Re: [PATCH v3 17/25] bus: mhi: ep: Add support for powering down the MHI endpoint stack

Alex Elder
2022-02-15T22:39:51Z

On 2/12/22 12:21 PM, Manivannan Sadhasivam wrote:
> Add support for MHI endpoint power_down that includes stopping all
> available channels, destroying the channels, resetting the event and
> transfer rings and freeing the host cache.
>
> The stack will be powered down whenever the physical bus link goes down.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Not much to say here either, just a few suggestions.

-Alex

> ---
> drivers/bus/mhi/ep/main.c | 81 +++++++++++++++++++++++++++++++++++++++
> include/linux/mhi_ep.h | 6 +++
> 2 files changed, 87 insertions(+)
>
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index 016e819f640a..14cb08de4263 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -21,6 +21,8 @@
>
> static DEFINE_IDA(mhi_ep_cntrl_ida);
>
> +static int mhi_ep_destroy_device(struct device *dev, void *data);
> +
> static int mhi_ep_send_event(struct mhi_ep_cntrl *mhi_cntrl, u32 ring_idx,
> struct mhi_ep_ring_element *el)
> {
> @@ -492,6 +494,71 @@ static irqreturn_t mhi_ep_irq(int irq, void *data)
> return IRQ_HANDLED;
> }
>
> +static void mhi_ep_abort_transfer(struct mhi_ep_cntrl *mhi_cntrl)
> +{
> + struct mhi_ep_ring *ch_ring, *ev_ring;
> + struct mhi_result result = {};
> + struct mhi_ep_chan *mhi_chan;
> + int i;
> +
> + /* Stop all the channels */
> + for (i = 0; i < mhi_cntrl->max_chan; i++) {
mhi_chan = &mhi_cntrl->mhi_chan[i];
ch_ring = &mhi_chan->ring;

> + ch_ring = &mhi_cntrl->mhi_chan[i].ring;
> + if (!ch_ring->started)
> + continue;
> +
> + mhi_chan = &mhi_cntrl->mhi_chan[i];
> + mutex_lock(&mhi_chan->lock);
> + /* Send channel disconnect status to client drivers */
> + if (mhi_chan->xfer_cb) {
> + result.transaction_status = -ENOTCONN;
> + result.bytes_xferd = 0;
> + mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
> + }
> +
> + /* Set channel state to DISABLED */

Omit the above comment.

> + mhi_chan->state = MHI_CH_STATE_DISABLED;
> + mutex_unlock(&mhi_chan->lock);
> + }
> +
> + flush_workqueue(mhi_cntrl->ring_wq);
> + flush_workqueue(mhi_cntrl->state_wq);
> +
> + /* Destroy devices associated with all channels */
> + device_for_each_child(&mhi_cntrl->mhi_dev->dev, NULL, mhi_ep_destroy_device);
> +
> + /* Stop and reset the transfer rings */
> + for (i = 0; i < mhi_cntrl->max_chan; i++) {
mhi_chan = ...

if (!mhi_chan->ring.started)
continue;

> + ch_ring = &mhi_cntrl->mhi_chan[i].ring;
> + if (!ch_ring->started)
> + continue;
> +
> + mhi_chan = &mhi_cntrl->mhi_chan[i];
> + mutex_lock(&mhi_chan->lock);
> + mhi_ep_ring_reset(mhi_cntrl, ch_ring);
> + mutex_unlock(&mhi_chan->lock);
> + }
> +
> + /* Stop and reset the event rings */
> + for (i = 0; i < mhi_cntrl->event_rings; i++) {
> + ev_ring = &mhi_cntrl->mhi_event[i].ring;
> + if (!ev_ring->started)
> + continue;
> +
> + mutex_lock(&mhi_cntrl->event_lock);
> + mhi_ep_ring_reset(mhi_cntrl, ev_ring);
> + mutex_unlock(&mhi_cntrl->event_lock);
> + }
> +
> + /* Stop and reset the command ring */
> + mhi_ep_ring_reset(mhi_cntrl, &mhi_cntrl->mhi_cmd->ring);
> +
> + mhi_ep_free_host_cfg(mhi_cntrl);
> + mhi_ep_mmio_mask_interrupts(mhi_cntrl);
> +
> + mhi_cntrl->is_enabled = false;
> +}
> +
> int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
> {
> struct device *dev = &mhi_cntrl->mhi_dev->dev;
> @@ -548,6 +615,16 @@ int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
> }
> EXPORT_SYMBOL_GPL(mhi_ep_power_up);
>
> +void mhi_ep_power_down(struct mhi_ep_cntrl *mhi_cntrl)
> +{
> + if (mhi_cntrl->is_enabled)
> + mhi_ep_abort_transfer(mhi_cntrl);
> +
> + kfree(mhi_cntrl->mhi_event);
> + disable_irq(mhi_cntrl->irq);
> +}
> +EXPORT_SYMBOL_GPL(mhi_ep_power_down);
> +
> static void mhi_ep_release_device(struct device *dev)
> {
> struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
> @@ -828,6 +905,10 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
> }
> EXPORT_SYMBOL_GPL(mhi_ep_register_controller);
>
> +/*
> + * It is expected that the controller drivers will power down the MHI EP stack
> + * using "mhi_ep_power_down()" before calling this function to unregister themselves.
> + */
> void mhi_ep_unregister_controller(struct mhi_ep_cntrl *mhi_cntrl)
> {
> struct mhi_ep_device *mhi_dev = mhi_cntrl->mhi_dev;
> diff --git a/include/linux/mhi_ep.h b/include/linux/mhi_ep.h
> index 53895f1c68e1..4f86e7986c93 100644
> --- a/include/linux/mhi_ep.h
> +++ b/include/linux/mhi_ep.h
> @@ -260,4 +260,10 @@ void mhi_ep_unregister_controller(struct mhi_ep_cntrl *mhi_cntrl);
> */
> int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl);
>
> +/**
> + * mhi_ep_power_down - Power down the MHI endpoint stack
> + * @mhi_cntrl: MHI controller
> + */
> +void mhi_ep_power_down(struct mhi_ep_cntrl *mhi_cntrl);
> +
> #endif