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Message-ID: <a02c31409d696075b155ef2d6ee33009@codeaurora.org>
Date: Fri, 30 Oct 2020 12:34:07 -0700
From: Bhaumik Bhatt <bbhatt@...eaurora.org>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
jhugo@...eaurora.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 10/12] bus: mhi: core: Separate system error and power
down handling
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.
>> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
>> ---
>> 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
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum,
a Linux Foundation Collaborative Project
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