Re: [PATCH v4 3/9] bus: mhi: core: Use helper API to trigger a non-blocking host resume

[bbhatt@xxxxxxxxxxxxxx]

On 2020-07-04 07:47, Manivannan Sadhasivam wrote:
> On Mon, Jun 29, 2020 at 09:39:36AM -0700, Bhaumik Bhatt wrote:
> > Autonomous low power mode support requires the MHI host to resume from
> > multiple places and post a wakeup source to exit system suspend. This
> > needs to be done in a non-blocking manner. Introduce a helper API to
> > trigger the host resume for data transfers and other non-blocking use
> > cases while supporting implementation of autonomous low power modes.
>
> Why can't you use pm_wakeup_event() as done in __mhi_device_get_sync()?
>
> Thanks,
> Mani

I forgot to address the __mhi_device_get_sync() function. Thanks for 
pointing out.

Is it preferable to always post wakeup source with hard boolean set?
We do want to wakeup from Suspend-to-Idle if system suspend happens to 
go that route.

As of now, we just by default do regular wakeup event and not hard.
I figured at some point we might need to distinguish between hard vs 
regular, hence the option but
it can be eliminated in favor of one or another.

Thanks,
Bhaumik

> > Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
> > ---
> >  drivers/bus/mhi/core/internal.h |  8 ++++++++
> >  drivers/bus/mhi/core/main.c     | 21 +++++++--------------
> >  drivers/bus/mhi/core/pm.c       |  6 ++----
> >  3 files changed, 17 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/bus/mhi/core/internal.h 
> > b/drivers/bus/mhi/core/internal.h
> > index bcfa7b6..cb32eaf 100644
> > --- a/drivers/bus/mhi/core/internal.h
> > +++ b/drivers/bus/mhi/core/internal.h
> > @@ -599,6 +599,14 @@ int mhi_queue_state_transition(struct 
> > mhi_controller *mhi_cntrl,
> >  int mhi_send_cmd(struct mhi_controller *mhi_cntrl, struct mhi_chan 
> > *mhi_chan,
> >  		 enum mhi_cmd_type cmd);
> >
> > +static inline void mhi_trigger_resume(struct mhi_controller 
> > *mhi_cntrl,
> > +				      bool hard_wakeup)
> > +{
> > +	pm_wakeup_dev_event(&mhi_cntrl->mhi_dev->dev, 0, hard_wakeup);
> > +	mhi_cntrl->runtime_get(mhi_cntrl);
> > +	mhi_cntrl->runtime_put(mhi_cntrl);
> > +}
> > +
> >  /* Register access methods */
> >  void mhi_db_brstmode(struct mhi_controller *mhi_cntrl, struct db_cfg 
> > *db_cfg,
> >  		     void __iomem *db_addr, dma_addr_t db_val);
> > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> > index 1f622ce..8d6ec34 100644
> > --- a/drivers/bus/mhi/core/main.c
> > +++ b/drivers/bus/mhi/core/main.c
> > @@ -909,8 +909,7 @@ void mhi_ctrl_ev_task(unsigned long data)
> >  		 * process it since we are probably in a suspended state,
> >  		 * so trigger a resume.
> >  		 */
> > -		mhi_cntrl->runtime_get(mhi_cntrl);
> > -		mhi_cntrl->runtime_put(mhi_cntrl);
> > +		mhi_trigger_resume(mhi_cntrl, false);
> >
> >  		return;
> >  	}
> > @@ -971,10 +970,8 @@ int mhi_queue_skb(struct mhi_device *mhi_dev, 
> > enum dma_data_direction dir,
> >  	}
> >
> >  	/* we're in M3 or transitioning to M3 */
> > -	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state)) {
> > -		mhi_cntrl->runtime_get(mhi_cntrl);
> > -		mhi_cntrl->runtime_put(mhi_cntrl);
> > -	}
> > +	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state))
> > +		mhi_trigger_resume(mhi_cntrl, false);
> >
> >  	/* Toggle wake to exit out of M2 */
> >  	mhi_cntrl->wake_toggle(mhi_cntrl);
> > @@ -1032,10 +1029,8 @@ int mhi_queue_dma(struct mhi_device *mhi_dev, 
> > enum dma_data_direction dir,
> >  	}
> >
> >  	/* we're in M3 or transitioning to M3 */
> > -	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state)) {
> > -		mhi_cntrl->runtime_get(mhi_cntrl);
> > -		mhi_cntrl->runtime_put(mhi_cntrl);
> > -	}
> > +	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state))
> > +		mhi_trigger_resume(mhi_cntrl, false);
> >
> >  	/* Toggle wake to exit out of M2 */
> >  	mhi_cntrl->wake_toggle(mhi_cntrl);
> > @@ -1147,10 +1142,8 @@ int mhi_queue_buf(struct mhi_device *mhi_dev, 
> > enum dma_data_direction dir,
> >  	read_lock_irqsave(&mhi_cntrl->pm_lock, flags);
> >
> >  	/* we're in M3 or transitioning to M3 */
> > -	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state)) {
> > -		mhi_cntrl->runtime_get(mhi_cntrl);
> > -		mhi_cntrl->runtime_put(mhi_cntrl);
> > -	}
> > +	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state))
> > +		mhi_trigger_resume(mhi_cntrl, false);
> >
> >  	/* Toggle wake to exit out of M2 */
> >  	mhi_cntrl->wake_toggle(mhi_cntrl);
> > diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> > index 661d704..5e3994e 100644
> > --- a/drivers/bus/mhi/core/pm.c
> > +++ b/drivers/bus/mhi/core/pm.c
> > @@ -1139,10 +1139,8 @@ void mhi_device_put(struct mhi_device *mhi_dev)
> >
> >  	mhi_dev->dev_wake--;
> >  	read_lock_bh(&mhi_cntrl->pm_lock);
> > -	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state)) {
> > -		mhi_cntrl->runtime_get(mhi_cntrl);
> > -		mhi_cntrl->runtime_put(mhi_cntrl);
> > -	}
> > +	if (MHI_PM_IN_SUSPEND_STATE(mhi_cntrl->pm_state))
> > +		mhi_trigger_resume(mhi_cntrl, false);
> >
> >  	mhi_cntrl->wake_put(mhi_cntrl, false);
> >  	read_unlock_bh(&mhi_cntrl->pm_lock);
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
> > Forum,
> > a Linux Foundation Collaborative Project