dev, "Processing disable transition with PM state: %s\n",
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to_mhi_pm_state_str(mhi_cntrl->pm_state));
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mutex_lock(&mhi_cntrl->pm_mutex);
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write_lock_irq(&mhi_cntrl->pm_lock);
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prev_state = mhi_cntrl->pm_state;
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cur_state = mhi_tryset_pm_state(mhi_cntrl, transition_state);
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if (cur_state == transition_state) {
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mhi_cntrl->ee = MHI_EE_DISABLE_TRANSITION;
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mhi_cntrl->dev_state = MHI_STATE_RESET;
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}
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write_unlock_irq(&mhi_cntrl->pm_lock);
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/* Wake up threads waiting for state transition */
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wake_up_all(&mhi_cntrl->state_event);
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if (cur_state != transition_state) {
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dev_err(dev, "Failed to transition to state: %s from: %s\n",
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to_mhi_pm_state_str(transition_state),
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to_mhi_pm_state_str(cur_state));
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mutex_unlock(&mhi_cntrl->pm_mutex);
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return;
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}
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/* Trigger MHI RESET so that the device will not access host memory */
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if (MHI_REG_ACCESS_VALID(prev_state)) {
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if (!MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state)) {
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u32 in_reset = -1;
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unsigned long timeout = msecs_to_jiffies(mhi_cntrl->timeout_ms);
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@ -785,8 +765,7 @@ void mhi_pm_st_worker(struct work_struct *work)
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mhi_pm_sys_error_transition(mhi_cntrl);
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break;
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case DEV_ST_TRANSITION_DISABLE:
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mhi_pm_disable_transition
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(mhi_cntrl, MHI_PM_SHUTDOWN_PROCESS);
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mhi_pm_disable_transition(mhi_cntrl);
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break;
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default:
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break;
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@ -1153,23 +1132,33 @@ EXPORT_SYMBOL_GPL(mhi_async_power_up);
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void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
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{
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enum mhi_pm_state cur_state;
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enum mhi_pm_state cur_state, transition_state;
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struct device *dev = &mhi_cntrl->mhi_dev->dev;
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/* If it's not a graceful shutdown, force MHI to linkdown state */
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if (!graceful) {
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mutex_lock(&mhi_cntrl->pm_mutex);
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write_lock_irq(&mhi_cntrl->pm_lock);
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cur_state = mhi_tryset_pm_state(mhi_cntrl,
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MHI_PM_LD_ERR_FATAL_DETECT);
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write_unlock_irq(&mhi_cntrl->pm_lock);
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mutex_unlock(&mhi_cntrl->pm_mutex);
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if (cur_state != MHI_PM_LD_ERR_FATAL_DETECT)
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dev_dbg(dev, "Failed to move to state: %s from: %s\n",
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to_mhi_pm_state_str(MHI_PM_LD_ERR_FATAL_DETECT),
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to_mhi_pm_state_str(mhi_cntrl->pm_state));
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transition_state = (graceful) ? MHI_PM_SHUTDOWN_PROCESS :
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MHI_PM_LD_ERR_FATAL_DETECT;
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mutex_lock(&mhi_cntrl->pm_mutex);
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write_lock_irq(&mhi_cntrl->pm_lock);
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cur_state = mhi_tryset_pm_state(mhi_cntrl, transition_state);
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if (cur_state != transition_state) {
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dev_err(dev, "Failed to move to state: %s from: %s\n",
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to_mhi_pm_state_str(transition_state),
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to_mhi_pm_state_str(mhi_cntrl->pm_state));
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/* Force link down or error fatal detected state */
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mhi_cntrl->pm_state = MHI_PM_LD_ERR_FATAL_DETECT;
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}
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/* mark device inactive to avoid any further host processing */
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mhi_cntrl->ee = MHI_EE_DISABLE_TRANSITION;
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mhi_cntrl->dev_state = MHI_STATE_RESET;
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wake_up_all(&mhi_cntrl->state_event);
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write_unlock_irq(&mhi_cntrl->pm_lock);
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mutex_unlock(&mhi_cntrl->pm_mutex);
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mhi_queue_state_transition(mhi_cntrl, DEV_ST_TRANSITION_DISABLE);
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/* Wait for shutdown to complete */
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