Re: [PATCH v3 18/25] bus: mhi: ep: Add support for handling MHI_RESET

Alex Elder
2022-02-15T22:39:57Z

On 2/12/22 12:21 PM, Manivannan Sadhasivam wrote:
> Add support for handling MHI_RESET in MHI endpoint stack. MHI_RESET will
> be issued by the host during shutdown and during error scenario so that
> it can recover the endpoint device without restarting the whole device.
>
> MHI_RESET handling involves resetting the internal MHI registers, data
> structures, state machines, resetting all channels/rings and setting
> MHICTRL.RESET bit to 0. Additionally the device will also move to READY
> state if the reset was due to SYS_ERR.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

I might be getting tired out... But this looks good to me!

Reviewed-by: Alex Elder <elder@linaro.org>

> ---
> drivers/bus/mhi/ep/main.c | 53 +++++++++++++++++++++++++++++++++++++++
> include/linux/mhi_ep.h | 2 ++
> 2 files changed, 55 insertions(+)
>
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index 14cb08de4263..ddedd0fb19aa 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -471,6 +471,7 @@ static irqreturn_t mhi_ep_irq(int irq, void *data)
> struct device *dev = &mhi_cntrl->mhi_dev->dev;
> enum mhi_state state;
> u32 int_value;
> + bool mhi_reset;
>
> /* Acknowledge the interrupts */
> int_value = mhi_ep_mmio_read(mhi_cntrl, MHI_CTRL_INT_STATUS_A7);
> @@ -479,6 +480,14 @@ static irqreturn_t mhi_ep_irq(int irq, void *data)
> /* Check for ctrl interrupt */
> if (FIELD_GET(MHI_CTRL_INT_STATUS_A7_MSK, int_value)) {
> dev_dbg(dev, "Processing ctrl interrupt\n");
> + mhi_ep_mmio_get_mhi_state(mhi_cntrl, &state, &mhi_reset);
> + if (mhi_reset) {
> + dev_info(dev, "Host triggered MHI reset!\n");
> + disable_irq_nosync(mhi_cntrl->irq);
> + schedule_work(&mhi_cntrl->reset_work);
> + return IRQ_HANDLED;
> + }
> +
> mhi_ep_process_ctrl_interrupt(mhi_cntrl, state);
> }
>
> @@ -559,6 +568,49 @@ static void mhi_ep_abort_transfer(struct mhi_ep_cntrl *mhi_cntrl)
> mhi_cntrl->is_enabled = false;
> }
>
> +static void mhi_ep_reset_worker(struct work_struct *work)
> +{
> + struct mhi_ep_cntrl *mhi_cntrl = container_of(work, struct mhi_ep_cntrl, reset_work);
> + struct device *dev = &mhi_cntrl->mhi_dev->dev;
> + enum mhi_state cur_state;
> + int ret;
> +
> + mhi_ep_abort_transfer(mhi_cntrl);
> +
> + spin_lock_bh(&mhi_cntrl->state_lock);
> + /* Reset MMIO to signal host that the MHI_RESET is completed in endpoint */
> + mhi_ep_mmio_reset(mhi_cntrl);
> + cur_state = mhi_cntrl->mhi_state;
> + spin_unlock_bh(&mhi_cntrl->state_lock);
> +
> + /*
> + * Only proceed further if the reset is due to SYS_ERR. The host will
> + * issue reset during shutdown also and we don't need to do re-init in
> + * that case.
> + */
> + if (cur_state == MHI_STATE_SYS_ERR) {
> + mhi_ep_mmio_init(mhi_cntrl);
> +
> + /* Set AMSS EE before signaling ready state */
> + mhi_ep_mmio_set_env(mhi_cntrl, MHI_EP_AMSS_EE);
> +
> + /* All set, notify the host that we are ready */
> + ret = mhi_ep_set_ready_state(mhi_cntrl);
> + if (ret)
> + return;
> +
> + dev_dbg(dev, "READY state notification sent to the host\n");
> +
> + ret = mhi_ep_enable(mhi_cntrl);
> + if (ret) {
> + dev_err(dev, "Failed to enable MHI endpoint: %d\n", ret);
> + return;
> + }
> +
> + enable_irq(mhi_cntrl->irq);
> + }
> +}
> +
> int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
> {
> struct device *dev = &mhi_cntrl->mhi_dev->dev;
> @@ -827,6 +879,7 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
>
> INIT_WORK(&mhi_cntrl->ring_work, mhi_ep_ring_worker);
> INIT_WORK(&mhi_cntrl->state_work, mhi_ep_state_worker);
> + INIT_WORK(&mhi_cntrl->reset_work, mhi_ep_reset_worker);
>
> mhi_cntrl->ring_wq = alloc_workqueue("mhi_ep_ring_wq", 0, 0);
> if (!mhi_cntrl->ring_wq) {
> diff --git a/include/linux/mhi_ep.h b/include/linux/mhi_ep.h
> index 4f86e7986c93..276d29fef465 100644
> --- a/include/linux/mhi_ep.h
> +++ b/include/linux/mhi_ep.h
> @@ -75,6 +75,7 @@ struct mhi_ep_db_info {
> * @ring_wq: Dedicated workqueue for processing MHI rings
> * @state_work: State transition worker
> * @ring_work: Ring worker
> + * @reset_work: Worker for MHI Endpoint reset
> * @ch_db_list: List of queued channel doorbells
> * @st_transition_list: List of state transitions
> * @list_lock: Lock for protecting state transition and channel doorbell lists
> @@ -126,6 +127,7 @@ struct mhi_ep_cntrl {
> struct workqueue_struct *ring_wq;
> struct work_struct state_work;
> struct work_struct ring_work;
> + struct work_struct reset_work;
>
> struct list_head ch_db_list;
> struct list_head st_transition_list;