Re: [PATCH v3 24/25] bus: mhi: ep: Add support for suspending and resuming channels

Alex Elder
2022-02-15T22:40:48Z

On 2/12/22 12:21 PM, Manivannan Sadhasivam wrote:
> Add support for suspending and resuming the channels in MHI endpoint stack.
> The channels will be moved to the suspended state during M3 state
> transition and will be resumed during M0 transition.
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Looks good.

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

> ---
> drivers/bus/mhi/ep/internal.h | 2 ++
> drivers/bus/mhi/ep/main.c | 58 +++++++++++++++++++++++++++++++++++
> drivers/bus/mhi/ep/sm.c | 4 +++
> 3 files changed, 64 insertions(+)
>
> diff --git a/drivers/bus/mhi/ep/internal.h b/drivers/bus/mhi/ep/internal.h
> index 8654af7caf40..e23d2fd04282 100644
> --- a/drivers/bus/mhi/ep/internal.h
> +++ b/drivers/bus/mhi/ep/internal.h
> @@ -242,6 +242,8 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl);
> int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl);
> int mhi_ep_set_ready_state(struct mhi_ep_cntrl *mhi_cntrl);
> void mhi_ep_handle_syserr(struct mhi_ep_cntrl *mhi_cntrl);
> +void mhi_ep_resume_channels(struct mhi_ep_cntrl *mhi_cntrl);
> +void mhi_ep_suspend_channels(struct mhi_ep_cntrl *mhi_cntrl);
>
> /* MHI EP memory management functions */
> int mhi_ep_alloc_map(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr, size_t size,
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index e4186b012257..315409705b91 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -1106,6 +1106,64 @@ void mhi_ep_power_down(struct mhi_ep_cntrl *mhi_cntrl)
> }
> EXPORT_SYMBOL_GPL(mhi_ep_power_down);
>
> +void mhi_ep_suspend_channels(struct mhi_ep_cntrl *mhi_cntrl)
> +{
> + struct mhi_ep_chan *mhi_chan;
> + u32 tmp;
> + int i;
> +
> + for (i = 0; i < mhi_cntrl->max_chan; i++) {
> + mhi_chan = &mhi_cntrl->mhi_chan[i];
> +
> + if (!mhi_chan->mhi_dev)
> + continue;
> +
> + mutex_lock(&mhi_chan->lock);
> + /* Skip if the channel is not currently running */
> + tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[i].chcfg);
> + if (FIELD_GET(CHAN_CTX_CHSTATE_MASK, tmp) != MHI_CH_STATE_RUNNING) {
> + mutex_unlock(&mhi_chan->lock);
> + continue;
> + }
> +
> + dev_dbg(&mhi_chan->mhi_dev->dev, "Suspending channel\n");
> + /* Set channel state to SUSPENDED */
> + tmp &= ~CHAN_CTX_CHSTATE_MASK;
> + tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_SUSPENDED);

Somebody really needs to write a FIELD_UPDATE() macro to
do this read/modify/write pattern.

> + mhi_cntrl->ch_ctx_cache[i].chcfg = cpu_to_le32(tmp);
> + mutex_unlock(&mhi_chan->lock);
> + }
> +}
> +
> +void mhi_ep_resume_channels(struct mhi_ep_cntrl *mhi_cntrl)
> +{
> + struct mhi_ep_chan *mhi_chan;
> + u32 tmp;
> + int i;
> +
> + for (i = 0; i < mhi_cntrl->max_chan; i++) {
> + mhi_chan = &mhi_cntrl->mhi_chan[i];
> +
> + if (!mhi_chan->mhi_dev)
> + continue;
> +
> + mutex_lock(&mhi_chan->lock);
> + /* Skip if the channel is not currently suspended */
> + tmp = le32_to_cpu(mhi_cntrl->ch_ctx_cache[i].chcfg);
> + if (FIELD_GET(CHAN_CTX_CHSTATE_MASK, tmp) != MHI_CH_STATE_SUSPENDED) {
> + mutex_unlock(&mhi_chan->lock);
> + continue;
> + }
> +
> + dev_dbg(&mhi_chan->mhi_dev->dev, "Resuming channel\n");
> + /* Set channel state to RUNNING */
> + tmp &= ~CHAN_CTX_CHSTATE_MASK;
> + tmp |= FIELD_PREP(CHAN_CTX_CHSTATE_MASK, MHI_CH_STATE_RUNNING);
> + mhi_cntrl->ch_ctx_cache[i].chcfg = cpu_to_le32(tmp);
> + mutex_unlock(&mhi_chan->lock);
> + }
> +}
> +
> static void mhi_ep_release_device(struct device *dev)
> {
> struct mhi_ep_device *mhi_dev = to_mhi_ep_device(dev);
> diff --git a/drivers/bus/mhi/ep/sm.c b/drivers/bus/mhi/ep/sm.c
> index 9a75ecfe1adf..e24ba2d85e13 100644
> --- a/drivers/bus/mhi/ep/sm.c
> +++ b/drivers/bus/mhi/ep/sm.c
> @@ -88,8 +88,11 @@ int mhi_ep_set_m0_state(struct mhi_ep_cntrl *mhi_cntrl)
> enum mhi_state old_state;
> int ret;
>
> + /* If MHI is in M3, resume suspended channels */
> spin_lock_bh(&mhi_cntrl->state_lock);
> old_state = mhi_cntrl->mhi_state;
> + if (old_state == MHI_STATE_M3)
> + mhi_ep_resume_channels(mhi_cntrl);
>
> ret = mhi_ep_set_mhi_state(mhi_cntrl, MHI_STATE_M0);
> if (ret) {
> @@ -135,6 +138,7 @@ int mhi_ep_set_m3_state(struct mhi_ep_cntrl *mhi_cntrl)
> }
>
> spin_unlock_bh(&mhi_cntrl->state_lock);
> + mhi_ep_suspend_channels(mhi_cntrl);
>
> /* Signal host that the device moved to M3 */
> ret = mhi_ep_send_state_change_event(mhi_cntrl, MHI_STATE_M3);