Re: [PATCH v3 10/12] bus: mhi: core: Separate system error and power down handling

From: Manivannan Sadhasivam
Date: Sat Oct 31 2020 - 03:12:15 EST

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In reply to: Bhaumik Bhatt: "Re: [PATCH v3 10/12] bus: mhi: core: Separate system error and power down handling"
Next in thread: Bhaumik Bhatt: "[PATCH v3 11/12] bus: mhi: core: Mark and maintain device states early on after power down"
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Hi Bhaumik,

On 31 October 2020 1:04:07 AM IST, Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx> wrote:
>Hi Mani,
>
>On 2020-10-30 07:06, Manivannan Sadhasivam wrote:
>> On Thu, Oct 29, 2020 at 09:10:55PM -0700, Bhaumik Bhatt wrote:
>>> Currently, there exist a set of if...else statements in the
>>> mhi_pm_disable_transition() function which make handling system
>>> error and disable transitions differently complex. To make that
>>> cleaner and facilitate differences in behavior, separate these
>>> two transitions for MHI host.
>>>
>>
>> And this results in a lot of duplicated code :/
>>
>> Thanks,
>> Mani
>>
>
>I knew this was coming. Mainly, we can avoid adding confusing if...else
>statements that plague the current mhi_pm_disable_transition() function
>
>and in
>return for some duplicate code, we can make handling separate use cases
>
>easier
>as they could pop-up anytime in the future.
>

If that happens then do it but now, please no.

Thanks,
Mani

>>> Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
>>> ---
>>> drivers/bus/mhi/core/pm.c | 159
>>> +++++++++++++++++++++++++++++++++++++++-------
>>> 1 file changed, 137 insertions(+), 22 deletions(-)
>>>
>>> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
>>> index 1d04e401..347ae7d 100644
>>> --- a/drivers/bus/mhi/core/pm.c
>>> +++ b/drivers/bus/mhi/core/pm.c
>>> @@ -444,7 +444,7 @@ static int mhi_pm_mission_mode_transition(struct
>
>>> mhi_controller *mhi_cntrl)
>>> return ret;
>>> }
>>>
>>> -/* Handle SYS_ERR and Shutdown transitions */
>>> +/* Handle shutdown transitions */
>>> static void mhi_pm_disable_transition(struct mhi_controller
>>> *mhi_cntrl,
>>> enum mhi_pm_state transition_state)
>>> {
>>> @@ -460,10 +460,6 @@ static void mhi_pm_disable_transition(struct
>>> mhi_controller *mhi_cntrl,
>>> to_mhi_pm_state_str(mhi_cntrl->pm_state),
>>> to_mhi_pm_state_str(transition_state));
>>>
>>> - /* We must notify MHI control driver so it can clean up first */
>>> - if (transition_state == MHI_PM_SYS_ERR_PROCESS)
>>> - mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_SYS_ERROR);
>>> -
>>> mutex_lock(&mhi_cntrl->pm_mutex);
>>> write_lock_irq(&mhi_cntrl->pm_lock);
>>> prev_state = mhi_cntrl->pm_state;
>>> @@ -502,11 +498,8 @@ static void mhi_pm_disable_transition(struct
>>> mhi_controller *mhi_cntrl,
>>> MHICTRL_RESET_SHIFT,
>>> &in_reset) ||
>>> !in_reset, timeout);
>>> - if ((!ret || in_reset) && cur_state == MHI_PM_SYS_ERR_PROCESS) {
>>> + if (!ret || in_reset)
>>> dev_err(dev, "Device failed to exit MHI Reset state\n");
>>> - mutex_unlock(&mhi_cntrl->pm_mutex);
>>> - return;
>>> - }
>>>
>>> /*
>>> * Device will clear BHI_INTVEC as a part of RESET processing,
>>> @@ -566,19 +559,142 @@ static void mhi_pm_disable_transition(struct
>>> mhi_controller *mhi_cntrl,
>>> er_ctxt->wp = er_ctxt->rbase;
>>> }
>>>
>>> - if (cur_state == MHI_PM_SYS_ERR_PROCESS) {
>>> - mhi_ready_state_transition(mhi_cntrl);
>>> - } else {
>>> - /* Move to disable state */
>>> - write_lock_irq(&mhi_cntrl->pm_lock);
>>> - cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_DISABLE);
>>> - write_unlock_irq(&mhi_cntrl->pm_lock);
>>> - if (unlikely(cur_state != MHI_PM_DISABLE))
>>> - dev_err(dev, "Error moving from PM state: %s to: %s\n",
>>> - to_mhi_pm_state_str(cur_state),
>>> - to_mhi_pm_state_str(MHI_PM_DISABLE));
>>> + /* Move to disable state */
>>> + write_lock_irq(&mhi_cntrl->pm_lock);
>>> + cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_DISABLE);
>>> + write_unlock_irq(&mhi_cntrl->pm_lock);
>>> + if (unlikely(cur_state != MHI_PM_DISABLE))
>>> + dev_err(dev, "Error moving from PM state: %s to: %s\n",
>>> + to_mhi_pm_state_str(cur_state),
>>> + to_mhi_pm_state_str(MHI_PM_DISABLE));
>>> +
>>> + dev_dbg(dev, "Exiting with PM state: %s, MHI state: %s\n",
>>> + to_mhi_pm_state_str(mhi_cntrl->pm_state),
>>> + TO_MHI_STATE_STR(mhi_cntrl->dev_state));
>>> +
>>> + mutex_unlock(&mhi_cntrl->pm_mutex);
>>> +}
>>> +
>>> +/* Handle system error transitions */
>>> +static void mhi_pm_sys_error_transition(struct mhi_controller
>>> *mhi_cntrl)
>>> +{
>>> + enum mhi_pm_state cur_state, prev_state;
>>> + struct mhi_event *mhi_event;
>>> + struct mhi_cmd_ctxt *cmd_ctxt;
>>> + struct mhi_cmd *mhi_cmd;
>>> + struct mhi_event_ctxt *er_ctxt;
>>> + 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(MHI_PM_SYS_ERR_PROCESS));
>>> +
>>> + /* We must notify MHI control driver so it can clean up first */
>>> + mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_SYS_ERROR);
>>> +
>>> + 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,
>MHI_PM_SYS_ERR_PROCESS);
>>> + write_unlock_irq(&mhi_cntrl->pm_lock);
>>> +
>>> + if (cur_state != MHI_PM_SYS_ERR_PROCESS) {
>>> + dev_err(dev, "Failed to transition from PM state: %s to: %s\n",
>>> + to_mhi_pm_state_str(cur_state),
>>> + to_mhi_pm_state_str(MHI_PM_SYS_ERR_PROCESS));
>>> + goto exit_sys_error_transition;
>>> + }
>>> +
>>> + mhi_cntrl->ee = MHI_EE_DISABLE_TRANSITION;
>>> + mhi_cntrl->dev_state = MHI_STATE_RESET;
>>> +
>>> + /* Wake up threads waiting for state transition */
>>> + wake_up_all(&mhi_cntrl->state_event);
>>> +
>>> + /* Trigger MHI RESET so that the device will not access host
>memory
>>> */
>>> + if (MHI_REG_ACCESS_VALID(prev_state)) {
>>> + u32 in_reset = -1;
>>> + unsigned long timeout = msecs_to_jiffies(mhi_cntrl->timeout_ms);
>>> +
>>> + dev_dbg(dev, "Triggering MHI Reset in device\n");
>>> + mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
>>> +
>>> + /* Wait for the reset bit to be cleared by the device */
>>> + ret = wait_event_timeout(mhi_cntrl->state_event,
>>> + mhi_read_reg_field(mhi_cntrl,
>>> + mhi_cntrl->regs,
>>> + MHICTRL,
>>> + MHICTRL_RESET_MASK,
>>> + MHICTRL_RESET_SHIFT,
>>> + &in_reset) ||
>>> + !in_reset, timeout);
>>> + if (!ret || in_reset) {
>>> + dev_err(dev, "Device failed to exit MHI Reset state\n");
>>> + goto exit_sys_error_transition;
>>> + }
>>> +
>>> + /*
>>> + * Device will clear BHI_INTVEC as a part of RESET processing,
>>> + * hence re-program it
>>> + */
>>> + mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
>>> + }
>>> +
>>> + dev_dbg(dev,
>>> + "Waiting for all pending event ring processing to complete\n");
>>> + mhi_event = mhi_cntrl->mhi_event;
>>> + for (i = 0; i < mhi_cntrl->total_ev_rings; i++, mhi_event++) {
>>> + if (mhi_event->offload_ev)
>>> + continue;
>>> + tasklet_kill(&mhi_event->task);
>>> }
>>>
>>> + /* Release lock and wait for all pending threads to complete */
>>> + mutex_unlock(&mhi_cntrl->pm_mutex);
>>> + dev_dbg(dev, "Waiting for all pending threads to complete\n");
>>> + wake_up_all(&mhi_cntrl->state_event);
>>> +
>>> + dev_dbg(dev, "Reset all active channels and remove MHI
>devices\n");
>>> + device_for_each_child(mhi_cntrl->cntrl_dev, NULL,
>>> mhi_destroy_device);
>>> +
>>> + mutex_lock(&mhi_cntrl->pm_mutex);
>>> +
>>> + WARN_ON(atomic_read(&mhi_cntrl->dev_wake));
>>> + WARN_ON(atomic_read(&mhi_cntrl->pending_pkts));
>>> +
>>> + /* Reset the ev rings and cmd rings */
>>> + dev_dbg(dev, "Resetting EV CTXT and CMD CTXT\n");
>>> + mhi_cmd = mhi_cntrl->mhi_cmd;
>>> + cmd_ctxt = mhi_cntrl->mhi_ctxt->cmd_ctxt;
>>> + for (i = 0; i < NR_OF_CMD_RINGS; i++, mhi_cmd++, cmd_ctxt++) {
>>> + struct mhi_ring *ring = &mhi_cmd->ring;
>>> +
>>> + ring->rp = ring->base;
>>> + ring->wp = ring->base;
>>> + cmd_ctxt->rp = cmd_ctxt->rbase;
>>> + cmd_ctxt->wp = cmd_ctxt->rbase;
>>> + }
>>> +
>>> + mhi_event = mhi_cntrl->mhi_event;
>>> + er_ctxt = mhi_cntrl->mhi_ctxt->er_ctxt;
>>> + for (i = 0; i < mhi_cntrl->total_ev_rings; i++, er_ctxt++,
>>> + mhi_event++) {
>>> + struct mhi_ring *ring = &mhi_event->ring;
>>> +
>>> + /* Skip offload events */
>>> + if (mhi_event->offload_ev)
>>> + continue;
>>> +
>>> + ring->rp = ring->base;
>>> + ring->wp = ring->base;
>>> + er_ctxt->rp = er_ctxt->rbase;
>>> + er_ctxt->wp = er_ctxt->rbase;
>>> + }
>>> +
>>> + mhi_ready_state_transition(mhi_cntrl);
>>> +
>>> +exit_sys_error_transition:
>>> dev_dbg(dev, "Exiting with PM state: %s, MHI state: %s\n",
>>> to_mhi_pm_state_str(mhi_cntrl->pm_state),
>>> TO_MHI_STATE_STR(mhi_cntrl->dev_state));
>>> @@ -666,8 +782,7 @@ void mhi_pm_st_worker(struct work_struct *work)
>>> mhi_ready_state_transition(mhi_cntrl);
>>> break;
>>> case DEV_ST_TRANSITION_SYS_ERR:
>>> - mhi_pm_disable_transition
>>> - (mhi_cntrl, MHI_PM_SYS_ERR_PROCESS);
>>> + mhi_pm_sys_error_transition(mhi_cntrl);
>>> break;
>>> case DEV_ST_TRANSITION_DISABLE:
>>> mhi_pm_disable_transition
>>> --
>>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>>> Forum,
>>> a Linux Foundation Collaborative Project
>>>
>
>Thanks,
>Bhaumik

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

Next message: Hongyi Zhao: "Has the linux-kernel already implemented the functions in apollo-kernel?"
Previous message: John Hubbard: "Re: [PATCH v5 13/15] resource: Move devmem revoke code to resource framework"
In reply to: Bhaumik Bhatt: "Re: [PATCH v3 10/12] bus: mhi: core: Separate system error and power down handling"
Next in thread: Bhaumik Bhatt: "[PATCH v3 11/12] bus: mhi: core: Mark and maintain device states early on after power down"
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