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Date: Mon, 16 Nov 2020 11:44:23 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Bhaumik Bhatt <bbhatt@...eaurora.org>
Cc: linux-arm-msm@...r.kernel.org, hemantk@...eaurora.org,
jhugo@...eaurora.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 10/12] bus: mhi: core: Separate system error and power
down handling
On Mon, Nov 09, 2020 at 12:47:29PM -0800, 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.
>
> Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Thanks,
Mani
> ---
> 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
>
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