Re: [Patch v6 4/7] slimbus: Add support for 'clock-pause' feature

[Srinivas Kandagatla]

Thanks for the review comments



On 07/10/17 09:06, Jonathan NeuschÃfer wrote:
> Hi, some trivial comments below.
>
> On Fri, Oct 06, 2017 at 05:51:33PM +0200, srinivas.kandagatla@xxxxxxxxxx wrote:
> > From: Sagar Dharia <sdharia@xxxxxxxxxxxxxx>
> >
> > Per slimbus specification, a reconfiguration sequence known as
> > 'clock pause' needs to be broadcast over the bus while entering low-
> > power mode. Clock-pause is initiated by the controller driver.
> > To exit clock-pause, controller typically wakes up the framer device.
> > Since wakeup precedure is controller-specific, framework calls it via
> > controller's function pointer to invoke it.
> >
> > Signed-off-by: Sagar Dharia <sdharia@xxxxxxxxxxxxxx>
> > Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> > ---
> [...]
> > @@ -429,6 +444,14 @@ void slim_return_tx(struct slim_controller *ctrl, int err)
> >   		cur.cb(cur.ctx, err);
> >   
> >   	up(&ctrl->tx_sem);
> > +	if (!cur.clk_pause && (!cur.need_tid || err)) {
> > +		/**
>
> This isn't really a kerneldoc comment.
Will fix all such instances in next version.
> > +		 * remove runtime-pm vote if this was TX only, or
> > +		 * if there was error during this transaction
> > +		 */
> > +		pm_runtime_mark_last_busy(ctrl->dev.parent);
> > +		pm_runtime_put_autosuspend(ctrl->dev.parent);
> > +	}
> >   }
> >   EXPORT_SYMBOL_GPL(slim_return_tx);
> >   
> [...]
> > +/**
> > + * slim_ctrl_clk_pause: Called by slimbus controller to enter/exit 'clock pause'
> > + * Slimbus specification needs this sequence to turn-off clocks for the bus.
> > + * The sequence involves sending 3 broadcast messages (reconfiguration
> > + * sequence) to inform all devices on the bus.
> > + * To exit clock-pause, controller typically wakes up active framer device.
> > + * @ctrl: controller requesting bus to be paused or woken up
> > + * @wakeup: Wakeup this controller from clock pause.
> > + * @restart: Restart time value per spec used for clock pause. This value
> > + *	isn't used when controller is to be woken up.
> > + * This API executes clock pause reconfiguration sequence if wakeup is false.
> > + * If wakeup is true, controller's wakeup is called.
> > + * For entering clock-pause, -EBUSY is returned if a message txn in pending.
> > + */
> > +int slim_ctrl_clk_pause(struct slim_controller *ctrl, bool wakeup, u8 restart)
> > +{
> > +	int i, ret = 0;
> > +	unsigned long flags;
> > +	struct slim_sched *sched = &ctrl->sched;
> > +	struct slim_val_inf msg = {0, 0, NULL, NULL, NULL, NULL};
> > +
> > +	DEFINE_SLIM_BCAST_TXN(txn, SLIM_MSG_MC_BEGIN_RECONFIGURATION,
> > +				3, SLIM_LA_MANAGER, &msg);
> > +
> > +	if (wakeup == false && restart > SLIM_CLK_UNSPECIFIED)
> > +		return -EINVAL;
> > +
> > +	mutex_lock(&sched->m_reconf);
> > +	if (wakeup) {
> > +		if (sched->clk_state == SLIM_CLK_ACTIVE) {
> > +			mutex_unlock(&sched->m_reconf);
> > +			return 0;
> > +		}
> > +
> > +		/**
>
> ditto
>
> > +		 * Fine-tune calculation based on clock gear,
> > +		 * message-bandwidth after bandwidth management
> > +		 */
> > +		ret = wait_for_completion_timeout(&sched->pause_comp,
> > +				msecs_to_jiffies(100));
> > +		if (!ret) {
> > +			mutex_unlock(&sched->m_reconf);
> > +			pr_err("Previous clock pause did not finish");
> > +			return -ETIMEDOUT;
> > +		}
> > +		ret = 0;
> > +
> > +		/**
>
> ditto
>
> > +		 * Slimbus framework will call controller wakeup
> > +		 * Controller should make sure that it sets active framer
> > +		 * out of clock pause
> > +		 */
> > +		if (sched->clk_state == SLIM_CLK_PAUSED && ctrl->wakeup)
> > +			ret = ctrl->wakeup(ctrl);
> > +		if (!ret)
> > +			sched->clk_state = SLIM_CLK_ACTIVE;
> > +		mutex_unlock(&sched->m_reconf);
> > +
> > +		return ret;
> > +	}
> [...]
>
>
> Thanks,
> Jonathan NeuschÃfer