Re: [PATCH v1 3/5] bus: mhi: core: Skip handling BHI irq if MHI reg access is not allowed

[Hemant Kumar]

Hi Mani,

On 5/11/20 11:53 PM, Manivannan Sadhasivam wrote:
> On Mon, May 11, 2020 at 07:03:07PM -0700, Hemant Kumar wrote:
> > Driver continues handling of BHI interrupt even if MHI register access
> > is not allowed. By doing so it calls the status call back and performs
> > early notification for the MHI client. This is not needed when MHI
> > register access is not allowed. Hence skip the handling in this case and
> > return. Also add debug log to print device state, local EE and device EE
> > when reg access is valid.
> >
> > Signed-off-by: Hemant Kumar <hemantk@xxxxxxxxxxxxxx>
> > Reviewed-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>
> > ---
> >   drivers/bus/mhi/core/main.c | 21 ++++++++++++++-------
> >   1 file changed, 14 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> > index 9ec9b36..467c0ba 100644
> > --- a/drivers/bus/mhi/core/main.c
> > +++ b/drivers/bus/mhi/core/main.c
> > @@ -369,22 +369,29 @@ irqreturn_t mhi_irq_handler(int irq_number, void *dev)
> >   	return IRQ_HANDLED;
> >   }
> >   
> > -irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *dev)
> > +irqreturn_t mhi_intvec_threaded_handler(int irq_number, void *priv)
> >   {
> > -	struct mhi_controller *mhi_cntrl = dev;
> > +	struct mhi_controller *mhi_cntrl = priv;
> > +	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> >   	enum mhi_state state = MHI_STATE_MAX;
> >   	enum mhi_pm_state pm_state = 0;
> >   	enum mhi_ee_type ee = 0;
> >   
> >   	write_lock_irq(&mhi_cntrl->pm_lock);
> > -	if (MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
> > -		state = mhi_get_mhi_state(mhi_cntrl);
> > -		ee = mhi_cntrl->ee;
> > -		mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
> > +	if (!MHI_REG_ACCESS_VALID(mhi_cntrl->pm_state)) {
> > +		write_unlock_irq(&mhi_cntrl->pm_lock);
>
> write_lock is only used for protecting 'mhi_cntrl->ee' but here we are not
> updating it if reg access is not valid. So there is no reason to hold this lock.
Original code is using write_lock to protect pm_state as well as 
mhi_cntrl->ee. This patch is keeping the lock same as original code. 
Just if condition logic is negated here due to that write_unlock_irq is 
added under if condition.
> > +		goto exit_intvec;
> >   	}
> >   
> > +	state = mhi_get_mhi_state(mhi_cntrl);
> > +	ee = mhi_cntrl->ee;
> > +	mhi_cntrl->ee = mhi_get_exec_env(mhi_cntrl);
>
> But it is needed here.
>
> Thanks,
> Mani
>
> > +	dev_dbg(dev, "local ee:%s device ee:%s dev_state:%s\n",
> > +		TO_MHI_EXEC_STR(mhi_cntrl->ee), TO_MHI_EXEC_STR(ee),
> > +		TO_MHI_STATE_STR(state));
> > +
> >   	if (state == MHI_STATE_SYS_ERR) {
> > -		dev_dbg(&mhi_cntrl->mhi_dev->dev, "System error detected\n");
> > +		dev_dbg(dev, "System error detected\n");
> >   		pm_state = mhi_tryset_pm_state(mhi_cntrl,
> >   					       MHI_PM_SYS_ERR_DETECT);
> >   	}
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> > a Linux Foundation Collaborative Project

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project